[dmac]

helping to pick a cam for 400 stroke to 466. KREs unported, D-ports. I suggested 10.25:1 cr, He `doesn't want to leave power on the table. He is intent on using the 1.65 rockers he already has.

I suggested either the crower 60919, or 60245 with vmax rhoads. No issue with the ticking noise. 1 7/8 headers into 2.5 exhaust with crossover. Currently a 2000+ stall, planning rear gears of maybe 3.23, maybe 3.08' I think that the 60245 with rhoads will act the same as the com 274XE at lower rpm, but then perform better at higher range.

Any thoughts? Please.

His machine shop suggested Comp 274XE cam and 9-1 cr even with the aluminum heads. He is an old time machinist, but sees very few Pontiacs these days. This needs to be driveable, without being too loud, automatic, power brakes but he may take it to the strip. He used to race a mustang II with a built 302 that he couldn't drive at all on the street. He always let shops build what they chose, so isn't used to selecting cam, etc.

[Blued and Painted]

Cant seem to find the 60245. Since your going off the shelf flat tappet, Im thinking the solid 60310 with the cool face lifters. You will need more stall. Any larger and the power brakes wont work. The solid gives you some flexibility using valve adjustment.

[dmac]

Here's the specs for the 60245 -

[dmac]

Here's the specs-

Crower 60245 (HDP) Ultra Performance Cam
Adv. duration 311/316
.050 duration 248/253
Lobe sep. 112
.512/.524 lift w/1.5 rocker

My thinking is that with rhoads lifters, it would act like a smaller cam for street, and give him max performance at the track. I know he wants to race it. And he wants hydraulic flat. I am thinking that the shop suggesting 9:1 for cr with the aluminum heads and the comp cam show that they aren't real aware of Pontiacs. If he wanted 9:1, he could stick with his current heads and just get them ported. 9:1 cr isn't taking full advantage of the KRE heads.

[Blued and Painted]

Bump

[Cliff R]

9 to 1 compression with KRE aluminum "D" port heads? I'd go the other direction with the compression ratio if you are looking to effectively use a cam with 248/253 @ .050" duration.

Even with the 60919 I'd shoot for 10.5 to 1 compression. It will run fine on pump gas with correct tuning. My 455 is 11 to 1 on pump gas with the KRE heads (76cc chambers). I even feed it a steady diet of 87 octane fuel and it's never once even thought about pinging.....Cliff