Model B Motor won't Rev past 2200RPM

[Ron W]

If nothing else works, check valve timing. Ron W

[jim1932]

what are you using to feed gas to the carbs? didn't hear mention of a fuel pump.

[MikeK]

Flat cap Mallory? Crab type caps are notorious for stress cracks and resultant internal arcing causing exactly what you describe. Try a different dizzy.

[Ron W]

Please let us know how you finally solve the problem. It helps everyone. Ron W

[Big hammer]

Originally Posted by Ron W

Please let us know how you finally solve the problem. It helps everyone. Ron W

A-BONED I have been following this thread, wondering if you have had time/luck with your problem :-)

[dsarge390]

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Check that the coil leads are on the correct side. A reversed coil will run until you put it under a good load...something that could be overlooked. Also, check distributor gear. may have broken a tooth off. Happened to my A once. Ran good until she revved up.

[d.j. moordigian]

Originally Posted by A BONED

No good on the ignition wiring. Took her out for a spin and she's exactly the same, hit 2200rpm and it craps out. Some people have suggested weak valve springs causing a valve float issue. I've recently had this little mill rebuilt with modern stainless valves, one piece guides, retainers, locks, and springs. It's recommended that 60Ibs on the seat for valve spring pressure for a mild performance cam is good, stock they are around 32Ibs, using modern valve setups like I have reduces the spring pressure further.

The only thing is I don't hear any real noise when the thing craps out at 2200rpm. It's just like it's on a rev limiter and misses repeatedly. With valve float typically there's mechanical noise from where the lifter has come off the cam lobe and smacks back down on it. Still chasing my tail here...

Just how much spring pressure DO YOU HAVE?

Questions..When it reaches 2200rpm;
1. Does it start "shooting ducks"..?...backfiring?
2. Do you see a "fog" out the air cleaners?...making this sound "baaaaah" ?
3. You should check the points for GOOD spring pressure,...it's a limiter!

With "valve float", you MORE THAN LIKELY will not hear any valve train
noise..

[A BONED]

Just an update for those that may be interested. No luck as yet with the issue. I've tried a new coil, and have also adjusted valve lash and pulled the timing cover off to verify that the cam and crank gear line up.

It seems that Jim Brierley's suggestion that I have a valve spring issue may be correct. I've tried contacting Charlie Yapp on the SOSS website to get a set of 3/16 valve spring spacers with no reply at all. Does anybody know where I can get a set of spacers or another set of appropriate valve spring? I'd really appreciate a heads up.

[Synchro909]

I suggested in Post #2 that you may have a broken valve spring - same as a weak one. A second hand one would do just fine - plenty of those about or check Brattons:
VALVE SPRINGS
Part #: 9290
$6.15
You'll need 8 if you want to replace the whole set.

[aonemarine]

remove hood, sit some dumb (insert) on the running board with a can of 2+2 and when it acts up give her a shot and see what happens....

[rally 1]

The one piece guides lack the "flange" that is on the two piece guides for the spring to hold it in place.
A shim (3/16" or so) is required to bring the installed length back to spec. Might consider making the shims 3/8" to give a little more pressure.
Ken

[CarlG]

The one piece guides that came with the Snyder's "modern" valve kit have the flange.

[Dave in MN]

"It seems that Jim Brierley's suggestion that I have a valve spring issue may be correct. I've tried contacting Charlie Yapp on the SOSS website to get a set of 3/16 valve spring spacers with no reply at all. Does anybody know where I can get a set of spacers or another set of appropriate valve spring? I'd really appreciate a heads up."

A BONED,

The last time I checked with Charlie, this past winter, he did not have any spacers. He was considering making/offering them.

I turned a set of them on my lathe out of used exhaust manifold washers. I drilled them out to slip over the one piece guide and then flattened one side to allow for good spring contact. They end up seating on the top of the valve chamber roof. You could do the same thing with a couple correctly sized washers on each guide.

If you do this, make sure you do not bind up the coils when at full lift on the valve. Turn the engine over by hand and check or watch each valve spring as it reaches full compression.

I left them about 3/16" thick and they works fine with AER springs. (Antique Engine Rebuilding)

Good Day!

[hardtimes]

Well, I've stayed out of your thread, as I saw early on that you got , most likely, the BEST answer from Jim B ! For some reason, you've not acted on his advice/opinion of your problem.
Isky makes V8 flathead springs..new ! Those are the springs that I've used and set valve seat pressure at 75 lbs.
Again, if you do not look into the advice of one of most, is not the most , experienced member's advice...well

[rocket1]

I had a coil on my 50 olds that would break up the engine when reved,figured this out after replacing fuel pump.

[A BONED]

Originally Posted by hardtimes

Well, I've stayed out of your thread, as I saw early on that you got , most likely, the BEST answer from Jim B ! For some reason, you've not acted on his advice/opinion of your problem.
Isky makes V8 flathead springs..new ! Those are the springs that I've used and set valve seat pressure at 75 lbs.
Again, if you do not look into the advice of one of most, is not the most , experienced member's advice...well

Thanks for your post hardtimes. It's not that I chose to ignore Jim Brierley's comments, it's just that I wanted to rule out other possibilities before having to tear into the motor to replace valve springs. Most of you guys know far more than me, especially someone as experienced as Mr Brierley. That's why this forum is such a great resource.

Chris.

[A BONED]

Originally Posted by Synchro909

I suggested in Post #2 that you may have a broken valve spring - same as a weak one. A second hand one would do just fine - plenty of those about or check Brattons:
VALVE SPRINGS
Part #: 9290
$6.15
You'll need 8 if you want to replace the whole set.

Thanks Synchro909, I should have also stated that I've had the valve cover off and visually checked the springs to see if one was broken. All the springs are installed correctly with no obvious mechanical issues.

Chris.

[Synchro909]

Originally Posted by A BONED

Thanks Synchro909, I should have also stated that I've had the valve cover off and visually checked the springs to see if one was broken. All the springs are installed correctly with no obvious mechanical issues.

Chris.

Hmmmm, The "Thlot Pickens". As somebody has already requested, please let us all know how you fix it.

[bykerlad]

My bet is its fuel,when you get up around 2000rpm introduce a little more fuel down the carb and see if that makes any difference.you have received lots of good advice (lots of good advice on here ) but it's nearly always the simple thing that causes the biggest problem.

[A BONED]

Thought I should put up a final post on this issue. My little banger is now running like a Swiss watch. I had previous tried another distributor with no success at all, I had an old model B dizzy in the shed that caused the mill to run like a dog. Anyway, just recently I was able to borrow a nice later Mallory points dizzy from my mate Bikerlad with some great results.

My little model B mill idles great, and revs clean, way past the 2,500rpm mark. I'm pretty sure there is something wrong with the mechanical advance on my old cast iron flat cap Mallory distributor. I've had the old Mallory apart and it looks great on the inside, no broken advance spring, everything looks clean and free, but I'm sure something isn't quite right. Thanks to everyone that offered good advice and information, thanks to Bikerlad for all his assistance.