Ok...so in my search for horsepower, I cannot seem to find the missing link. I know that my motor should make more hp than it is. My time slips show that

I am cutting a 1.70 60' time, and a 13.20 in the quarter at 100 mph consistantly.

Engine:

383 sbc
9.7:1 cr
288 xr comp cam w/1.6 rockers == .555/.576 i/e 236/242 @.050
AFR 195 heads upgraded springs and studs
Holley MPFI Commander 950 ECU
TKO trans and 9" with 3.5 gears
1-3/4 Super comps
2-1/2 mandrel flowmaster kit

I feel i should be cuttin 11.80's on this motor, and am off by a full second and a half.

My question is this....

What is the max load that a lifter can handle before it goes flat?

I am beginning to think that my valve noise is not so much from a large lift cam, but might be attributed to the lifters going flat. Is this possible? My tune is close enough, well not worth a second and a half off if you know what i mean. The car drives fine, but am down on power. Any Ideas

thanks

chuck fry

Thats right where that car should be. you are not down on power at all it should rev more than about 5500 at the most. There shouldnt be any nioises from the valvetrain.

I think it's slower than it should be. I had a very similar combo in a full-weight 72 Camaro with a/c, auto trans and crappy 1.95 60's and it ran 12.20's at 113.

Jody

I agree jody, and am trying to find the issue. I have valvetrain noise when the car warms up, sounds almost like a solid roller. I was wondering if this was due to the high lift, or if the lifters could possibly be going flat. The lifter thing would explain why my car is not pulling on the high end, but dont know if its possible. I am running the stock vortec block lifters, and am running a moderately high lift cam in the 550-570 range. I should make almost 500 hp, but wont put it on a dyno till i find the problem. Is the lifter issue possible. I have checked all rocker arms, and they are set to zero lash, as they should be. I adjusted them when i built the motor with the intake off the car, looking at the pushrod to lifter clearance as i put it together. So there is no way they could be off or back off due to the poly locks. Any input would be appreciated.

Thanks

chuck

well, I always say this, and a lot of people do it and make a big mess, and some fix thier problem.

Run the lifters once quick with the motor running. Make sure you're at "no clack" plus a half turn.

Then put the darned thing on a chassis dyno and see where the afr is at wot. Unless you have wideband and data logging, that system is not gonna tell you.

I had a 350 with that same cam and AFR 195 heads. Compression was 10.2/1. Ran 3500 stall, 3.90 gears, vic jr manifold and holley 700 DP carb. Car weighed 3550 with me in it and used to run 12.30's at 111. I think somthing is holding you back. Also, with that cam, I used to shift at 6300.

Thats just it. I have no clack at idol. I have checked the lash. I agree that I probably need to tune it on a dyno, but hate to waste the money when i know that a dyno chassis tune is not going to get me 1-1.5 seconds... There is a limiting factor here that i am not seeing, and that is what i am looking for.

This I know....

My heads are good enough...
My cam is there...
My exhaust flows well enough...


That leaves my Holley system with spark and fuel mixtures. Unless something else is wrong. Can i see a full second out of the car tuning that? I dont think so. Anyone lost that much time with the fuel map and spark being off...I know my spark is not quite right, but not terribly off.

Im looking for longshots here guys. All ideas are appreciated.

how do you set your lash ?how can a roller cam go flat ?how do you know if your rich or lean ?plugs ,wideband o2 sensor?lots of unanswered questions here:)