SLVRCPE

I have just installed this kit ( heads, cam+lifters and intake manifold ) as well as a new street avenger carb (670 Cfm) . the proplem is my car just flat lays down right off idle to about 2600 RPM. After 2600 RPM the car pushes you firmly into the seatback and is roaring trill about 6000 Rpm. A side not the car seams to have a slight miss under light throttle , as soon as you stand on it though the miss is gone. Any help here will save me from going bald.
also the car has 3.08 gears and roughly 2200 Rpm stall speed.

ohh and by the way Holley says this cam is streetable , heh thats true as long as it not a daily driver. .

here is the link to the kit I installed... http://www.holley.com/HiOctn/ProdLin...K/300-503.html

MasterDave

Uh...if you got the Max cam, your engine seems about right for power, although I would think it would not start moving until higher in the rpm range. Split duration cams have a way of fooling the engine to give a little more bottom end. I've got the CC's XE274H in my sb and it it is as far as I would go for streetability. My suggestion would be to stay with an intake duration of no more than 230-232 and exhaust could go more at 236 or so. I had the XE284H (similar to your cam) in mine for a couple weeks and got way too tired of driving a buckin' bronco at anything below 2500 rpm. You have an auto so you do not feel that as much, but your engine does. :chevy

68shark

Ganey's comments would be welcome here....but my guess (if you have the Max. cam) is it is too much cam for stock converter and 3.08 gears. I have the XE262 in my 327 with 3.70 and 4 speed which is fine because you can wind up a 4 speed and my rear gears help. Your cam has even more lift and thus performs best at higher rpm's. You probably want to build power more between idle and 3000. Ideally, you would probably want a cam like the XE256 (or similar from Holley/Crane) which build torque lower down to take advantage of your stock auto/3.08 gear combo. Changing converter/rear gears may be an option also.

SLVRCPE

I will most likely go to 3.90 gears and 3000 stall. Do you think this combo will work?

gkull

What pistons etc do you have? You really want to end up with 10.5 to make the cam work.

ping at light throttle cruise is to much advance and normally caused by vacuum advance. so if you have a adjustable vac advance turn it down 2-4 degrees and retest. You also need to run 92 or so octane.

I don't know anything about your moddle of carb but bigger shots of gas from the squirter can cure off idle to WOT bog.

MasterDave

Well, yes that gear combo will be better for your engine as it is now, but I thought you wanted to drive it on the street. Very user unfriendly with a 3K stall. One of my friends has stall like this and at freeway speeds he still isn't locked up!! Lotsa mashing on the throttle just to get it moving in traffic, and you WILL overheat your trans fluid. A high quality oil cooler is a must. Just lighten up on the cam a little and you will get it to work better, that is unless you want to be a light to light to gas station wonder. :)

SLVRCPE

the car is just a weekend driver and when I feel the need for speed , I think I will go with the 3.90 gears and see if this helps without going higher on the stall speed. If I still have the same problem I will probably install the 3k stall. whitch I think will be easier than changing the cam.

nunus79

That SystemMax cam uses anti pump-up lifters. Did you adjust your valves to zero lash? Best to adjust them with the engine running method.

SLVRCPE

I adjusted the valves when I installed the heads, went to 0 lash ( pushrod just lighty stop spining) and then 1/2 turn more.

here is what bothers me , the low end power is nonexisting, after 2600 rpm the engine is out of control , I mean it just roars to life . its like night and day performance wise.

nunus79

[QUOTE]I adjusted the valves when I installed the heads, went to 0 lash ( pushrod just lighty stop spining) and then 1/2 turn more. QUOTE]

The anti pump lifters are real sensitive to adjustment. The 1/2 turn more is probably causing you idle & vacuum problems which in turn will affect your bottom end performance. Anti pump-ups NEED to be adjusted to only zero lash. Back all of them off by 1/2 turn & note the difference.

mountainmotor

The 3.08 gears are what is hurting low end.Thats alot of cam no matter what streetable stall you have with those gears .Put some 3.55's in it and watch it come alive.What compression ratio is your engine?It should be about 10.1 with a cam that is 236@0.50
I edited to say that with 71 degrees of overlap a change in the powervalve supplied in your carb will be needed.To give you an idea of how hot that cam is a Comp HE 268 has 47 degrees of overlap.The Comp Magnum 280 has 62 degrees of overlap.I bet it sounds good!Just put some gears in it and go thump on Big Blocks.


[Modified by mountainmotor, 4:48 AM 11/13/2001]

SLVRCPE

I believe the compression ratio to be around 9.8 - 10-1 I have Forged flat top pistons (4-valve reliefs) and my block was decked to 0 clearance. I am going to install the gears first. I wont be able to afford it for a little while so for now I will just play with the power valve to see if I can get the cruise speed surging or miss out of the car, I will post results.
Thanks for all the help.!

RatRacer

I also recommend the 3.55 gear. The 3.90 will be a pain if you go anywhere near a freeway.

nunus79

For clarification, I'm not suggesting the valve adjustment as a replacement for better gearing. I am saying that misadjusted valves should be corrected first, before you decide on other mods.

I tried but was unsuccessful in finding the recent threads regarding anti pump lifter adjustment. I beleive TRW71, Ganey, Wrencher, & Maurice have experience with these lifters. I know for a FACT that proper valve adjustment really improved Maurice's engine. He runs the Edelbrock RPM package w/stock converter T350 & 3.08. I saw his 60 ft. times improve .1-.2, and heard him squeeling the 275/60s for the first time.

Trw71, Ganey, Wrencher, Maurice, care to ring in?