low speed surging

[moose]

Salutations to the Brain Trust,

You Folk are ALMOST always up with correct tech assistance!

I have a low speed surge issue in my 36 Sedan. 300ish horse Jasper street engine. 350 Chevy, 500 cfm Edelbrock preformer, 15 inches vacuum, have the sliver step up spring installed, Pertronics Blaster dist with the correct coil. 350 TH trans, 8 in rear with 2.79 gears. at off idle and up to about 35 mph I have a surge/stumble if I let the trans shift in drive I am in third at about 25 ish mph. If I drop the trans down to 2 the surge goes away. It starts and idles fine.

Am I just under geared, under carbed, any direction to correct this?

Thanks
moose

[chimp koose]

Problem goes away when shifted down a gear . Maybe low float , stumbles when transitioning from off idle to main circuit ? shifting down will run up the rpm with the same throttle position causing more vacuum and fuel to get flowing in the booster venturi . Just a guess could also be retarded timing . Check out ignition before adjusting carb . Lots of 'carb problems ' are found in the distributor

[enjenjo]

I believe that a higher numerically rear gear will cure most of your problems. I had  similar drivetrain in a 47 Ford with a similar problem. To test it, block the vacuum advance and the surge should go away, or at least get better.

In my case a  change to a 3.25 gear cured it completely. Remember the cars that came with a 2.79 gear had much shorter tire than what you are likely using.