The Stovebolt Site Forums The Shop Area Engine Shop 1955 Chevy 235 Acceleration Issues

Hello All! I need some assistance. I've finally gotten to the place where I have my 1951 Chevy Truck ready to drive and it's giving me fits. The 235 was bored .060 over and has been rebuilt completely. I also have rebuilt a Rochester Monojet carb for this motor. The truck will start and idle fine. I think it would run at idle until it ran out of gas. But when I try to drive it and get it under load, it really falls on its' face and I can get very little speed. Can someone please offer some words of advice as to where I should start to try and diagnose the problem? Appreciate the help in advance!

Hy ChevyTruckKy, have you checked your fuel pressure, and fuel delivery rate? Other than that float level may be too low. Does it just seem to die out, like it has run out of fuel, or does it misfire and buck and snort?

How is the ignition timing...?

That's my first thought as well.

Hey 3B and Longbed61... I have not checked fuel pressure and fuel delivery rate nor do I know how to do this. It just wants to die down it doesn't misfire or buck or snort. The timing is set just a bit advanced and the motor starts fairly easily so I'm not sure that is an issue or not. I need to get a timing light and check the timing as well I suppose.

I am not a veterain six tuner, but that problem often shows up for small block guys with the 20 degree vacuum canister on their HEI when they hook the vacuum advance to raw manifold vacuum and set their idle and ignition timing without realizing they should have set the timing with the vac advance disconnected. The problem is when they release the clutch and the vacuum falls, thier timing is gone and now very retarded under load. I am not sure whether or not this is possible on a six?

Longbed61, very interesting points regarding setting the timing with vacuum disconnected as I did not set things up that way. Can anyone with some 235 6-cylinder experience confirm that timing should be set with main vacuum disconnected?

You always set initial timing with main vacuum disconnected and plugged no matter what motor you're using.

What year 235?

I have never disconnected (and plugged) the vacuum advance line on a 1954 and later 235/261 engine when setting the timing at idle (but, doing that would not harm anything).

http://chevy.oldcarmanualproject.com/shop/1954truck/54ctsm0619.html

http://chevy.oldcarmanualproject.com/chevyowner/54tom31.htm

Here are the 1948-52 instructions:
http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0619.htm

Here are 42-47 instructions:
http://chevy.oldcarmanualproject.com/shop/1942_47/4247csm632.htm

I recall disconnecting/plugging the vacuum advance line for timing adjustment back in the late 60s on a 1948 216 engine. I did what I was told to do. I do not know if that was necessary.

Tim,

It's a 1955 235... So would your 54 guidelines be the best to follow?

That's what I have always done on my 1954 and later 235/261 engines.

I have used that procedure on 1954, 1955 325s and on 1959, 1960 261s.

BY the way, I have found the easiest way to set initial timing is to put a vacuum gauge on the wiper-motor pot on the intake manifold and then set timing to the maximum vacuum at idle.

Harvester suggests another good way of setting timing using a vacuum gauge and a tachometer.

Other people (Hotrod Lincoln is one) have posted another procedure that sets the timing advanced to the point that pinging occurs upon acceleration, and then back off by one degree (or, degree-by-degree, until the pinging upon acceleration is gone).