How do I set the timing on a 350/290 HP engine without vacuum advance?

Question

I have a 350/290HP engine in an 83' C10 Silverado, How many degrees BTDC should I set it without vacuum advance to end up with a total of 34 +/- 2 degrees BTDC with vacuum advance, i.e.(6, 8, 10, etc.)??? Please help me!

Answer 1

best way is to fully warm up the engine, then raise the rpm up to 3000 rpm, set total advance to 36*BTDC, leave vacuum hose on distributor if equppied and you should end up around 6*BTDC @ 650 rpm or so
But, most small blocks like a total advance of no more than 42*BTDC @ 3200 rpm on a normally aspirated engine and less when running superchargers or turbos etc etc

Answer 2

You want to set ignition timing with a "vacuum gauge"? Well, that is really a secondary way of checking timing and engine status ( primarily valve-train issues). So, if you have a radical cam and you are hooked up to manifold vacuum you will see @ 15 in. which will "lope" along ( rhythmically bump up to @ 15.5 inches ) with your cam. Milder cams will read a steady number between 15 to 22 inches. You might be thinking of a sluggish indication that wanders between 14 and 15 inches which indicates excessively retarded ignition timing. Hope that helps!

Answer 3

Your vehicle manual should tell you the base timing. But if you don't have one on hand do this......adjust the timng at 28 degrees. Next connect the vacuum advance and see if it adjusts six degrees if not annotate the difference. Lets say you adjust it at 28 degrees and once the connect the vacuum advance it adjust to 32...this means the difference is four degrees. This time adjust base timing (without vacuum) at 30 degree.....catching on. Good luck.