280H cam question

building up a 400 and cant decide what cam i want.

400 block 30 over
scat 9000 400 crank
eagle H beam 5.7 rods
afr 195cc heads
87 octane gas. what compression should i run for this?

what rpm range is the compcams 280H cam going to be most happy with in this build?

and what type of power will it make?


thanks


Register now (free) or login to remove ads

around 2500 to about 6300 rpm.

thats a good streetable range for me.


what type of power?



thanks

My choice for a good strong street motor in this case would be to use the 75cc heads with a KB125 piston (7cc flat-top), 0.005" piston deck height, 0.040" gasket for a 10.05:1 SCR. I'd use a Comp 286H with this combo for a 8.35:1 DCR and use a 2500-2800 stall converter with 3.50-3.90 gear.

RPM HP TQ
2000 152 399
2500 192 403
3000 245 429
3500 313 470
4000 378 497
4500 434 506
5000 481 506
5500 502 480
6000 505 442
6500 470 380

This assumes a high-rise, dual-plane intake manifold such as the Edelbrock Performer RPM or RPM Air Gap, 750 CFM carb and large-tube equal-length headers through the mufflers.

Your stack of parts in this case will be 9.008", so cut the block decks for a block deck height of 9.013" to achieve the 0.005" piston deck height, which combined with the 0.040" gasket, will give you a squish of 0.045".

i would use a 1900-2200 stall converter, no more than that.

so is normal deck height .025? then if i had the block 0 decked would the piston be right at the top of the deck? or would the piston be sticking up out of the cylinder some?

and i have a edelbrock performer rpm intake. and im running a 4 speed manual tranny. so stall is not a problem.



thanks

Nominal stock block deck height is 9.025". Nominal parts stack height is 9.000" (400 crank radius 1.875", rod length 5.565", piston compression height 1.560" = 9.000") Same stack height on a 350 (crank radius 1.740", rod length 5.700", piston compression height 1.560" = 9.000")

It is desireable to use the tallest stack of parts you can so that in setting the piston deck height and squish, you have to cut the block decks the least amount possible to get where you need to be. In this case, if the block is virgin at 9.025", then you'd need to cut the block decks only 0.012" to reach the proper 9.013" block deck height in order for your 9.008" stack to fit in the block with a 0.005" piston deck height (piston in the hole 0.005" at TDC).

I had an 80 camaro with 3.42,s ,041 heads,flat top pistons,hei,670 street avenger carb,edelbrock intake,roller tip rockers,headers with dumps.
It had an rv style cam.I bought a 280H to put in it.
That cam ran great with the above combo.It was strong right off idle up to 5500,I shifted then.

i have 5.7 rods though. not 5.565. will 8.35:1 run on 87 octane gas?


thanks