1930s carburetor question

[MrTube]

So I've noticed something with older carburetors, specifically the Zenith on our A as well as whatever fancy carb is on this supercharged Duesy.

As heard in this video when the engine is revved and the carb is closed fast the engine stutters / misses.

http://youtu.be/QOQFDxRPdWM?t=37s


Is this because the mixture leans out momentarily and if so why? What changed in more modern carbs to stop this?

[1931 flamingo]

Automatic timing advance, power valves??
Paul in CT

[jmeckel]

If you have a stock A, try opening the GAV just a little more, should help. Assuming your carb is working proper with the proper jets, no air leaks around carb to intake or intake to engine.

[Gold Digger]

That thing sounds like a threshing machine running! I'd like to have it though.

[MrTube]

Originally Posted by Gold Digger

That thing sounds like a threshing machine running! I'd like to have it though.

Straight 8 DOHC 32 valve super charged 320HP right from the factory in 1932.

Sorry, I love Duesys and can say without a doubt they are my dream car that I will never have.

This is riding in a stock 260HP 1929 model, no supercharger. Huge difference from a stock model A, of course also a huge price difference.
http://youtu.be/B7XNCRC5wpk

[MrTube]

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Originally Posted by 1931 flamingo

Automatic timing advance, power valves??
Paul in CT

Good point, didn't think of the power valve \ accelerator pump. I *think* the Duesy has automatic timing advance though I'm not sure how good.

Originally Posted by jmeckel

If you have a stock A, try opening the GAV just a little more, should help. Assuming your carb is working proper with the proper jets, no air leaks around carb to intake or intake to engine.

I'll try that next time we have it out. Thanks!

[Growley bear]

"Modern" at least into the '70's engines will shudder upon rapid acceleration and rapid deceleration because of weak valve springs.

Chet

[Randy in Illinois]

Mr tube, impressive car, love them too,but i couldn't. Afford one. I dont think aoutmatic trans wasn't. Availiable until 1939-1940 . The noise might be a relief valve to let the pressure from the supercharger. Out of the manifold , to prevent intake manifold explosion. Much like todays high performance tubro/ or supercharged cars. Thanks for shareing, what a great car, said to do over 60 mph in sevond gear.

[MrTube]

Originally Posted by Randy in Illinois

Mr tube, impressive car, love them too,but i couldn't. Afford one. I dont think aoutmatic trans wasn't. Availiable until 1939-1940 . The noise might be a relief valve to let the pressure from the supercharger. Out of the manifold , to prevent intake manifold explosion. Much like todays high performance tubro/ or supercharged cars. Thanks for shareing, what a great car, said to do over 60 mph in sevond gear.

Perhaps you're right, the non-supercharged version doesn't seem to do it.
That is of course assuming all of the ones I've seen are running right, and being a multi-million dollar car I'd hope they are. I've also yet to find a "modified" one anywhere.

This is a non-supercharged version revving.
http://youtu.be/yHyNTe4Kue4?t=2m1s