Technical B engine issues

First off, a little about the car. It is a late '31 Coupe w/ indented firewall with a B Diamond engine, stock tranny and rearend w/3.78 gears plus a Ryan Overdrive with 26% overdrive, '46-'48 Hyd brakes and 16" wire wheels. Front spring has reversed eyes. Body was done 30 years ago by someone else and car was never finished or driven. Set around until the tarp over it burned away by the sun over the years. I pulled it all apart, straightened and fixed frame issues, redid all the brake plumbing and new m/c, new wiring, new dropped headlight bar, etc, etc.

Engine had been gone through and reported to have been drilled for full pressure to rods as well. Engine has the Glyptol coating inside. Has Model A manifolds and carb (Zenith). Stock Model B head with the big "C" on it. Fuel pump blocked off. It had an electronic distributor when I got it but parts were missing so I put a rebuilt A distributor in it with modern points. The engine pulls hard on low end but is weak on top end. Timing has been set and verified a thousand times, have had 3 carbs on it, and 2 or 3 intakes and exhaust manifolds, 2 different Model A mufflers. Setting in neutral and revving the engine it wants to stutter and spit back through the carb. It ran like the cam timing was off a tooth. I pulled the cover and timing was right on but found many of the teeth on the fiber gear were mostly missing! So, in goes a new aluminum timing gear and rope seal and new 1 piece crank pulley. The 2 piece one that was on there had the inner part flopping on the crank! China crap. Crank was not hurt at all as it had just a 150 miles or so on it at that time. Put it all back together and nothing changed. I have a B intake which I tried and a borrowed good running B carb that runs smoother but still doesn't fix the problem but will go back on it soon for keeps. I have also adjusted the valves which were a little tight and now they are on the little too loose side. Better to hear them than smell them burning huh?! Plugs look perfect. New Dist cap/body/rotor. New coil, correct polarity. 12v alternator. Leakless B water pump. Tonight I put a stock B distributor on it. Still spits back through carb. Seems to run just a touch better on the road and nice not having to futz with the timing lever. It pulls better in overdrive than it does it straight through. I have not had the head or pan off this B engine but that is about the only thing I haven't redone or checked.

My 31 Roadster pickup with A engine and a 5.5 Snyder head with nothing else modified will blow it away. Heck, my 27 T Roadster with a 6-1 Z head and a 3-1 Ruckstel rear end has more top speed than the Coupe with the B and I know that's not right.

Any ideas guys what the heck is wrong?

Oh yeah, a couple 3 weeks ago we went on a covered bridge tour in the Valley (Lebanon, Sweet Home, etc, Oregon) and I was 3rd in line. Fella leading has a 29 Tudor, very nice car, Overdrive, etc. Near the top of 1 big hill he nearly stops and my friend in a 29 Dodge DA Coupe has to hit his brakes and so did I but on over we went. After we stopped, the leader asked me what gear did I pull that hill with. I told him 3rd overdrive. He about fell over and said he had to go to 2nd straight through and now he really had to do something apparently! So what I am getting at there is how well it pulls on the low end.

Help!

Thanks,
Dave

 

I woud say Lean!!! Plugs May look OK BUT with out a Wide band O2 gauge You cannot read plugs on pump gas of today ,,,,it's different blend of the old days
I worked on a car that pulled good 1st. ,,,2nd fell off,, 3rd spit spotter and Pop

 

Just curious, are you using a fuel pump, or just gravity feed ?? Are the fuel lines all clean/not blocked?? Does it make any difference if the full cap is left off??

 

Yes would check the filter in the fuel tap and make sure enough fuel is reaching the carb There are better dizzies than that stock one around nowdays

 

Gravity feed to stock carbs, lots of fuel flow with line removed from carb. I keep going back to cam problem, that's what it acts like but cam timing is for sure correct. Multiple carbs and distributors, caps, etc. Nothing has changed it's spitting back through the carb when revved. Was even thinking stuck valve but each cylinder when plug is grounded out, slows idle speed a lot and evenly. All valves move up and down as well as evidenced when setting the valve clearance. Yes on better Distributors but I don't want to run an electronic one. Haven't tried with gas cap off, I will do that.

 

Are you timing it with the pin in the front cover ? You might have a Model A cover on your B. The A and B covers have different timing pin locations.

 

What oil are you useing , You need to have zink , it's possible you have a cam going south ,
I sill tink Lean on """ Air fuel ratio """

 

Yes, I know about different timing covers. It is a B engine with B timing cover and I also have a timing tag on it. Timing with A dist set at TDC, B dist gets set at 15 degrees BTDC.
Oil is fine, DELO 30W. Engine was rebuilt previously but not by me. B carb is from a great running car. It is a touch better but mostly just at idle.

 

I would advance the timing to what the B dist gets set at. try it.

 

I am up on the zinc issue but if you talk to the banger gurus they tell you that isn't an issue because the cams are steel, not cast iron like later cams. But I lean towards better safe than sorry. Plus not much spring pressure on these with stock springs and cams. That's not to say this isn't a cam problem but I don't have anything to say it is yet at this time.
The search continues. I am going to switch the intake back to a B manifold soon (which I tried before and made no difference) and when the manifolds are off I will re-adjust the valves. Right now they are a little too loose for my tastes. I set them by what I read online, fordgarage.com if I remember correctly and seems like that might of been in error. I am told the setting is different on the B cams than A cams. What should a stock B valve clearance be?

 

I'd do a positive stop on #1 piston, MARK the pulley at true TDC, hang a degree wheel on the crank; then remove side cover and read the cam timing. Sounds like the cam is 'early' (advanced)
I recall that there was some reason an 'A' or 'B' cam was 'out of phase' after grinding. (was it the cam grinder that indexed it differently than conventional grinding? Or was there a different indexing in a cam that otherwise 'fit'?)

Everyone looks for incorrect cam timing as being "a tooth off". Count the teeth. One tooth off and the engine wouldn't run. Check for a minimal cam timing error. One that is 'ground' or 'keyed' in.

 

Been there done that on marks. My first thought was cam timing off but it wasn't. Gear was crappy so I put new Aluminum cam gear on. No different. As far as not running with one tooth off I have to disagree. I put a gear on several years ago on a '29 tudor I had that ran like this after new gear. Drove it 300 miles on gravel mountain roads that weekend and when I got home I opened it back up and sure enough I was off 1 tooth. Set it correctly and ran like it was supposed to.

So Mike, can you elaborate on how to check for "minimal cam timing error"? the marks on the crank gear and cam gear lined up. How to I read the cam timing with side cover (valve cover?) off?

I am also assuming it is a stock B cam as it was rebuilt before I got it. MANY years ago but car was never finished and never ran. I agree, seems like cam timing to me and always has.

This is a 1937 Diamond B engine.

Oh, thanks Mike for the reply.

 

I have tried ignition timing all over the place and that doesn't fix the issue so I set it back to the correct initial settings dependent on which dist is in it.

 

Is it possible the carb blade is pass the transfer stot,
Sice the motor is a biger then stock , if so drill like a .100 hole ( in blade ) to see reajust idle & mixtures, just a thought

 

Nice looking coupe.
add, high compression head, fuel pump, B dizzy and more carb then you will get the performance of your other cars at high RPM (they all have high compression heads)
After that, give haircut to reduce frontal surface area

 

Does making it richer using the knob on the choke rod help?
http://www.zucksrototillers.com/ZenithCarbAdjustments.pdf

 

No, it doesn't.

 

Just a thought, I did an o/t Olds one time that had similar symptoms. Turns out the shop that did the rebuild did not check the valve spring tension. The car would run very well at low to moderate speeds but nose over under load or high speed. Replaced the valve springs and problems disappeared.

 

I think you need to pull the cam to see what it is.

 

Jim Brierley of 4 Bangers! and Me! told me kinda the same thing. He thought maybe it had modern valves and guides and those don't have the base on them where the spring sits so maybe they forgot to put a big shim under the springs. It will get torn into soon to check that out. A big THANK YOU to all that have offered suggestions. I will post the findings , assuming I find them of course!

 

The procedure to check absolute cam timing is simple in theory: A degree wheel AFTER true top dead center is found and marked on pulley. (at reliable pointer fixture, or stock one if it is permanent.)
Set the piston at TDC. Adjust degree wheel to ZERO. Now, clamp a dial indicator (0 to 1" range) so it is indexed on top of #1 exhaust tappet. With an assistant at the dial indicator, turn the engine over slowly, until your assistant sees the dial move. Record the number in degrees on the degree wheel. Now continue turning, until the dial reaches its maximum height. Record the height measurement, AND the reading on the degree wheel. Resume turning, until the 'event' is finished, (dial indicator back at 'Zero', tappet down) Record how many degrees before top dead center it is.
Now, reset BACK to BOTTOM dead center: This will necessitate turning engine backwards some 90 +/- degrees at the wheel.

Move the dial indicator to the intake tappet, right next to the exhaust you just did. As the intake event occurs right after the exhaust, (actually 'overlaps' it, so both valves are 'up on step' at the same time) but as we do one at a time, the overlap value will be recorded in your notes.
Now, from BDC, turn the engine until your assistant sees the dial move. It'll be some 30+ degrees, but we should be safely outside where the tappet will contact the ramp of the cam. We MUST be sure we get the whole 'incident'! Record the event just as before, noting maximum height and its degrees just before top dead center. When the intake tappet comes down, it will be just before Top dead center. The intake event is now finished, and hopefully recorded.
This is an operation that's easily performed, but difficult to choreograph!
The method is the simplest way to merely get the 'moments', and that's what we're after.
These values can be read off a card/page that has your cam data. When you compare them, bear in mind that the cam MIGHT be running advanced. (sounds like that to me)
When you read your notes, IF you used 'positive stop' method to index true TDC, the values will jump out at you.
I'm particularly aroused with, "Engine was cammed at an earlier time, but never ran"
Hope you find it, wish you were closer.
(Or the exhaust is plugged with carbon...Don't laugh, I've seen 'em plugged SOLID! ...... the ol' 'Potato in the exhaust pipe trick!)
Please check the cam and its timing, it will make for a complete diagnosis.

 

Mike, I used to own a motorcycle shop and have seen several plugged exhaust. Mostly small moped kind of stuff. Pulled exhaust off and the ran great. I did check that on this one.

I will print out your instructions and give that a try if I don't find the valve spring tension too low. May do it anyway as I think that will tell me about the cam and what it might be.

Thanks,
Dave

 

Glad to help, Dave. As you are a former M'C shop owner/operator, I am trustful that you are like I, a 'collector of useful, applicable info'.
Glad to help.

 

Well, problem still exists. I pulled some valve springs and they check out for height and spring pressure. It has stock mushroom stem valves, split guides and retainers. Readjusted valve clearance, nothing has improved. Now no. 2 cylinder has a definite tic which sounds like too loose of a valve but it goes away if I ground out the spark plug. This engine is about to be pulled out and torn down to see what the heck is going on! I have a spare Model A engine I am gonna set up on a stand and run it and see what shape it is in. It came out of a running car that his son decided to hot rod. If it runs ok, it is going in the coupe and the B engine will get gone through with a fine tooth comb. I am really wanting to do a lightened flywheel and V/8 clutch, little bit more cam, maybe intake and carb and bigger exhaust. Guess I will see where I go from here on this one. For now, back to my '29 AV8 Sedan resurrection.

Dave

 

This one pissed me off so bad I have yet to do a thing with it. I am retired as of June 15th so after Bonneville Speed Week it can get some attention. The AV8 is my high priority for now.

Dave

 

As you know, the stock "A" distributor does not have any automatic advance. Timing must be adjusted by the lever on the steering column. The "B" distributor has flyweights to advance the timing. Have you watched with a timing light to see if the timing is advancing properly as rpm increases ?

 

I did some work on this B engine and found some things. The knock was still there, but not 100% of the time. Seems to come and go at will. As I said earlier, I changed out the timing gear with an aluminum one because the fiber one was shedding chunks. I dropped the pan and found the oil pump screen was 99.999% plugged with timing gear fiber! Oil pan was full of the crap too. Cleaned all that crap up and also pulled all the rod and main caps. Turns out this has insert bearings which I was told it had been drilled for full pressure to the rods. Not so! Bearings are nice shape though quite a bit narrow for my taste. I plasti gauged them and all rods were a thousandth and a half. I now believe the knock is the rod big end side to side movement since they no longer have babbit thrust on the sides. I took this car to Bonneville speedweek and have been driving the daylights out of it. It continues to run better and better the more I drive it. Knock/rattle is still there when it wants to but I no longer worry much about it. One other thing, the cotter pins in the rods and mains were mostly gone. I have seen cheap Harbor Freight type China garbage cotter pins break from vibration fatigue and I will not use them. I always use Dorman cotter pins and have never had one fail. That's what this has now. Nothing was loose but ya never know when it will happen.

I am running a B distributor, found one I tried had springs that were way too loose. One it it now works great. I am also running the B carb that I was finally able to buy from my friend that loaned it to me!

Now the biggest pain is the so called "leakless" B water pump from Macs. It has leaked from day 1 and no matter what you try according to their instructions it still leaks. I am this close to buying a Snyder head and Model A leakless pump it is not funny. It seems Mac's no longer lists the B leakless pump. Gee, wonder why?! Every time I order from them something is either junk or back ordered for months.

Thanks guys for all the help and suggestions!
Dave