Rebuilt the carb - thought it was a fuel issue ! But this car has no power - 0-40 in like 35-40 seconds ! It’s a dog and slow and dangerous on today’s roads! So what can I do to diagnose when this motor is so weak and no power at take off or normal driving ! Thanks much !
Back to basics. Warm it up, then do a compression check. Run the valves, if applicable. Check ignition dwell, timing, advance and spark. Check fuel delivery. Check exhaust for plugging, which is common on old revived cars. Make sure brakes aren't dragging. Check drivetrain for excess drag, too. https://www.teambuick.com/reference/buick_8_engine_specs.php
Try the factory service manual tune-up procedures. I was ready to swap out my 248 until I tuned it up. It's not the fastest thing on the road, but there's plenty of torque there. Do you have the auto or manual trans? Link to tune up procedure: https://www.hometownbuick.com/1952-buick-engine-tune-trouble-diagnosis/
What transmission do you have? Those old Dynaflow transmissions were awful if taking off in drive. The only thing I could ever find to get 'em going was to take off in Low and wind it up then shift to drive, which is not recommended by Buick. The instructions state that low range is for holding back on steep hills. The standard transmission is much better but still pretty asthmatic. How many miles are on your engine? If the compression is low it will be a big problem getting any performance out of it. If a proper tune-up doesn't help and compression is good, I don't know what to tell you. More info would help with diagnosis.
Yep, these guys have steered you right. My '53 Special is slow, but more like 0-60 in 15 seconds slow.
If the engine holds a fairly steady idle, check the manifold vacuum in neutral. You'll hopefully see a steady 16" to 19" of vacuum. Also drive it a bit with the vacuum gauge attached and see how it responds. Under hard acceleration it should drop the vacuum to near 0".
A friend of mine had a car that had low power and was over heating, he did everything to that engine but to no avail. Turns out the brakes were dragging, Sometimes it pays to think outside the box. Another story about thinking out of the box, my neighbor brought me his car and told me the transmission swas slipping and would not shift out of low. I tore it down and fount nothing wrong so I put it back togeather and drove it, still a problem. took the exhaust loose at the header pipe and the car sprung to life, muffler was plugged up. Just jotting down some of the odd stuiff this thread reminded me of.
Unless it has been removed, check the exhaust damper valve at the outlet of the manifold. A lot of times it is frozen in a partially or mostly closed position. Its purpose is for faster intake heating for fuel atomization and is supposed to open fully as it warms.
The exhaust heat riser flapper is stuck in UNKNOWN position - I’m gonna pop off the carb and try to see where that’s at - if closed would that restrict power -
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