454 Timing

[custodian]

I tried to search for an answer but no luck. I have an 86 C30 with a 454, manual trans, Quadrajet with all the smog removed. The stock timing is 4 degrees before top dead center. Can the timing be set higher without any issues?

 

[Ricko1966]

More timing does not necessarily mean more horsepower,torque or mpg. I start timing low and bump it in 2 degree increments for highest trap speed in a measured distance around an 1/8 mile. Pick 2 landmarks,Take off, when you pass your 2nd land mark check your mph. Not time,mph. Highest trap speed with lowest timing setting is about as good as you are going to get. Here's the thing a lot of people don't think about,the earlier you light the flame the more crank degrees the engine is doing negative work,fighting the expanding combustion until it passes TDC. So lowest timing,highest mph is most efficient.

 

[Vbb199]

The lower the timing is BTDC, the greater the efficiency of the pump.

A motor operating at 40° up top isnt as great of a "air mover" as one that uses 20° up top. Could he due to restrictions, bad cam selection, valve sizing, reversion, many things.

That said, spark numbers mean nothing, ya gotta find whats best for it like Rick said

 

[Grit dog]

I tried to search for an answer but no luck. I have an 86 C30 with a 454, manual trans, Quadrajet with all the smog removed. The stock timing is 4 degrees before top dead center. Can the timing be set higher without any issues?

Have you actually checked the timing? Not sure what you’re looking for here. Like the guys above said, the right timing is the right timing and that differs based on a dozen different things.
Base timing is one thing. Total advance and timing curve is completely different and also or even more responsible for the way an engine performs imo. But to that end, the condition of the engine and everything else that makes it run are equally or more responsible for performance or lack thereof than kicking a couple more degrees of timing in. JMO. Not a distributor tuning expert but still messing around with 50 year old cars 35 years later since I first started driving them.
Maybe some context to your question would help answer it. Is there a problem you’re trying to correct? Or just a hypothetical question?

 

[custodian]

Have you actually checked the timing? Not sure what you’re looking for here. Like the guys above said, the right timing is the right timing and that differs based on a dozen different things.
Base timing is one thing. Total advance and timing curve is completely different and also or even more responsible for the way an engine performs imo. But to that end, the condition of the engine and everything else that makes it run are equally or more responsible for performance or lack thereof than kicking a couple more degrees of timing in. JMO. Not a distributor tuning expert but still messing around with 50 year old cars 35 years later since I first started driving them.
Maybe some context to your question would help answer it. Is there a problem you’re trying to correct? Or just a hypothetical question?

Nothing wrong with the timing, not looking to gain horse power or torque, just seeing if changing it would help or hinder. I've got it at 4 Degrees BTDC.

 

[Grit dog]

Nothing wrong with the timing, not looking to gain horse power or torque, just seeing if changing it would help or hinder. I've got it at 4 Degrees BTDC.

The good news is it’s easy to adjust and see if there’s anything left on the table.
But my theory with non hi performance engines. Especially old ones with old parts is if it runs good, starts easy, doesn’t backfire out either end, doesn’t ping and doesn’t diesel then it’s just right.

 

[rich weyand]

Everything you ever wanted to know about ignition timing.

 

[rich weyand]

Everything you ever wanted to know about ignition timing.

 

[malibuman402]

I would suggest 8-12 degrees BTDC with the vacume advance disconnected. then reconnect and take it for a ride.