Sorry to bring up another timing uestion as its been hammered out soo many times.
But I have my Cam card, and wanted to get an idea of what my timing should be. And Ive also heard the, advance till max vacuum, then back off... but with a "bigger cam" this might note ven happen..
Heres my dilema -
I have a non vacuum advance dizzy. MSD 8551. So whatever my base timing is, theres no vacuum advance to add.
My cam is 230/236 duration @ .050 on a 350 with a 108LSA
If I go for the recommended.. 22-26 degrees advance at idle from what Ive seen, dont I need a timing retard box, since im gonna eat my flex plate??
Right now its about 18 degrees, not to mention IT BOUNCES! wtf.. it bounces about 4-6 degrees at idle.. ignition Box, new dizzy, ne plugs, new wires...
Cam Specs -
@ 50 TDC 17* overlap 7* intake opens 10* exhaust opens
BDC 43* intake closes 46* exhaust
And I read this, seems sorta close to mine, but IM running about.. 9.5:1 CR
I agree with that, BUT, a lot of people don't really know their CR.
That being said, I am running 10.3 CR with a XE274 cam on 89 octane. Timing is 37* all in by 2600 rpm + 14* vacuum advance @ 12". I set the timing with the vacuum advance plugged, and shoot for all in by 2500 -2800 rpm. Do this by adjusting the springs. I don't care where the initial timing falls. The springs I use pull in some advance at idle, but this is not a problem. Hook the vacuum can up to the manifold vacuum port, not ported. At idle you will get, in my case, 14* vacuum + what ever your initial + centrifugal (if it is kicking in at idle). If I remember correctly, at 950 rpm idle, the timing light shows about 30*. This is ok. Don't worry about initial timing, no one drives at idle, and once you get into it, vacuum advance goes away.
BTW, running a 383 with aluminum TF heads on 89 octane with no problem.
So what should my base timing really be...? And if its over 20, Im guessing I should have a timing retard box/control for my start ups right?
total timing about.. 34-40? right ( remember I have NO vacuum advance)
ALl in by 2500?
I have a 3000 stall, 3.55 gears, and 26" tall tires...
thanks again for the help tech gurus
Oh, I was thinking I need a vacuum pump/canister, because RIGHT NOW, at 18* timing my vacuum is only 10ish