Chevy Nova Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
70 Posts
Discussion Starter #1
Hello,
I am running a 355ci, Vortec heads, balanced, 10 to 1 compression rpm intake, 600 cfm carb, auto tranny and a gm hei distributor.My question is what kind of timing set up is working good for every one who has this cam. I have tried 8 degrees inital but it seems I'm leaving power behind and the motor wants to diesel. I have also tried 12 degrees but my motor likes to build too much temp. Any suggestion are appreciated and would be helpful.
 

·
Registered
Joined
·
234 Posts
Total timing is what you really need to focus on, rather than just initial. I see most folks with Vortec heads say their engines like 34-ish degrees total. I'd try 10 or 11 degrees initial, but make sure it's bringing in enough on the advance to make 34 total. Bottom line is set it where the engine is happiest :)
 

·
Registered
Joined
·
70 Posts
Discussion Starter #3
That is what I have been reading, I just have been reading about guys doing like 16 or 18 inital making their mechanic adv less and putting an adjustiable vac can and talking like it has worked miracles
 

·
Registered
Joined
·
234 Posts
Well, if it's still building too much heat at 12 degrees, then that tells me it's still retarded too much. Maybe the 16 degrees is closer to correct for initial, but I still don't think you should do more than 34-36 total.
 

·
Registered
Joined
·
337 Posts
Virtually the same setup here (have 650cfm carb tho). Same deiseling at 8 degrees. Its at 12 degrees now and I run around 200 degree temp with the sensor in the drivers side head.

Seems to just run a little hot. What plugs are you using?
 

·
Registered
Joined
·
3,649 Posts
Vortec 355, 268xe, 9.7:1, 650DP here. MSD Pro-billet distributor, R44LTS plugs gapped at .045

I run 16 initial, 18 mechanical, 34 total. All in at around 2750. I run premium gas- what's in your tank?

I tried running less initial but it seemed to be a bit more sluggish.

I seem to remember the HEIs having a lot of mechanical advance built in or something like that.

Here's my thread on the topic:

http://www.stevesnovasite.com/forums/showthread.php?t=197709&highlight=vortec+curve
 

·
Registered
Joined
·
364 Posts
I'm running a similar setup in my 74 Omega except with the XE274 cam. 355, Vortec Heads, Edelbrock EPS Intake, Holley 650 DP, MSD Streetfire Distributor. Plugs gapped at 45.

Rev it up to 2500 and set my total timing to 34 with no vacuum advance, just mechanical.

I've also ran and timed it and then hooked up vacuum advance and notice no difference in performance.

I find my 355 combo runs around 200 too ...

I ran a 406 with that cam in my Nova until this past spring .... I like it, was a good street motor! with 14 degrees of timing, gave me about 34 total too.

I've gone with just mechanical advances now on both vehicles .... seems both of them run fine ....
 

·
Registered
Joined
·
70 Posts
Discussion Starter #9
Wildbillyt great thread it answered most of my questions. How does your motor run now?



I set my timing to 16 inital it runs much better, no overheating and more power but still not quite there yet. To answer the question above 91 octane. Also my cam is four degrees retarded. Will that Affect my timing curve?
 

·
Registered
Joined
·
3,649 Posts
Wildbillyt great thread it answered most of my questions. How does your motor run now?



I set my timing to 16 inital it runs much better, no overheating and more power but still not quite there yet. To answer the question above 91 octane. Also my cam is four degrees retarded. Will that Affect my timing curve?
IMO my car runs very well now. I could probably get a little more out of it but I'd need a dyno and wideband to do so. My one regret is running a 2116 performer vs a 7516 air gap. My 4.11s keep the RPMs up so it's a waste.

It starts up on the first crank, pulls strong, no pinging, etc.

I'll defer the cam degree question to somebody with more knowledge. Don't want to speculate and steer you wrong. I installed it according to Comp's guidance.
 

·
Premium Member
Joined
·
1,304 Posts
Comp Cams xe268H. Timing Curve

Hey Now 4 Degrees retarded... This helps top end power and RPM's, BUT DESTROYS low end/out of the hole grunt...I suggest install the cam to specs on cam card. Respectfully, "Bill's" II (if car is automatic, get higher stall speed convertor; 3400 rpm's)
 
1 - 12 of 12 Posts
Top