hey guys.. thought id drop in and get some feedback. Recently finished a rebuild on my 350 camaro - and although the power is nice, its nothing near what i expected. Its my first build of a chevy specifically, and the mods ive put in dont really seem to be playing nice.


sorry for the lengthy post - but i thought id divulge as much info as i can to avoid irrelevant suggestions!


Stall
Only element yet to be upgraded is the stall - mine is stock, and ill prob go for 2400 about. i hear this will make a big diff. This is a daily driver with long distance trips in mind now and then, but also a sporty city toy.

Timing:
here it gets a little confusing, but i have determined i have a 10 degree vac adv (AR22), my dizzy does no more than 25 mech, and my weights / springs are good and hei runs gr8. I noticed my vac uses ALL the vac on idle, it literally jumps from 12-22 when i connect adv.. leaving nothing for part throttle cruise.. can i move this window or will i have to get an adjustable canister? i have 12 innitial,

My cam is a lunati barebones 102101:
Duration 280/290, Lift .443/.465

Qjet (on a professional products Air gap intake)
Iv recalibrated the qjet, i was running a 6hg pri spring but switched to an 8hg - tested it at idle and the pri rods are still pulled all the way down - so there is def alot of vacuum (however i seem to have noticed a slight drop in accel) - surely the stiffer spring will lift the rods out earlier? perhaps too early?.

secondaries
I noticed my secs arent opening, the can just isnt releasing no matter how hard i mash it on the road, at the point where the secs must open it bogs/dies - i have to feather it to maintain speed. My throttle cable is fully adjusted - ie giving max wot travel on floor pedal.

71 jets and 42 rods.

At the mo im getting about 18mpg highway driving quite spirited, and the car sounds good - but rear wheel just isnt where i thought.



Specs:
77 350 two bolt 40 over
flat tops
stock crank/rods
vortec heads - stock
2 dual 2 1/4 (no cat)
1 5/8 long tube headers with 20" 3" collectors - no cross over
professional products air gap intake
spreadbore/squarebore adapter for qjet
295/60/15 rear
3.42 open
200-4r

 

Without vac advance you should be around 36 degrees at 3krpm.

 

thing is my car doesnt have a tach will see if i can hook something up this week..

 

Have a friend rev the engine until it stops advancing. See where it is and adjust it accordingly. You want it to stop advancing after it hit 34-36 degrees all mechanical

 

ill take some timing specs again 2moro and write them down and post em here. Im not sure if the timing can make such a big difference? if its coming in to soon - would that take power away drastically? im leaning more toward the stall being stock.. im not a fundi on this.. very close specs to the GM crate 350 HO actually ~

 

Timing makes a HUGE difference

 

id like to take some vac readings as well as im sure ill need to know what im pulling when - in case my vac is way out of spec. I have alot of idle vac thats for sure.. my qjet pulled the 8hg spring right down instantly..

 

[QUOTE=fstarocka;5554792]
. I noticed my vac uses ALL the vac on idle
[\Quote]
Your carb should have a timed vacuum port on it for this reason.

 

u mean ported vac instead of manifold? ive read manifold is best for NA non egr cars //

[QUOTE=Chad85T/A;5555031]

 

Yes. Some people like manifold vac. I've always had a problem w it having too much timing at idle w manifold vac.

 

well ive heard ported shouldnt apply vac @ idle - but most of the ports on mine do afaik. the vac is only really for cruising not true? will tweaking the timing have such a big effect on pwr? ill get the numbers 2moro and write em down.. without a tach its gonna be tricky tho.. all i can see is what total mech adv is, and vac.. but not where / rpm etc.

 

Just make sure your mech advance maxes at 32-34 degrees because your using vortec heads. If your only at 25 now you could be missing 10-20% HP

 

You really need a tach. My timing light tells the RPMs on it which IMO is really handy. The way I go about timing is w ported vac I can get less timing at idle and can bring more timing in as the RPMs raise, where if I bring all the vac in at idle I seem th have detonation and can't actually run as much timing overall.

 

I think you have to select a vac canister that comes in just lower than idle vac, about 2 inches i believe - not sure if prev builder matched can to cam, but looks like im gonna have to.

I think the fully adjustable vac cans (not just amount but when) is my best option - that way i can not only limit it but set it up for a given window of vac..

this make sense? comp cams i was looking at came with a cam for mech limiting, is the vac adjustable for rate AND at what vac on the fully adjustable ones?