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Old 03-13-2009, 11:36 PM
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thoughts on initial timing?

i have a vortec motor i've built.
9.8-1 compression
.502/.510 roller 08-423-8
i'm using a points style with a IR digital converter through a summit digi box.

how would you go about the initail timing settings? kinda new to this. my first build startup.

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Old 03-14-2009, 01:40 AM
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How about cam duration. Lift doesn't tell us much.... and I'm too lazy to search for that part number
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Old 03-14-2009, 02:55 AM
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Give it 8 degrees BTDC at the balancer. If all's in order, it'll start.

Why points? Not that they're bad or anything, well, they do have their issues, but you don't see many modern builds these days using points.
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Old 03-14-2009, 06:15 AM
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run 15 initial then plug the vacuum advance into a manifold source for another 13 degrees. (28 degrees at idle). get an adjustable vacuum advance canister (accel, summit racing)

then run about another 20 degrees of mechanical advance in the distributor (35 total mechanical advance)

this will make about 48 degrees of timing (35+13) while driving down the highway.

this of course assumes the engine has at least 14 inhg at idle and while driving during lite loads and the cam is big enough to run 9.8:1 cr with pump gas. In your case, I hope the cam has at least 270 degrees of advertised duration, if not then less timing should be used to prevent detonation.

low idle timing is good for emissions and wasting fuel. Plus longer duration cams need more timing than stock. headers glow red with low timing and a bigger cam.
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Old 03-14-2009, 09:07 AM
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i went with a points style for firewall clearance issues. its going to have an accell 2020 electronic distributor convesion kit. there's a small chance i might be able to use a hei.

Intake Duration at 050 inch Lift: 224
Exhaust Duration at 050 inch Lift: 230
Duration at 050 inch Lift: 224 int./230 exh.
Advertised Intake Duration: 276
Advertised Exhaust Duration: 282
Advertised Duration: 276 int./282 exh.
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Old 03-14-2009, 12:10 PM
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To get it started, line up the #1 post with the rotor, then advance it a smidge, like turn the cap 1/4". With that cam and compression it should be able to start anywhere from 4-14 degrees. If you went too far, the starter will kickback. If you didn't go far enough, it will sound like it wants to start, but not quite catch. If you go way too far it will backfire through the carb and sound like someone fired a shotgun right beside your head

Once you get it running and up to temperature (choke off) then you can start tuning things. I'd shoot for 12 initial. Provided that doesn't offer up any detonation at low rpms and doesn't cause starter kickback, there is nothing wrong with it.
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Old 03-26-2009, 04:51 PM
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so i'm going to go the route c10454 suggested but i would like to know what curve you suggest, i ditched the points for the summit billet distributor that is all sorts of adjustable. It comes with an adjustable vacuum advance and four advance bushings (18,21,25,28) with the 21* installed. it also mentions three springs, should i just run the middle on or the stiffest? don't know whats best for me?!
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Old 03-27-2009, 07:31 AM
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run the lightest spring. you want the timing to come in quick as possible. however, if it pings then go up on spring force.
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