Just finished my L05 small Block Vortec upgrade with harder springs, Howards camshaft 183215-14 and 1.6 ratio roller tip rockers.

Camshaft: 270/278 495"/500" 114° Hyd. Roller.

Any ignition timing recommendations?

 

Assuming factory style HEI distributor with 22* mechanical advance. I would start out around 10* initial timing for 32* total without vacuum. Leave the heaviest springs in the advance mechanism and hook the vacuum canister to manifold vacuum and limit the vacuum advance to about 10* for initial tuning. I feel you will find your peak HP in the 30-34* total advance range. Depending on gear ratio and stall speed you might also be able to bring your advance curve substantially quicker by substituting weaker springs one spring at a time until you find the best acceleration without detonation.

 

Typically, it's recommend
10- to 12-degrees of initial timing when the duration of the camshaft is less than 220-degrees @ 0.050” of valve lift
14- to 16-degrees of initial timing with a camshaft duration of less than 240-degrees @ 0.050”
18- to 20-degrees of initial timing when the camshaft duration is less than 260-degrees @ 0.050” of valve lift.

This only gets you in a ballpark range. A dyno tune is the only way to know exactly where an engine wants it's timing. Changing things like jetting, plug gap etc will not change where the engine wants the timing to be so you always start a tune with timing.

Once the base (initial) timing is set, you need to find out where the engine like the total timing. You don't adjust the base timing to increase or decrease the total timing. That's where a distributor recurve comes in or on EFI vehicles, the ECM gets reprogrammed.

 

Thanks.
Very informative answers from you guys, as always!