timing advance question

[will scratch]

what are the advantages or dis advantages for locking out mechanical advance. how much advance is introduced into the engine by using it? any insight would be helpful. thanks

[fiddy9apache]

if your running alot of timing it will be hard to start in some cases with the advance unhooked.

[cableguy0]

Locking out the mechanical advance will kill your performance and mileage. locking out a distributor is typically only done on race engine which have another form of ignition advance electronically. The amount of timing provided by the mechanical advance depends on the distributor and the springs and weights used. Generally on a sbc you want 36-38 degrees total timing(initial plus mechanical. Then the vacuum advance will come in on top of that. usually sbc's like between 12-18 degrees of initial initial timing. Mechanical will provide the rest to get to the 36-38 range. Theres a good article at the top of the engine and drivetrain forum on how to properly set the mechanical advance and curve the distributor.

[will scratch]

thanks that really helps. I'll check out the other post also.

[Marv D]

Can only 'ditto' the cableguy's comments. Locking out the advance is fine if your at the track, launching the truck above 4000rpm so that the only time the motor sees anything below 3600-3800 is ideling around the pits. What it does is give you a rock solid baseline of whre your timing is (no revving it to the moon to see where the advance tops out) You set it at 37° at idle and (assuming no cam walk) it's at 37° everywhere in the rpm range. It's not a street thing by any means. Locking out the advance is only practicle when the operating range of the motor would be ABOVE any advance function.

Hey ya know one more thing it will do for you,, it test the strength of your starter and flexplate. I've seen more than one starter break the nose off on a high compression engine that had the advance locked out. If you don't have a start retard,, it's murder on starters.

[cableguy0]

IN order to properly lock out the advance requires a good bit of money in electronics to make it right and function properly. Without a retard box you wont get an engine to start with 36 degrees of timing at idle.It would likely eat starters and flywheels for lunch.But either way its a race only thing and definately not streetable.

[team39763]

What is a decent amount of initial timing to save the starter? I have 32* total and I have it set to start with 15*(or 20*) and ramps up to 32* by 1100rpms...idles around 750-900rpms with 20*. Mine is race-only.

[cableguy0]

first off all 32 total isnt enough timing. without knowing what the engine is its impossible to tell you where it should be but regardless 32 is too low.

[team39763]

I'm just wondering what amount of timing is easy on the starter? I may have worded it wrong before. Should I have the timing retarded to 20* or 15* or run full advance from starting rpms on up(just for starting)?

[cableguy0]

what is your setup? need a bunch more info to fully answer that question. What engine? cam? heads? ignition system?

[team39763]

LQ4, 22X cam, 823 heads, MSD ignition controller. It has less than stock compression. MSD box needs to see 300rpms before it turns on, so I started the timing off at 18 from that point then ramps up to 20 once at idle rpms(750-900). From 1100rpm+ it's 32*. I was just wondering if 18* is easy on the starter or do I need more?

[cableguy0]

If its not struggling to start your in good shape. You will know 100% for sure if you have too much timing while cranking. The starter will struggle or even kick back.