If hes using a stock thickness gasket his compression is only going be 10.0:1 which will kill his torque. Hopefully he atleast used a thin gasket to get it back up to stock.

 

yep. didn't read all the specs, but with a build like this, I'd hope some attention was paid to the quench and DCR. I ran a cam similar with the same compression (big mistake, another story), and made decent power, so it can be done. Is it preferred? Nope. Will it detonate? Not likely.

 

Bret, Comp recommended the 987's on that first setup. For the second cam, I spoke with Cam Motion first to determine the seat pressure that I would need, and then talked with Comp to determine what spring to go with that would meet those requirements. What should I have used instead?

Yes, definitely. The second setup feels very slow until about 3000 RPM.

 

Also, I corrected an error in the first post. The chamber size is 54cc, not 58cc. I am also using an Impala head gasket.

Keep the replies coming guys. I am determined to figure out what is wrong with the setup.

 

The GM847 is a higher end cam anyways. You really wont feel much of the power untill u get over 3k moreso over 4k. Thats when that cam really takes off. Hence y auto cars go with large stalls so that they stay in that power band

The 503 is a great all around cam. Good low great mid and decent top end. Its all on what u want out of your settup. Great for a stock or mildly headed car and makes good power.

Since most of the cars in my area are LS1s and a very small bunch of fast 4 bangers with ALL TOPEND i went with a cam that will perform up there. And its not really outrageous

just ask yourself on what u want out of your car and who your competition is

and again , when racing how often are u gonna be below 3k? Unless u want a street cruiser and dont want to be revving to 6800 then the gm847 isnt the right cam for u.


Honestly id check what u knwo is already the problem. Do somthing about your rear end and recheck the valvelash. On stock cubes there is no reason y you shouldnt be making 400rwhp.

 

those springs will work fine with that first cam.

 

Crap, my typo's are killing me today

Comp recommended the 987 on the first cam, 977 on the second cam.

From Comp's valve spring chart:

987
1.800" install height
370 lb spring rate
121 lb @ 1.800" height

977
1.850" install height
441 lb spring rate
155 lb @ 1.850" height

 

You were definatly getting valve float after 6200 with the 503, and it looks like you might be getting valve float at 6500+ with the new cam, a 1.5" diameter spring has to be heavy as hell along with the retainer.

 

I forget exactly but the mass difference of a 977 vs a beehive is about double!

No doubt you are feeling the lack of midrange TQ with the new cam, you just can't have that much duration that late and make any midrange TQ.

Bret