Timing question

2745 Views 13 Replies 5 Participants Last post by [email protected], Nov 21, 2012

Cruzin_Flick

Discussion Starter · Oct 14, 2012

SBC running a 4bolt main, Comp cam ( Xtreme energy XR276HR) World Heads Sportsman II 2.100/ 1.625 72cc 23degree angle,Sidemount Hookers, Edelbrock Aluminum intake Performer, Holley 650 cfm, Accel High Performance HEI Distributor.......question is, what is the best timing to run with this set up. I'm currently set at 8 degrees advanced. Seems to run ok but everyone says I should be running at 12 or more advanced. I have a new high torque starter to be installed as it is hard starting when I run it hard for a while. If I run it below 6 degrees the headers glow. Too hot and to late on the timing right?

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TimAT

· #2 · Oct 14, 2012

Not only is the initial timing important, but the total advance is too. AND the rate of advance. IT's all adjustable with a combination of vacuum advance cans, springs and weights.
Lots of ways to get there. Easy way is to send an email to Lars at [email protected] and politely request a copy of his timing paper. Follow his instructions and you get 2 things- 1, an understanding of how it works, and 2, the timing on your car set correctly.

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buster

· #3 · Oct 14, 2012

TimAT said:
Not only is the initial timing important, but the total advance is too. AND the rate of advance. IT's all adjustable with a combination of vacuum advance cans, springs and weights.
Lots of ways to get there. Easy way is to send an email to Lars at [email protected] and politely request a copy of his timing paper. Follow his instructions and you get 2 things- 1, an understanding of how it works, and 2, the timing on your car set correctly.

Agreed, good advice. :thumbsup3:

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Cruzin_Flick

Discussion Starter · #4 · Oct 14, 2012

Thank you, the email is on its way.

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[email protected]

· #5 · Oct 15, 2012 (Edited)

the purpose of advance is to light the fuel/air earlier in the cycle as the rpm goes up....it takes the same amout of time to light at 5,000 rpm as it does at 1000 rpm, so you must light it off earlier to achieve proper burn. a performance chev small block usually needs 10-14 * initial adv , plus 20-22 centrifugal adv in by 2500-3000rpm , for total 34-38* .. and if you use a vacuum advance, you can add 10-12* for it at part throttle, which will give you 44* or more at light throttle, cruising speed .. ...this is based on premium fuel useage......this will vary slightly by cam /head design on any given engine .. if your pipies are glowing, you have late ignition timing or you have an exhaust restriction... I run my 383 stroker with 14* initial, 22* mechanical and 10* vac adv.. we tried various combo on the dyno, this is where it was "HAPPY"...

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TimAT

· #6 · Oct 16, 2012

[email protected] said:
the purpose of advance is to light the fuel/air earlier in the cycle as the rpm goes up....it takes the same amout of time to light at 5,000 rpm as it does at 1000 rpm, so you must light it off earlier to achieve proper burn. a performance chev small block usually needs 10-14 * initial adv , plus 20-22 centrifugal adv in by 2500-3000rpm , for total 34-38* .. and if you use a vacuum advance, you can add 10-12* for it at part throttle, which will give you 44* or more at light throttle, cruising speed .. ...this is based on premium fuel useage......this will vary slightly by cam /head design on any given engine .. if your pipies are glowing, you have late ignition timing or you have an exhaust restriction... I run my 383 stroker with 14* initial, 22* mechanical and 10* vac adv.. we tried various combo on the dyno, this is where it was "HAPPY"...

THose same numbers apply to the big blocks too. I'm running a total of 36*.

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[email protected]

· #7 · Oct 17, 2012

TimAT said:
THose same numbers apply to the big blocks too. I'm running a total of 36*.

great minds think alike, eh?

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TimAT

· #8 · Oct 17, 2012

[email protected] said:
great minds think alike, eh?

I don't know if it's the great minds or just the stuff that we have discovered (by trial and error) that works..

My normal trial and error:
:1sm258fight:

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[email protected]

· #9 · Oct 17, 2012

LOL!!! lots and lots of ERROR!! I think I ve invented a few new words on occasion, when things go haywire..:z1-2:

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Cruzin_Flick

Discussion Starter · #10 · Oct 19, 2012

Thank you all very much for the info. Received an email from Lars........Wow! He really knows the issue of timing!! Very impressive!!

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TimAT

· #11 · Oct 19, 2012

Hehe..

Lars is a retired GM Training Center instructor. Back in the days GM had training centers. Now it's all computer based. I went thru a bunch of GM's schools when I worked at dealers.

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[email protected]

· #12 · Oct 21, 2012 (Edited)

I ve read a bunch of Lars stuff, been a few years.... very smart guy , knows his stuff ..small blocks are relatively easy to set up timing curve

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nevr2ol

· #13 · Nov 21, 2012

timing light

Is thereany particular type of timing light Lars prefers? Or any onther kind for that matter..

Thanks.
Bill

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[email protected]

· #14 · Nov 21, 2012

preferably one that works! I m still using mine that I bought at Sears 4 decades ago

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