GMPP Hot Cam specs needed...
This is a discussion on GMPP Hot Cam specs needed... within the Internal Engine forums, part of the LSx Technical Help Section category; I am building a 440 Pontiac for my 1971 Lemans Sport. Included in this build is a set of 85cc ...
05-09-2010, 03:18 PM #1
GMPP Hot Cam specs needed...
I am building a 440 Pontiac for my 1971 Lemans Sport. Included in this build is a set of 85cc Kaufmann Racing (KRE) cylinder heads. These heads have much better ports than stock and modern heart-shaped combustion chambers. This got me thinking that perhaps the best cam for it would not be a traditional Pontiac grind but a LS-type grind. I am looking at the GMPP "Hot Cam", p/n 88958733, given the difference between a 346 and 440 in airflow requirements. Does anybody have a copy of their cam timing card to look at so I can tell Delta Cams what to grind my ancient billet Isky Pontiac to?
1971 Pontiac Lemans Sport convertible
440 Pontiac w/Q-Jet and Ram Air III exhaust
TH-200-4R w/BRF valve body and 12" Continental convertor
3.55 BOP 10 bolt Limited Slip
05-09-2010, 04:27 PM #2
The hot cam is made for the Ls1, or LS2 and I suspect you will want a bigger cam with a 440. You will also need roller rockers to accomodate the lift and ramp of the LS type cam. I would talk to the cam companies for a recommendation for your build.
88958733 LS Hot Cam
I: 219 E: 228 (1.7 rocker) I: 525 E: 525 112
05-09-2010, 04:43 PM #3
Roller rockers and the like I do have - even the correct 1.7:1 ratio. I need the timing events, IVO, IVC etc. to have the cam ground correctly.
05-11-2010, 09:47 AM #4
We've used Kaufmann heads on large cube pontiac builds. You didn't mention if you are using their own design of D-port heads or the Edelbrock castings that Kaufman CNC ports.
But either way, for best results, contact Kaufmann and have them spec a custom ground camshaft for your setup. Nobody knows their heads and what they like better than the manufacture of the heads (Kaufmann).
05-11-2010, 10:25 AM #5
Kaufmann's own design - I had no interest in a 40+ year old RA4 head design the Edelbrock is currently making. I will see what Jeff has to say.
05-11-2010, 12:36 PM #6
05-11-2010, 02:31 PM #7
See, here is the issue: I am building a daily driver - not a street beast. The whole reason for these heads is to get the modern combustion chambers. I like the way my 2004 GTO drives around town, and would like my 71 to emulate this. This car will have a 12" convertor. Most of the aftermarket Pontiac vendors know/want to build an animal. - the current cam of the month is the "old Faithful" grind, around 236/244. I do not believe that will go well with a OEM type convertor.
05-11-2010, 06:55 PM #8
With a 440, if you stay around 230 or a little less at .050 and a lobe sep of 112-114, and with a tight converter and 3.55 gears, and shoot for 4 degrees of advance, it should be able to be tuned well enough to work with that converter.
The Comp XR276HR (hydraulic roller) is pretty close to that. They also have one size smaller than that, which would idle baby butt smooth and make gobs of torque in a 440.
Comp will even change the grind around a bit for your particular build to suit your needs if you aren't having any luck with the pontiac builders.
You basically have Kaufmann (Ohio), Butler (Tennessee), and Fulper (California).
Those are the 3 bigger players. I've personally dealt with both Kaufmann and Fulper and have nothing but good things to say about them. I've never done anything with Butler so I can't comment.
There are other somewhat new comers in the Pontiac world that have been around for a few years, but I would think one of those 3 would taylor a camshaft to what you need to do.
Last edited by Firebirdjones; 05-11-2010 at 06:59 PM.
05-11-2010, 09:05 PM #9
This is interesting: the cam you spec out, 51-423-9 note how much it differs from the LS grind I was looking at...
What throws me is the 068 cam of yesteryear runs
IVO 31 BTDC IVC 77 ABDC 288* (212* @ 0.050")
EVO 90 BBDC EVC 32 ATDC 302* (225* @ 0.050")
Only thing I can see doing this is the Comp Pontiac piece must have some hellish ramps!
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