I've been chasing my tail getting the mill in my '39 Tudor running right for the last two weekends. Here's the story: Starting out, the motor is a 286 59A, Scat crank and rods, Ross pistons, new Edelbrock Heads, Red's Headers, Schneider 270 cam, and topped with a new Edelbrock Slingshot and two new Stromberg 97s. The carbs are on a strait linkage and were flow-sync'd with a Uni-Syn. Ignition timing is at 8-degrees initial. Initially, I got the car to run and idle perfectly with the stock mains (0.045") tuning with a vacuum gauge, the idle screws were 1 1/2 turns out. The car would idle fine, warm up fine, but after about 10-minutes of driving the idle speed would climb, and under load the car would stumble, and die. After limping the car home, I pulled a plug: The outer ring reads super rich, but the electrode looks lean. I ordered a scad of jets, and today I swapped the mains for 0.043"s. The test drive started very well, much better response throughout the throttle range, but only for about a half an hour. Then the same loading up, and dying. It happens now when accelerating after sitting at an intersection for a few minutes. Limped the car home a block at a time again. This time the plugs were rich, but not quite as crusty, all over. The electrode was more of a dark brown than a white as before. So, then I fiddled with the idle jets and settled with them 1 1/4 turns in. The idle, and return-to-idle is much better, although more lopey, but now there is an obvious miss on at least one cylinder. Pulled a plug again, still rich, but more of a burnt Carmel color, so I think I'm close. If I turn the idle screws in anymore, the car doesn't want to start easily. So, calling all Stromberg experts. I know I'm close, but I must be missing something. The last time I tuned duals had to have been 15 years ago...
Are you running air cleaners?? Small, shiny ones? Edit...is this a stock 59 or 21 type distributor, or what? Have you revved it up with a timing light on to sure that advance starts right off idle and keeps going up...? Lack of advance imitates some carb symptoms...
The carbs are the new "genuine" Stromberg 97s. I am running frog mouth scoops with the little screen and foam 'filters' if you can call them that. Advance is set at 8-degrees initial. It is a stock ford crab-type. I haven't verified the advance since I originally got the car running. I'll throw a timing light on it tonight. Fuel pump is a little Carter 6v regulated through a Mr Gasket regulator set to 2 lbs.
Hope I can help on this issue which sounds parallel to my own ........just on road with my 39 w/flathead built w/same components as yours except for 3 carbs new Stromberg 97 English repop's using progressive linkage.......killed 3 sets of plugs in 300 mi and experienced similiar running issues to yours.......finally called Uncle Max and a 10 min talk got me squared away...... Firstly, take off carb tops & ensure your float levels are not too high, ie, float top will bottom out on carb top......this will cause the new carb's checkball valve to remain slightly open with end result of puking raw gas down carb throat......creating driveability issues as you outline...... Had to re-jet and replace all power valves......center primary carb is now 43 jet w/6.7 p/valve and end carbs are 42 jets w/7.0 p/valve......still need to adjust using vacuum gauge on carbs and fuel air screw adjustment, still using my initial settings so I can assess each change........have put 145 mi on carb changes and plug readings are lite tan, no sign of previous richness/raw gas, runs great & pulls well ........haven't had motor over 3,000 yet, so no full throttle yet.......
Remove those scoops with the tiny filters and screens and give it a test drive. Those little filters have less area than the one on your lawnmower, and can probably plug up worse in 10 miles. Try it. Also, at some point T in a pressure gauge of respectable manufacture and check pressure....the little round regulators with built in gauge are frequently badly mistaken about their pressure settings! But first, get those things off the tops of your carbs for a road test!
Okay, so after a few nights worth of checking everything, here's where I stand: Checked fuel level in bowls - Exactly right on, 1/2" with pump pumping. Checked fuel pressure - a little high, 4lbs. with reg cranked all the way down. Have a new Holley reg on order. Checked vacuum - fine with gauge hooked into wiper port in intake. But when wipers are plugged in, engine races. Disconnected wipers and plugged port. Checked Timing - checked with vacuum. Engine most comfortable at stock timing (4 deg initial) plus two notches on the adjustment scale (59A distributor) I think this means 8 deg total initial timing. Checked Points - gaps are right, but a little burnt. New points on order. Checked Plugs - gaps are all correct per factory specs. Checked coil - rings out fine -BUT- gets really, really hot after a few minutes of running. I think this might be the culprit. Yesterday I called all the local parts places for a new UC14 coil (6v internal resistor) and found one in stock, to replace the unknown 6v coil that was in the car when I bought it. I bypassed the factory restistor under the dash, as it is not needed for a UC14 and I wanted to isolate the resistor as a potential problem. After I installed the new coil, crank and no start. No spark. Rang out the new coil and it was bad out of the box. So now I have all the aforementioned parts on order, as well as another coil, a new, better carb syncronizer, and enough sizes of carb jets and power valves to tune any Stromberg I might come across. This tuning by mail order is killing me, but I'll have enough parts on hand for the next go-around, or seven.
on your idle jets start at 1 1/2 turns out, turn each one in until she runs rough then back out 1/2 turn your done. x2 on getting rid of the filter
I'm not an expert on flatheads but it has been my understanding (right or wrong) that the earlier generation flatheads are supposed to use 94s. Is this wrong? Also, from the poster's initial details it appears the motor is not "stock" and therefore the factory timing, etc should only be a starting point, yes?
@56shoebox "Early in the '34 production year, Ford decided to replace Detroit Lubricator carburetors on their V-8 engines with Stromberg 40s. The similar 48 model replaced the 40 as the standard carb in late 1934. The 97 appeared on the '36 models and continued through early 1938 on the 221-cid flatheads. The smaller 81 carb was used in 1937 and part of 1938 on the 136-cid V8-60 engine. In the middle of 1938, Ford switched from Strombergs to Holley 94 carburetors." Copied from Hot Rod Magazine. The 97 was an "economy" replacement for the larger 48, and the 94 was a cheaper alternative to the 97. The 81 was essentially a mini-97. You can use any on any mounting pad that'll take them provided the CFM of the chosen carbs match your application.
And yes, as my motor is far from stock, the stock settings are just the starting point. Thus the fact that the motor pulls the most vacuum with 8 degrees initial advance rather than the stock 4 degrees and so on... And since this thread is worthless without pictures, here's the motor in question: (Carb linkage and wiring not completed in this pic, and the coil is in a different place now)
43 main jets will be WAY too lean when you get it running right. You should be around 48. The stock power valves should be ok. Be sure to SOMEHOW check the fuel pressure at FULL LOAD wide open throttle. Very few small electric pumps will maintain pressure at full demand. Your inlet plumbing leaves something to be desired. You should have separate feeds to each carb for equal fuel delivery. This requires a fuel block.
if you are using a vacuum gauge to set timing go to max then back off 1" of vacuum, max vacuum will be too far advanced
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