20 degrees BTDC is not cutting it!
 

Tried to time the 307 to spec and it does not like it at all! It idles way too fast and struggles to start. 20 degrees seems to be too far advanced. It does like 10 degrees....like the 305 and starts on a dime. Did Olds put "sleeper" 305's in 1983? Maybe a worn timing chain? Anyone have any thoughts? Help sure would be appreciated.


1983 Cutlass Supreme Brougham, 307, Q-Jet.........Bone Stock!

ZOMG - First off how much do you know about timeing a engine? 20 degrees BTDC is not advanced,its retarted 20 degrees. Hard to tell the way you have it written but either way 20 degrees is way too much of either. Try setting your timeing at 5-7 degree's ATDC,not BTDC- that would be the other side of the 0 mark on your timeing gauge. No there is no such thing as a sleeper 305 but yes olds did put chevy 305's cutlasses, If its a chevy or olds timeing is about the same stock depending on features. If you think its a worn timeing chain it should show when your watching your timeing.

this guy is wrong. 20 BTDC IS ADVANCED! BEFORE TOP DEAD CENTER means the spark is hitting BEFORE TOP DEAD CENTER! ATDC is after top dead center meaning the spark is hitting late, or retarded. Anyways to answer your question about the timing, (if im not mistaken) the spec is 20 degrees BTDC at 1500 or 2500 RPM. The label on the fan shroud should tell you exactly what to do, if the label is missing you can get a mitchell or chilton manual and that will help alot. If your timing chain is bad, you will see the timing mark jump around alot when youre timing it (but a misfire will show the same thing). The best way to tell if your timing chain has jumped timing is to take the valve cover off, and bring the No. 1 piston to top dead center EXHAUST. Now watching the valves for that cylinder, turn the crankshaft back and forth. The exhaust valve should be coming up and the intake valve should be pushing down at the same time. This is due to the valve overlap that is ground into every cam. If the valves do this any other time besides at TDC EXHAUST your valve timing is off. You can check for a WORN timing chain by simply removing the distributor cap and watching the rotor as you turn the crankshaft back and forth. The rotor and the crankshaft should have VERY little play. Excessive play is indication of a work timing chain.

You also may have a harmonic balance issue. If the outer ring has spun at all you won't be able to properly time the engine. 20° is correct and I believe the correct RPM is 1100RPM.