Been servicing this 3 speed 1954 Chevy, for quite some time. Been over the whole car top to bottom. Engine is original 235 with like 100k miles Bottom line...under acceleration, it spits and sputters, like a lean pop/backfire, out of the carb. Power seems to be way off, won't accelerate very well, at all. List of service work in no particular order Fuel pump, tank, carb and inline filter all done within last few years. Vacuum advance also Ignition wires New spark plugs, points n condenser tonight. Compression test good Vacuum test good: 20 inches of steady vacuum at idle Swapped coil from other good running 235 with no luck Dwell at 30 Timing ??? (Hard to see indicator, on flywheel ) Thinking possible worn distributor? Does move when accelerated Swapped coil from good runner, no change ???? Sent from my iPhone using The H.A.M.B. mobile app
I am wondering if its fuel not ignition. Could always take out dizzy and check for wear. GMC Bubba is your friend of you dont feel comfortable with the distributor. Otherwise the carb accelerator pump could be shot. that would cause the power loss and sputter. What carb is on it? I guess check spark first then fuel
If you've changed points you've likely changed the timing at least to some degree. It's worth finding the timing mark on the flywheel so you'll know if your timing is way off or not. Does it act up when the engine is hot or cold? No difference? Does the choke work properly? Does it open fully when the engine's at operating temp? Is the backfire thru the intake or the exhaust?
ClayMart, had trouble seeing the pointer last night I usually have a 2nd 12volt battery I hook my timing light to. Going to try the old method of test light hooked to points and roll engine over, till light goes out. Did I mention vacuum was a rock steady 20" ? Hot or cold. Choke works fine. Daytona Carb did resto on both cars carbs Through the intake/carb Would a exhaust manifold leak have anything to do with it ???!? Sent from my iPhone using H.A.M.B.
Can the slop in the timing, chain be checked by rotating the crank by hand, and watch the rotor in the distributor?
I don't think the 235 has a bolt on the balancer. Regarding the timing, once the hole is found, that's just a starting point, usually will need/can take, more advance. If memory serve, points should be 14-16, unsure how that translates to dwell degrees, tho.
"Los_Control, Thats what I was thinking. I had a 57 chevy P.U. truck with that problem and it had slop in the timing chain. Bruce.
My 235 in the 55 had similar habits, until I found the vacuum canister on the distributor had gone bad. This resulted in " lean popping" through the carb because of the vacuum leak caused by the ripped diaphragm and power loss caused by the not working vacuum advance.Let the car idle and see if the distributor turns when you hit the throttle....
Yeah Bruce, some of those old fiber gears would wear and give the same symptoms. Remember those damn things???
thanks for clearing that up, I was not sure how the 235 timing was setup. With the motor having ~100k miles, it might be time to look at replacing the gears for simple maintenance. But doubt is the current problem.
Sounds just like my 302 did when I had the firing order all jacked up. Idle was good, didn't have much power, popped and banged under power.
Hey Fellas, all really good ideas Going to try and work on it this weekend Luckily I have an identical good running car, next to it, to swap parts Thanks, will keep you posted. Sent from my iPhone using H.A.M.B.
Want to fill you in on how I fixed the Stovebolt Ramblur came over today and we put our heads together. After rechecking a few basic things like compression and dwell we swapped the carburetor because of a possible faulty Excelerator pump. Brought the motor up to top dead center and put some marks on the flywheel and pointer. Using a separate 12 V battery I checked the ignition timing and found it to be about 4° retarded. The book calls for 2° after top dead center We had to loosen the clamp on the distributor and move it around we came up with 4° before top dead center. That really seem to put the icing on the cake. We went on a test drive and what a difference. I'm going to call this problem fixed. Seriously thinking about just leaving the carburetor where it's at the cars going up for sale so going to leave it alone. But I may bump up the timing on the blue car I think that will live in its performance up a little bit. I did not hear any spark knock so I believe the timing should be fine where it's at JT Sent from my iPhone using The H.A.M.B. mobile app
As a matter of fact..this sedan is available, should anyone be interested. Fully sorted, gorgeous new interior, 3 spd, drive anywhere. Over $15k invested. Reasonable offers considered A full description can be had by contacting me. Sent from my iPhone using The H.A.M.B. mobile app
The Jalopy Journal
