Spark for H/C cars

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Apr 10, 2006 | 08:23 AM

jub jub

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From: Warner Robins, GA

Spark for H/C cars

Hey guys (and gals). I have my fueling pretty much dialed in but I was wondering, what do you guys do about your spark tables? I mean, is there any rule of thumb or a spread sheet that can help me figure out how to optimize the spark table for my car.

I have the spark set-up on mine so that at WOT I'm at 28* which I believe is where my engine made the most HP on the dyno. But I'm wanting to optimize the other areas such as cruise, part throttle, etc. I've added 3* to all other areas on the spark map and I'm not getting any KR but I'm not so sure that is a wise thing to do.

How does GM do it when plotting a spark map for a particular cam? I'm sure there is a lot of math involved and if I have to go that route it's fine by me.

Any and all help much appreciated.

Apr 10, 2006 | 09:37 AM

GuitsBoy

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From: Long Island, NY

I started off with all 99 f-body timing tables since theyre more agressive than later models. Ive done a bit of tweaking since then minly right off idle.

Apr 10, 2006 | 11:55 AM

jub jub

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From: Warner Robins, GA

Thanks GuitsBoy. This must still be a grey area or it's been beat to death.

Apr 10, 2006 | 11:57 AM

silverTA2002

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From: Bradenton, FL

I'm only running about 24* at WOT. That's the most I can have without KR.

But, with my .030 gasket, I'm at about 11.3:1 compression. From what I hear, that's about right.

Apr 10, 2006 | 12:20 PM

MeentSS02

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From: Dayton, OH

Quote:

Originally Posted by jub jub

Thanks GuitsBoy. This must still be a grey area or it's been beat to death.

I think it is more the former than the latter...timing is kinda weird like that. The only way to tell is on the dyno, and I just don't want to pay for dyno time to screw with my timing.

Apr 10, 2006 | 12:54 PM

jub jub

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From: Warner Robins, GA

I'm using the old rule of thumb "Advance it until it knocks and then back off a few degrees". I'm not real comfortable with this but it's all I can do without spending all day on a dyno.

I just thought I could use a spread sheet or something to help calculate proper spark at various loads and RPMs.

Apr 10, 2006 | 09:32 PM

VTC_WS6

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From: Austin, Tx

Quote:

Originally Posted by jub jub

Don't put too much stock in that. An engine only needs so much advance to achive MBT, you could advance it more without incurring trace knock but make absolutley nothing in terms of power, infact all you'll serve to do is increase the effective compression and heat in the chamber with nothing to show for it.

FWIW, my T/A made it's peak power at 24* @ WOT on a dyno, stock timing is 28*.

Food for thought.

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