Max timing?

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Apr 3, 2011 | 05:42 PM

corvettedave383

Thread Starter

Burning Brakes

Joined: Apr 2008

Posts: 825

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From: Glasgow, Scotland

Max timing?

Ive got a sbc 383, aluminium heads, big cam, its fast xfi fuel injected, comp ratio 9.2

whats the approx max wot timing? 36 degrees?

thoughts?

cheers, dave

Apr 3, 2011 | 06:23 PM

Gordonm

Race Director

Joined: Dec 1999

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From: Forked River NJ

32 to 36 degrees depending on your heads. Some of the newer fast burn chambers do not need the 36 degrees and actually lose some power with that much advance.

Apr 3, 2011 | 07:06 PM

corvettedave383

Thread Starter

Burning Brakes

Joined: Apr 2008

Posts: 825

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From: Glasgow, Scotland

Quote:

Originally Posted by Gordonm

32 to 36 degrees depending on your heads. Some of the newer fast burn chambers do not need the 36 degrees and actually lose some power with that much advance.

I have Dart pro 1 platinum alum 215cc heads, peak hp is at 6700 rpm

do these heads have fast burn chambers??

cheers

dave

Apr 3, 2011 | 07:39 PM

gkull

Team Owner

Joined: Apr 1999

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From: Reno Nevada

2024 C3 of the Year Finalist- Modified

Yes, run your motor up to 3500 rpm and check the timing. 32-34 degrees is all you need (with vacuum advance disconnected).

I used a Crane cams adjustable vac advance and limited vacuum advance to 6-8 additional degrees.

Apr 4, 2011 | 01:13 PM

Birdman

Safety Car

Joined: Apr 2008

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From: Charleston SC

Quote:

Originally Posted by gkull

Sorry to beat a dead horse here..

but would I do the same thing for my 327 w/stock heads, block and aftermarket HEI, Intake, Carb, headers?

Apr 4, 2011 | 04:32 PM

LB66383

Drifting

Joined: Dec 2002

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From: Long Beach CA

Birdman........Yes, set the timing at 34 to 36 degrees maximum at 3,000 to 3,200 rpm. That's with the vacuum advance disconnected. Then connect the vacuum advance to manifold vacuum. I'm guessing that, with the HEI, you'll have about 14-16 degrees of initial advance. That isn't all that important, the max advance is the important number.

Apr 4, 2011 | 04:43 PM

gkull

Team Owner

Joined: Apr 1999

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From: Reno Nevada

2024 C3 of the Year Finalist- Modified

The 3500 or even 3800 is to ensure that you have full mechanical advance. Actually yester year iron heads require about 36 -38 degrees max advance.

then you go out and road test to ensure no detonation under WOT (where the vacuum advance is zero) Then also cruising on a level freeway where vacuum is max and so it vac advance.

You have to hook you vacuum advance to the Ported carb port so it ads very little advance with closed throttle blades

Apr 4, 2011 | 06:12 PM

corvettedave383

Thread Starter

Burning Brakes

Joined: Apr 2008

Posts: 825

Likes: 40

From: Glasgow, Scotland

Quote:

Originally Posted by gkull

Thanks for info, the fast xfi controls timing, so I just need to check the check the spark table for levels and changing the timing at different points on the map

cheers

dave