Hesitation taking off at low RPM

[rkdinuzzo]

Hey all- '57 e-code here. Car starts and idles very well, but have been having the annoyance of hesitation (almost to the point of stalling) when I first press the gas to take off from a stop around 2,000 RPM). Goes away as RPMs increase and pulls quite well at high RPM.

Thoughts on where to troubleshoot? Gas is fresh, spark plugs are good and properly gapped, so thinking perhaps something in the a/f ratio? Input would be greatly appreciated.

RD

[MarkR]

Could be several things but I would suspect accelerator pump.

[ward 57]

Could be several things but I would suspect accelerator pump.

That was my first thought also.

[paul2748]

What initial advance are you running ? Y blocks seem to run better around 10-12 degrees. This MAY cure the problem.

[Jimntempe]

Can you clarify the "take off from a stop at 2000 rpm". Is it a stick or automatic?

[ward 57]

Can you clarify the "take off from a stop at 2000 rpm". Is it a stick or automatic?

My question also. 2K rpm sounds a lot high at a stop. Dual quads especially with the teapot carbs are known to be finically. many have been converted to a newer single quad carb for that reason.

[willcarter]

I spent the first couple of years that I had my ‘57 trying to diagnose and fix a similar issue. Background info here: viewtopic.php?t=20407&hilit=Float

And ultimate solution here:

http://vintagethunderbirdclub.net/phpBB ... 56#p132102

In sum: I’d very strongly recommend you start by checking your float levels before exploring the other possible causes. Had I done so, it would have saved me a great deal of effort and angst.

Of course, your issue might not be exactly the same as mine; and even if it is, there are, as others have noted, many other things that could cause it. But if I had checked the float first as several folks here suggested, I would have saved a ton of time. I don’t know why I didn’t do so in the first place: in retrospect, I think it was because adjusting the float on my carb requires removing the float bowl, and messing around with raw gas makes me nervous; plus, it almost seemed too simple that adjusting the float with be the solution. But I can indeed now say that at least on my carb (an era-correct Holley 1273-1), adjusting the float even a little bit makes a huge difference (and therefore also that if your float level is even slightly off, that will also make a huge difference in my experience).

[rkdinuzzo]

Thanks for the input, all. Going to start with replacing the floats and the accelerator pump and see where that takes me.

[paul2748]

Unless there is fuel in the floats, no sense in replacing them

[ward 57]

Unless there is fuel in the floats, no sense in replacing them

I was thinking the same thing. They are adjustable by nature. Please people, resist the urge to replace ( inferior parts ) and instead repair/ adjust. You won't regret it and maintain original equipment which is much better.