I have a 57 Coupe De Ville with the stock 365 caddy engine. The heads were recently refurbished and installed and now I'm trying to get the timing in order. This is what I encounter. Per the instructions in the manual, I unplug the vacuum from the carb that goes to the distributor and plug that whole with some tape. I then set the timing at 5 degrees retard and clamp down the distributor. When I put the vacuum from the carb back on the distributor, the timing goes to about 25 degrees advanced and I haven't touched the distributor. Is there a carb vacuum leak or some other problem or is this perfectly normal? Comments would be appreciated.
Is your vacuum line connected to the correct port on your carb? If it is sounds like the vacuum advance may be shot,you'll need to check that out.
Sounds like things may be normal. Distributor specs for your Cadillac are as follows: Vacuum: 0 advance (engine) at 8" mercury 3.0-10.5 advance at 11" 10.5-22.5 advance at 13" 16-25.5 advance at 14" 21-25.5 advance at 15" and for reference, Centrifugal: 0.5-3.5 advance (engine) at 800 RPM 21- 25 advance at 4000 RPM ***uming you are about sea level and the engine is in good shape you should have about 14-16" vacuum at idle which would mean the timing should advance anywhere from 16 to 25 degrees when you hook up the advance. The only way to check for sure is get the distributor on a machine but you can do a quick sanity check: with the timing light and vacuum advance hooked up, while idling blip the throttle, you should get a momentary retard in timing. And for what it is worth, static timing should be 5 advance, not retard, which is the A line on the balancer. The C line is TDC.
Gents I may have the A and C line mixed up. When I look at the balancer from the drivers side, I ***umed that the bottom line was C and the top one is A. Please correct me if I'm wrong.
You are correct in setting your timing a little retarded, a note in the book says to do that when you can't get fuel with a 97 octane rating or better to prevent detonation. Remember you are dealing with a 10 to 1 CR in an engine made to run on leaded gas.
I have the same picture in my book. That's what confused me....My timing pointer is on the drivers side and yes, I did note the special comment in the manual. Having said that, I think I used the A line to set my timing rather than the C line since I was looking at it from the drivers side. I'll have to redo it and see what happens.
I've been told to check the timing with a vacuum guage. Can anyone give me the proceedure.... Thank you.
It involves advancing the timing with the engine running until you get the highest vacuum reading then retarding until the vacuum gage needle starts to fall, it's kind of like timing by ear if you were hard of hearing. It will do in a pinch but I don't recommend it. Better to find TDC #1 cylinder and check your timing marks if you don't trust them.
Thanks Mike. I set the timing again. My timing mark needle is on the drivers side. When I see the two marks, I set the timing on the lower of the two. Technically, using the picture, that would be the A line. When I switched to the top line when looking from the drivers side, the engine ran very poorly and rough and carb response was poor. So, I readjusted back to the bottom line and it runs well. I don't think that's what the manual had in mind, but that's where I'm at.
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