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Discussion Starter #1
Hey fellow Camaro Lovers!

I have a few questions about my engine timing, but first I'll explain what I have.

I have a 350 ci block bored .060 over, holley aluminum 202/160 heads, 9.5:1 compression, lunati cam(hydraulic, lift: .477 in and .507 exit), advanced crank cog 4 deg, holley street avenger 670 cfm carb w/ vacuum secondary, aluminum edelbrock rpm air gap intake, holley billet magnetic pickup distributor, holley annihilator electronic ignition system, and harlem sharp roller rockers. This is a 4 spd car.

My question deals with timing. I have heard arguments for both ported and full manifold vacuum for the vacuum advance. I'd like to know which is best for my application. Also, any help with centrifugal advance curving and curving for the vacuum advance will be appreciated.

Thanks!
 

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Scott,

I have read that article previously as well as John's Advance 101 post and thread but thank you.

All the arguments I've heard for full manifold were with HEI and points distributors. That"s why I'm not sure given I have a magnetic pickup dist. with electronic ignition. :confused:
 

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I have heard arguments for both ported and full manifold vacuum for the vacuum advance
.
There are no "arguments" a non egr / pollution engine has manifold vaccuum on the VA, lots of degrees in the VA and not so many in the cent, usually all in at quite high rpms.
A non EGR pre early 70s has manifold vaccuum, all in at idle best temperasry mixture settings at idle rpms, no many degrees in the VA 7 to 7 and generally over 22 degs in the cent usually all in far lower than a ported dizzy.

All the arguments I've heard for full manifold were with HEI and points distributors.
yes sort of... HEIs and RGR pollution addons all happened after the 1st international oil crisis in the early 70s..some of use where around then...
The HEI was introduced not as an 'upgrade' but so very lean cruise mixtures at high advance numbers could be ignited with the bigger energied spark which the pionts could not do as well.
So HEI lean mixtures, EGR big advance cruise curve all happened at the same time, as a result 99% of all HEIs aftermarket nor otherwise out of the box are set up for EGR engines, which happens to be a ported vaccuum.
It is not difficult to put more degree in the cent, reduce the degs in the VA and drop the top Vacuum spec of the VA down.
All described several times in older posts
 

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Discussion Starter #6
Thanks everyone for the quick responses. I've read pretty much every timing post on this site, but I'm still not really sure about what to do for this engine. So, just to make sure I've got this strait: for my application, which is a non-EGR car, I need to use full manifold vac for the Vac Adv, I need to run full vac advance at idle with about 22-24 deg advance at idle, and approx. 34-36 total advance above 3000 rpm.

My question is: for my engine what should I use for my initial timing, at what vacuum reading should the VA fully deploy, and how mmany degrees should the VA pull at full deployment?

Also this may give some insight into the problem: When I first ran the engine and drove the car, the engine never really wanted to start, engine kicked back and the headers glowed. To fix the glowing problem, I adjusted the mixture needles more to more lean and retarded the timing but then it wouldn't idle below 1200 rpm and barely under 1500. The engine ran like S*** on the road, ESPECIALLY when I gave it any gas. When I advanced the timing back and brought the mixture back up, the headers glowed again, but it would idle at 1100-1200 and ran worlds better on the highway. The problem then was it oscillated between 1000 and 1200 rpm at idle and would not die when I turned the key off. Is this characteristic of anything y'all have experienced?

I am sorry I've asked so many questions, but I am relatively new at this as I am only 18.
 

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My question is: for my engine what should I use for my initial timing, at what vacuum reading should the VA fully deploy, and how mmany degrees should the VA pull at full deployment?
I have described many times how to dial a dizzie in and how to 'machine' file counterweight to adjust the cent timing ands how to change the start and finish pionts + number degrees in the the VA

AND to dial in, establish your tuning specs, u need the AFR in ball park 1st..
Ball park specs initial between about 8 and 14
Around 22 / 24 degs in the cent all in around the 34/36 @around 3000 3200 rpms Then retard to dial in.
VA all in somewhere between 7 and 14" depending on your engine charactorists...and between 7 and 10 degs

All thew above then get juggled into a working dizzie once the engine specs (dialing in) are established for idle advance, total advance, and keeping below 40/42 degrees onless dialing in lean cruise with a knock sensor... yes a knock sensor NOT your ear.
 
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