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Technical MOTOR..Why Stromberg 97s over 94's?

Discussion in 'The Hokey Ass Message Board' started by 4t64rd, Nov 17, 2003.

  1. I know next to nothing about flatheads, Just started reading some books. Why are Stromberg 97s used more often than 81s, 48s, or Holley/Ford 94s (or, why are that that much more expensive.). Is there some advantage in tuning or adjusting them that the 94s do not have? Are there any advantages to 97s over 94s in a dual carb setup for the street? 94s have a slightly higher CFM rating than 97s, does that small amount really make that big of a difference? I really hate to spend extra money for a nominal performance difference.
     
  2. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,681

    Bruce Lancaster
    Member Emeritus

    The 94 is a much more modern carb with better control of mixture in several different areas.
    Two things in favor of Stromberg: When used unaltered, that is straight from OEM use with no metering changes, it is more likely to run well on a multi-carb setup than the 94, which needs to have its power valve changed for lower vac actuation in most applications. Second, most serious racers in the early days ran alcohol or hot fuels--in many cases even street cars had a second manifold and fuel tank and ran fuel at the strip or lakes and then swapped on the gas carbs to go home. Strombergs are probably the easiest carbs on the planet to alter for high fuelflow rates, and so were universally used on carbed competition cars. Instant image--Stromberg=racer.
    Early street use hot rods after WWII used both quite frequently--I would guess 94's weren't used much prewar because they hadn't yet reached junkyards and Pep Boys yet.
     
    my2nd40 likes this.
  3. 1. What do you have to do to one to adapt the power valve to run with less vaccuum? would the 94 still be useable in a 2 carb setup with the power valves fixed.
     
  4. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,681

    Bruce Lancaster
    Member Emeritus

    Manifold vac drops very quickly when throttle opens on a multi carb setup because so much breathing area is available. The vac actuated power valve thinks the engine is pulling hard before it really is and enriches the mix before it's needed, resulting in low power and smoke. The cure is a valve that opens at a lower than stock vac level, readily available in the aftermarket.
    I haven't looked, but I would bet the Holley carb tech site has a good section on this--late H four barrels use the same design power valve.
     

  5. modernbeat
    Joined: Jul 2, 2001
    Posts: 1,296

    modernbeat
    Member
    from Dallas, TX

    Because 97's are simple - like our little brains!

    Actually, 286Merc wrote a very very good method on setting up 94 Carbs for a multi-carb setup. If he doesn't stick it up here, I'll find it tonight and post it.
     
  6. Bugman
    Joined: Nov 17, 2001
    Posts: 3,483

    Bugman
    Member

    Power valves are easily interchangable. Any good parts store should have a nice assortment. You don't actually alter the vlave, it's preset. You just replace it with a different one with a different preset. The number is stamped on the side, and reads in inches of vacum(like a 6.5, or 4.5) They're $6-$10 each depending on where you get them. Jegs and Summit(blasphemers) sell them too if your local parts house doesn't.

    I'd go with 94's cause their so much cheaper, and easier to get parts for.

    -Bugman Jeff
     
  7. zibo
    Joined: Mar 17, 2002
    Posts: 2,361

    zibo
    Member
    from dago ca

    the 94's are so easy to figure out,
    especially when on the side of the road,
    there are no special tools needed,
    and internal parts are over the counter.

    If you are worried about authenticity or whatever,
    and you have $$
    than you can't beat the 97's for sure.

    tp
     
  8. 286merc
    Joined: Mar 3, 2001
    Posts: 1,793

    286merc
    Member
    from Pelham, NH

    I resent that remark Jason, I fried my brains years ago before I ran into this crowd [​IMG]

    Here is that tuning thingie I did a few years ago, hope it helps.

    <center><h3>The KEY to using 94s by 286Merc</h3></center>


    Lots of confusion still remains about using Holley 94's and vacuum only distributors on 8BA's and early Y blocks.
    I'll just talk about the 1948-54 8BA style distributor.
    Over 2 years ago I got into a discussion with an expert on another forum who positively stated that you could not run dual 94's and a stock distributor. When I said I better take my setup apart then all hell broke loose. A few others keep referring to an outdated 1954 magazine article like it was some type of gospel.

    First of all there are over 17 varieties of the 94 style family, starting back in 1938 with the Chandler Grove and ending with the 1957 272 Y block for Ford production. Generic parts store replacements were available well into the 70's as the Holley 2100 and 2110. The Y block versions differ from the true 94 (which is the .094" venturi diameter) since they have a 1.0" and 1.062" venturi and often have a 1 or 1 1/16 marking on the side. There was even a 1 1/8" aftermarket version available that was quite common on hopped up VW's. The Lincoln V12 had a LZ casting which was also a 1" venturi. Bendix and Stromberg even got into the act, a Stromberg 94 clone actually has 97 on the side and is often found on EBay selling as a true 97!

    The CFM of the 94 family varies from 150 to 190 for ones used on Ford vehicles. The larger venturies will give a slight power increase in even a stock or mildly modified engine.

    Before attempting a tear down get a copy of the Ford procedure and a detailed parts blow up. It is part of the Shop Manual but some arent as detailed. The 1952 car manual or the aftermarket 1952-54 combined version is the best IMO.

    I always suggest that users start with a matched pair of casting models that have the vacuum port on the lower right side of the bowl; you can not use the earlier versions without a vacuum port with the stock 8BA distributor. These carbs carry bowl ID's of 7RT, 8BA, 8RT, EAA, EAB, EBU, EBV, ECG, 2100, 2110 and probably some I missed. If you decide to use any of the Y block carbs then remove and plug the spark control valve in the base.

    Another thing to check for is the nozzle bar, there were standard and hi-lift nozzle bars; dont mix types. The Shop Manuals suggested show the differences quite clearly. The drill bits specified for cleaning passages can be found at hobby/model shops. Guitar strings are good alternatives should they be handy.
    After a thorough cleaning, check for any cracks, warpage or corrosion, repair or discard the bad piece. One old tried and true method of truing up the bowl and air horn surfaces is to place a clean sheet of 220 grit wet/dry paper on a pane of glass and gently slide the part over it; visually look for low spots. Finish off with 400 grit for a nice smooth surface. It is always good to have several parts carbs. Next step is to rebuild them exactly the same. Dont be suprised by what you will find inside of that flea market goodie, parts were often swapped without consideration of correctness even in carb shops. Just do both the same and to original specs.
    Spend a little extra time polishing up any interior mold roughness; a Dremel works great for this.

    Next is the throttle shaft. For dual carbs using drivers side linkage you need extended throttle rods. These can be found on many early and later carbs that used a hand throttle. Quite common on 1948 and later trucks as well.
    Ford says .008" wear is OK but that usually also means the base casting is egg shaped by now and leaking vacuum like a sieve. The first step cure is an oversize shaft and a reamed base; try for a .002" fit. In extreme cases you will have to bore out the base and fit a bushing that should be a bit undersize and reamed to fit; getting everything realigned can get tricky. Several Internet and Hemmings advertisers can supply the needed parts or even rebuilt bases.

    Then pay particular attention to fitting the butterflies to the throttle bores. That fit is VERY important and you might need to have several extra carbs (of any ID) on hand to find the tightest fit. The Y block plates are slightly larger than the flathead versions so dont get them mixed up. I like repeating myself about spare carbs.
    Hold up to a light to check, there should be the tiniest sliver of light visible. Also be certain the bases arent severely pitted and butterflies corroded on the edges, a sure source of vacuum problems. ALSO be sure you dont reassemble the plates backwards!

    Leave the choke plate in place for both carbs. Altho only one will be choked the plate is required for good air flow direction. Tests have shown a hp loss without the plate.

    Next comes the true test, tuning them up.
    I like to start with only one carb mounted with a known good air filter; not some restrictive import. Securely block off the other hole. Temporarily block off the vacuum line. Start the engine and adjust the carb for a good idle, be sure there are no vacuum leaks on this carb and over at the block off plate and at the manifold ports. Dishwashing liquid and water mix in a spray bottle works great. A leak sucking vacuum will cause a stumble, an air leak will cause bubbles. Do not ever use WD-40 or other flamable liquid. Warm up the engine and secure the choke wide open.

    Now hook up a vacuum gauge to the carb port; dont even think about running duals (or trips) without one. Assuming the engine is tight, there should be around 18"/hg at idle. If it's much lower then it's time to trouble shoot. I'm assuming a non full race competition cam. Rev it up a bit, the vacuum should hold fairly steady thru at least 2500 rpm.
    Note that Im leaving the distributor vacuum off for now and not worrying about the advance. If you are absolutely/positively sure the distributor is perfect then hook it up if it makes you happy. I personally prefer as few possible problem areas at this stage. Tweak the idle mixture screws for maximum vacuum and a smooth idle, actual rpm is not important but it is a lot quiter down around 5-600 rpm.

    If everything is OK then swap carbs and repeat. Its a lot easier to get the idle set this way than with both in place plus you can find problems easier. And not place the blame on something else later on. If you havent installed the new intake yet then by all means do the initial adjustments on the stock one.

    Now mount both carbs but no linkage. Get out the Uni-Syn that you should have bought along with the vacuum gauge. Use the Uni-Syn to measure/equalize air flow of both carbs AND the vacuum gauge to set final idle mixture. Final result should coincide with maximum vacuum. There are other balancing devices available, if you are familiar with their operation then use them.
    Then hook up the linkage and do it all over again. This step assures that the linkage is not applying any control to the throttle rods. Tighten down the stops.
    Be sure you pay attention to blocking off the not in use vacuum port. Only the front carb will be needed to provide a vacuum signal to the distributor.
    By this time you should have 2 almost identical carbs.

    Use clean, fresh and well filtered gas. If using an electric pump set the pressure regulator for 2.5 lbs maximum.

    Hook up the choke cable to one carb, usually the rear. Hook up the vacuum line from the front carb to the distributor. Hook up the vacuum gauge to the rear carb; the original readings should be pretty close. If not check for hose or diaphram leaks.

    Now its time for Truth or Consequences.
    Extend the vacuum gauge hose into the vehicle. I prefer to have someone else do the reading while I pay attention to the driving. Record the readings throughout a full driving pattern, from idle to wide open throttle as you go thru the gears.
    How does the response feel? Any pinging? Stumble or excessive loading/bogging down?

    The ideal is to have the power valves open only when they are needed to enrich the mixture. This will be at or near full throttle or under a stiff load like going up a hill. Many of you may not ever want to wind things up that hard. The previous was intended more for stockers who are usually not going much beyond 2500 rpm. For rodders use the 2500 figure as a good place to start opening the valves.

    If you are staying above 7-8" thru all phases of your way of driving then chances are you are good to go. Stock Ford power valves are 7.5's which means that at that vacuum they open. Tolerance is roughly 1 point either way.
    If not then it will be necessary to go to a numerically lower power valve. This may raise a few eyebrows but try only one at first; the staggering effect may be to your liking. The front 2 cylinders are often starved with stock and some aftermarket intakes. Fuel flow is a hit and miss operation with all but the best designs.
    In most cases a pair of 4.5's will handle all but the hairiest cam street engines. I run 4.5's on my 286 and 5.5's for many customer built 276's with Schneider .395" cams.
    Go to the Holley Technical web site; power valves havent changed nor have the jets for almost 65 years; any speed shop can get what you need. Lots of good info on the Holley site. The new Holley "Hi Performance" PV's will work but require a bit of filing to clear.

    The worse thing you can do is to plug or otherwise defeat the power valves in this configuration. Running 6 or 8 carbs on a hemi is something altogether different.

    Once you're sure that the valves arent dumping too early then put in a fresh set of plugs and take a half hour ride at highway speeds. Read the plugs and change jet sizes ONLY if absolutely necessary. One size either way should be enough. Stock jets at sea level are .051; .049 and.047 were used at altitudes in the 5000-15000 foot range.
    Sometimes changing to a different heat range or brand of plug is a better move. NKG BL6 plugs give me the best results and consistentcy. This is all called fine tuning.

    So yes, dual 94's and a stock vacuum distributor are compatible a good many times. Dont expect to go racing or expect reliable fire beyond 4000 rpm; this is still a compromise since the distributor is not receiving the vacuum signal it was designed for. If you want a bit more advance (or reduced lack of as the distributor runs backwards from the typical vacuum operation) then turn the spring pins on the top of the plate with pliers. They are an eccentric and the spring tension is adjustable.
    There are numerous conversions and aftermarket ignition options available; it just takes time and money.

    The above was a compilation of over 45 years of using these carbs on flatheads and overheads, plus several articles in HRM and others going back as long, and finally some of the more recent books.
    I would recommend Tex Smiths Flathead manual as good reading altho it is not without errors and omissions.
    This article will also be useful in some areas when using 3 carbs, however there are differences involved. Thats another article for down the road.



    Ive made a few minor edits to the original article as it was strictly 8BA specific and aimed more to the semi restorer/non rodder type. There is no reason you cant use 94's on the earlier flatheads either, the requirement for matching still holds but you can use any variety. Simply plug the venturi vacuum port and the spark control valve on Y block types should be removed and plugged.
     
  9. delaware george
    Joined: Dec 5, 2002
    Posts: 1,246

    delaware george
    Member
    from camden, de

    this should deffinetly be in the tech files
     
  10. Thanks 286. I'll be using this info soon as I'm getting my '51 Merc w/ two 94's ready to go.
     
  11. hankcash
    Joined: Apr 18, 2002
    Posts: 2,653

    hankcash
    Member

    Excellent info 286.
    I am a 94 fan myself.
    I have rebuilt many of them on the road and you can't beat the reliability and ease of repair.
    I have a question...
    I have several parts 94's that I am rebuilding and some of them have a hole (looks to be done aftermarket) drilled in the bowl cover section that houses the pump spring and plunger. Why do some of my 94's have this hole and some not?
    I don't think that this was covered in the previous post, but I do speed read and sometimes miss information while reading...
    thanks-
    HC
     

    Attached Files:

  12. hankcash
    Joined: Apr 18, 2002
    Posts: 2,653

    hankcash
    Member

  13. Petejoe
    Joined: Nov 27, 2002
    Posts: 12,264

    Petejoe
    Member
    from Zoar, Ohio

    Thanks Carl! This gives me enough to get started on. I have always shyed away from rebuilding carbs but your step by step will allow me to learn them. Great post! Definitely tech material.
     
  14. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,681

    Bruce Lancaster
    Member Emeritus

    On that drilled hole, there is a lot of variety in the venting of 94's. Apparently there were issues of some sort in venting that area on very early carbs, as the bulletins call for a notch to be cut in early carbs lacking one from the factory inside the topcasting between the float area and this pocket over the accel pump.
    Some 94's have an internal vent pipe into the throat, some have the tiny oval indent on the front of the airhorn cut out, and some have that hole behind the upper pump linkage. It's difficult to say what happened when, especially on the pre-49 carbs, because most have been commercially rebuilt and are made of mixed parts from 78-99-21 and 59 carbs. At any rate, venting is about the only area in the early carbs that was changed or modified much along the way. My earliest paper on those carbs seems to show a hole in the pump dome on the side rather than the back, but this isn't present on any of the real Chandler Groves I've got.
     
  15. 286merc
    Joined: Mar 3, 2001
    Posts: 1,793

    286merc
    Member
    from Pelham, NH

    Hank, Ive never seen a hole like that in a 94 before, that looks like it was done with a hand drill.

    Following up on Bruces comments I wonder if it was a regional thing to possibly cure vapor lock or similar; it does get a bit warmer down your way at times.
    The picture shadow almost has me seeing another very tiny hole that is drilled into the carb?? If so it would put it right above the accelerator pump lever in that air pocket (for want of a better term) that I believe Bruce is referring to.
     
  16. hankcash
    Joined: Apr 18, 2002
    Posts: 2,653

    hankcash
    Member

    286-
    I have four 94's and two of em' have the hole and the other two don't. I have also seen other 94's in the area on other cars and for sale at swaps and some of them have the hole as well.... It was for sure done with a hand drill as you can see where the bit cut into the left section of the casting...
    I have run one with the hole and I have run one without.
    They both work fine, but I do have to set the mixture screws differently between the ones with holes and the ones without (maybe just a coincedence)...
    It must have something to do with vapor lock or vaccum pressure in the pump lever chamber or something.....
    interesting....
    HC
     
  17. kritz
    Joined: Aug 6, 2003
    Posts: 553

    kritz
    Member
    from flint, mi

    i'm glad someone asked (and had a pic to post)regarding the holes....flatheadpete and i were just trying to figger out what the heck the difference is....i've been trying to get a matching set of 94's together (because i can't afford 97's) and i've come across alot with the drilled holes...i even have a couple of strange ones...one has 2 holes drilled through the plunger housing in addition to the vent pipe, and one with one hole through the housing with no vent pipe...pete just had the hole in his welded shut and reported that it ran much better being plugged...
     
  18. fatassbuick
    Joined: Jul 6, 2001
    Posts: 989

    fatassbuick
    Member

  19. 286merc
    Joined: Mar 3, 2001
    Posts: 1,793

    286merc
    Member
    from Pelham, NH

    Michigan too? This should give Bruce something to do; research early auto shop and circle track oriented magazines for the source of that hole.

    This mystery needs an answer but meanwhile JB to the rescue!
     
  20. Iceberg
    Joined: Jan 5, 2003
    Posts: 424

    Iceberg
    Member

    I used Holly 94's because I had them and parts were easy to get. I could not get my set lean enough and just about gave up and went to a 4bbl manifold. I tried getting advised on the setup and quickly found out that no two old timers agreed on how to set them up. The main point of difference seems to be on weather to keep the power valves or not. I had a Portland area and Northern California racecar mechanic; Jamie Fox set mine up. He was Wayne Harry's crew chief in the 60's &amp; 70's and has worked with a lot of famous flathead race cars. He fixed me up quickly by plugging the power valves (like his friend Flathead Jack recommends)&amp; drilling his own main jets. My truck now runs great now and purrs @ idle (500 rpm). I tried 6.5 &amp; 4.5 power valves and jets from .50 to .045. It just plain kicked my ass! I did switch to a quality driver's side linkage on extended throttle shafts after trying the cheap passenger side Offy adjustable linkage. Most 94's have some wear on the throttle balls so the adjustable linkage will drag a cause sticking problems. Once you get your 94's set up they are great and cost about what a single core 97 would run you.


     
  21. Thanks everyone, I have 2 coming from a guy on FordBarn.com and 1 I got off egay, plus the one that is on the TX Flathead (it's still looking for a ride South from Shreveport if my friend Larry ever gets back and in touch with FuelF/C). Hopefully they can be mixed and matched to create 2 or 3 good ones.

    once I get them rebuilt, my codger friend here says he can make multiples run as easily as 1. Something (like was said) about power valves and progressive linkage he knows how to make.
     
  22. Mr 42
    Joined: Mar 27, 2003
    Posts: 1,215

    Mr 42
    Member
    from Sweden

    I guess i could be one of those gospel guys that 286´merc refers to. I dont understand how an article that was true in 1954 could be outdated? Im not aware of any changes of the 8BA distributor function since 1954?

    If you readjust the dizzy for the dualcarb venturi vacuum levels it will work, but its a lot of work. Anyway i thinki its important to understand why using manifold vacuum on a 8Ba dizzy dont work.

    Anyway here is the outdated article read and make your own decision

    #########################
    Motor Life Feb 1954


    Spark Advance Hop-up Trouble Spot By Barney Navarro

    Among the mistakes made in hopping up engines, few exceed in number the misapplication of spark advancing principles. The chief source of error is the limited information available on the subject of spark lead. That which is distributed, unfortunately, fails to cover some essential factors and very often is no more than a comment to the effect that fuel charges take a certain amount of time to burn so spark must be advanced enough to compensate for the time lapse.

    Well informed engineers wish that the problem really was that simple. Most ignition system purchasers overlook every factor except the amount of spark produced. The wrong system can cause plenty of trouble: plug fouling, poor gas mileage (even though the engine has no tendency to misfire), overheating in slow traffic, and other maladies. Basically, engines require some means of advancing spark timing as rpm increases since the pistons, in effect, try to get ahead of the burning speed of fuel charges. Combustion, witch takes a definite length of time, must occur when pistons are at the top dead center before the start of the downward power stroke. If burning finishes too early, energy is wasted because the resultant pressure rise produces a force opposition to rotation. This is readily apparent when starting an engine that has too much spark lead; it will actually kick back against the starter’s efforts. Modern high compression engines, while under full load, audibly indicate spark that is too far advanced by pinging. So the popular method of setting spark timing for maximum horsepower is to set it just below the ping point under full throttle operation. Distributors that employ flyweight governor advance mechanisms use a spark advance curve that conforms to the engine’s requirements under full throttle at any point within the rpm range. At low rpm a lesser spark lead is required so the governor advances a small amount. As speed picks up it advances more and more, always conforming to the full throttle full load requirements. On a drag machine, where full throttle and full load conditions are maintained, the flyweight governor is required. But for ordinary driving, which consists mainly of partial throttle operations with Very light loads, it is not enough. Some other means of compensating for varying loads must be provided. The load compensator is necessary because a light fuel mixture burns more slowly than a heavy charge since the concentration is less and flame takes longer to travel from one fuel particle to the other. If the utmost energy is to be obtained from light charges, their burning should be completed at the same point that the heavy charges finish. So if they take longer, the only way to make them finish at the same point is to start them earlier. Consequently, partial throttle partial load operation requires more spark lead at any given speed than is required at full throttle full load. Load compensation is the most commonly achieved by using intake manifold vacuum to actuate a diaphragm. This diaphragm advances and retards the distributor breaker plate and in some cases the whole distributor case. When the engine is operated with Very light throttle pressure, the manifold vacuum is high, so the diaphragm advances the spark timing to produce the most efficient combustion possible. As the throttle is depressed, the vacuum drops of and the diaphragm produces less advance until it reaches a point of being completely ineffective at wide open throttle. Thus the ideal load compensation is always maintained and results in more power from every drop of fuel.

    The second most popular method of obtaining load compensation, though further from perfection is that employed in Ford V-8 distributors from 1932 trough 1948. Instead of a diaphragm, there is piston brake actuated by manifold vacuum, The flyweight governor mechanism is equipped with a breaking disk which cancels five degrees of the governor’s advance when pressure is brought to bear on its edge. At this edge a spring-loaded piston is located in a small cylinder. The spring is on the side of the piston opposite the disc so it causes the piston to be pushed against the disc. Vacuum is introduced on the spring side to oppose its action and lift the piston off the disc. In action, the high vacuum produced by operation with small throttle openings lifts the piston of the disk, allows the full action of governor weights to take effect and gives the Ford engine five degrees more spark advance. By depressing the throttle further, the manifold vacuum drops off and the spring again pushes the piston against the disc to retard the spark. The flaw in the operation of this mechanism lies in the fact that it is either “full on or full off” and permits no gradual compensation like the diaphragm.

    Ford’s latest method of controlling spark advance employees an ingenious system utilizing manifold vacuum and venturi vacuum. With this system the flyweight governor is eliminated and in its place is nothing but a diaphragm. This diaphragm not only advances the spark to conform to rpm changes but is also makes load compensation adjustments. All ´49 through´54 Ford and Mercury carburetors have in addition to the conventional manifold vacuum takeoff, such as is found in the throttle body of most passenger car carburetors, a connecting venturi vacuum passage. The manifold vacuum, as usual, is obtained from a small port in the throttle body located slightly above the butterfly’s closed, position, on the side where the butterfly swings upward to open. When the throttle is closed at idling, the vacuum port does not receive vacuum because it is on the opposite side of the butterfly. As the throttle is opened slightly, this port is uncovered and a vacuum is applied to the distributor diaphragm to advance the spark. If the throttle is fully depressed, the manifold vacuum is destroyed and no advance takes place. As speed increases, however, the venturi vacuum increases gradually and advances the spark to conform to the rpm. Letting up on the throttle increases the manifold vacuum (Provided it isn’t let up all the way) and the spark receives load compensation. A balance is always maintained so that the correct amount of spark advance is supplied for all speed and load conditions.

    The greatest installation errors center around the misunderstanding of the late Ford distributors. A distressingly large number of mechanics are unaware of the difference between manifold vacuum and venturi vacuum. In fact many attempt to operate Ford and Mercury distributors by connecting the vacuum line to the windshield wiper connection on dual intake manifolds. This sometimes results from a desire to use the old Stromberg carburetors, which are not equipped with vacuum takeoff. So the simple solution seems to connecting the distributor vacuum line to the handiest apparent source of vacuum. Such practice is worse than having no spark control at all for when the engines idles the spark advances fully and retards as throttle is depressed. There is no venturi vacuum available to advance the spark as the speed picks up and it remains retarded until the throttle is let up. So if the old style carburetors are preferred, the stock Ford distributors must be discarded on the late models. However, Stromberg has resumed production of the old “97” and is now fitting it with a venturi vacuum takeoff to make its use feasible.

    Four throat carburetion installations also have had their share of improper distributors. Early articles in certain publications gave the impression that no vacuum control whatsoever could be tolerated. It wasn’t pointed out that the only forbidden type is that of the stock `49 through `54 Ford and Mercury distributor. This caused many to purchase distributors and magnetos that were equipped with flyweight governors only. Such installations get very poor gas mileage, so the car owners blame the four-throat carburetor. Even more irritating, is the tendency for spark plugs to foul. Having no load compensation, the spark is never far enough advanced under partial throttle to fire the fuel mixture charges at the most opportune time. In effect, the engine is being operated with a lower effective compression ratio because burning is completed as the pistons travel down the cylinder bores. And since the plugs never receive a hot flame, soot collects on them. Furthermore, the condition cannot be remedied by using hotter plugs because they will burn up under full throttle operation of flyweight governor distributor with vacuum-operated load compensation device.

    In practice, the installation of dual intake manifold on Fords and Mercury’s of the ’49 trough ’54 series should be accompanied by a change in distributors such as prescribed in the preceding paragraph. The addition of two carburetors divides the airflow so only half as much airflows through one carburetor as previously at normal operating speeds. Venturi vacuum is dependent upon the air velocity through the venturi so any reduction in velocity will result in less spark advance. And connecting a line to each venturi vacuum takeoff of a dual set up will not increase the vacuum---such a practice is just a waste of copper tubing. The best advice to keep in mind when purchasing a distributor is not to pinch pennies. An inexpensive unit, if it doesn’t do the job correctly, can prove to be the most costly. The best way to avoid mistakes is to study the problems involved and learn enough about them so that you can select a distributor that matches your engine requirements.



    ################

    Spreading the gospel feels goood ;-)
     
  23. 4T6 didn't you see the guy at Z-hills that had a basket-full of 94's for $20 a pop
     
  24. 286merc
    Joined: Mar 3, 2001
    Posts: 1,793

    286merc
    Member
    from Pelham, NH

    I guess i could be one of those gospel guys that 286´merc refers to. I dont understand how an article that was true in 1954 could be outdated? Im not aware of any changes of the 8BA distributor function since 1954?

    I never said that there have been changes to the distributor or its function, do you have a reading disability?
    Now, I'll give you a little hint since you appear to be a bit on the slow side. What HAS changed since that ancient article?
    Hint 2: The answer is in my tuning post.

    When you figure out the answer you can return to your "other" flathead site and tell the handful that still hang out there. Or maybe do a search on Fordbarn (the best flathead site) as it has been discussed there a few times.

    Spreading the gospel feels goood ;-)

    Debunking them feels better [​IMG]
     
  25. Mr 42
    Joined: Mar 27, 2003
    Posts: 1,215

    Mr 42
    Member
    from Sweden

    Woow touchy guy,
    Sincy you can tell my mental capacity, maybe you could tell me about my reading capacity to? ;-)

    I was not trying to degrade you in anyway, i just thought it could be nice to show the boys here the outdated article you refered to.

    And i still think the physics the Mr Navarro refers to still applies.And if i read right you agress to that to.

    The important thing here is to understand that the original distributor works from Venturi vacuum, and wont work with Manifold vacuum, and wont work with Stromberg carbs (since they lack output for venturi vacuum). And will not work with dual 94's unless tweeked a bit(or alot).

    Finaly yes you have upperhand on me since my first language is Swedish, and i can assure you that i dont get all the fine expressions between the lines. But i stll dare to say my thing.

    Regarding spreading the gospel you was the one refreing to that. And i was jut trying to be funny.
     
  26. 30roadster
    Joined: Aug 19, 2003
    Posts: 1,793

    30roadster
    Member

    mr42 and 286merc - both posts have been very helpful.... i've copied your posts and saved them to my hard drive...
    i've got 2 (94's) and at some point i'll need this info badly! - thanks a million! [​IMG]
     
  27. 286merc
    Joined: Mar 3, 2001
    Posts: 1,793

    286merc
    Member
    from Pelham, NH

    Mr 42, OK sorry about that. Since there is nothing in your profile I thought you were just one of those who still lives in the past on another forum. And just wanted to make trouble!!

    As far as why I feel that 1954 article is outdated is that the rodder did not have any choices when working with the 94. It has been referenced to many times here on HAMB as it is on Rumbleseats web site. Still makes good reading tho.

    Holley had not yet even developed its famous (infamous?) 4 bbl or 2300 2 bbl (those both debuted on the 57 Ford) and the rapid growth of the muscle car era was still 10 years away. Once that happened then a wide choice of power valves, and jets became readily available since Holley used the same PV and jet design as the old 94.

    I certainly agree, and make that clear in my article, that using the Lodomatic distributor IS a compromise but that as long as the shortcomings are understood it can be used with dual 94's.

    Another holdout from those ancient days is the concept of plugging the valves. Since there were no choices it was the only thing to do. These days anyone that has to run blocked PV's on a street engine has questionable carbs to start with. Now, Im refering to 2 and 3 carb street setups here, not some wild 4-6 carb setup on a nailhead, SBC, hemi or other OHV that is so overcarbed that the PV's have to be plugged just to get moving.
    Blocked PV's were also popular on the drag strip in ancient days, especially flatheads with 4 carb intakes. That was often simply a matter of too much carb for the engine coupled with a real lack of information sharing. These days we know better; I hope.

    So, back to rewriting the gospel for this century. [​IMG]

     
  28. Mr 42
    Joined: Mar 27, 2003
    Posts: 1,215

    Mr 42
    Member
    from Sweden

    Ok great, no harm done :)
    Some day i will figure out how to fill out the profile to.

    I agree with you on the PV stuff its important to get that working properly, and plugging is not the way to go.


    And you article is the first one after the Navarro that ive read that makes sense, so i will save that to....


     
  29. delaware george
    Joined: Dec 5, 2002
    Posts: 1,246

    delaware george
    Member
    from camden, de

    i just wanted to bring this back up and see if anyone has found out the reason for the hole...i just got a matched set of 8bas and one has a hole
     
  30. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,681

    Bruce Lancaster
    Member Emeritus

    Vent holes: No answers, but some observations.

    There was LOTS of fiddling with vents over the lifespan of the CG-Holley-Ford 94 and its relatives. I know very little about the post-48 ones, nothing about Y block and Holley aftermarket ones. I've worked with lots of the various 1937-48 types, including Lincoln and 92 versions. It is very difficult to say what pieces are original to a particular carb body, because most of these things have gone to commercial rebuilders who mixed parts and because Ford discontinued early models as each change appeared, eventually making the 59's the replacement for all.
    Vents I have seen: Some have an internal vent pipe running from inside front dome up into the bore. The earliest lacked the little slot through the wall between float and pump linkage chambers in the cover, and service bulletins from about 1940 call for this to be added by dealers and rebuilders. The earliest manual shows a tiny drilled hole at the left side of the hump covering the pump area. I have this hole on a single Chandler Groves carb only in my collection. Many but not all later carbs have the larger hole in the back side of the hump as shown above. The hole shown above is crudely done with the intervening casting web chewed up, but you can see in that pic that the web has a CAST notch to allow said drilling without collateral damage. Most carbs have this notch.
    On the LEFT side of the hump in the lid, there is usually a small oval depression cast into the metal. On many carbs, this oval is cut through as an extra external vent. These cuts all seem to be OEM, with the whole oval cut out perfectly neatly.
    The earliest CG/early Holley lit calls for a float setting of 1 3/8-1 11/32 on Ford with a fuel level of 11/16. Later books call for 1.353-1.322, still with 11/16 fuel level to result. Racer Brown writing in about 1954 said this float setting should be moved down 1/32 to 1/16 to stop percolation and flooding.
    What does all of this mean?? Good Lord, I don't know. It does seem to suggest that there were mixture difficulties blamed on pressure differential between the bowl and the rest of the world. It would be interesting to go to the archives and ask for the prints and engineering change orders on the upper casting to see what happened when and what reasons were given.
     

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