cam change

chuck smith · 09-30-07, 02:52 PM

while I have my interior out and putting in the new shifter from Ian and putting the webers on, I am thinking about changing cams. I have no idea of the specs on this cam but it is a hyd flat tappet cam and seems to be of fairly high lift and duration. Any suggestions on a suitable hyd roller cam for this 302 with SVO aluminum heads and 48 IDA's? It is a roller block so I can add a spider and roller lifters. thanks. chuck

Big-Foot · 10-01-07, 08:38 AM

Chuck - I much prefer the rollers to the flat tappets. Particularly since the EPA has mandated the removal of zinc from motor oil - this is causing excessive wear and failure of flat tappet cams.. Which cam is best for you - well, that would depend upon your needs and how the car is geared. It's exceptionally easy to go overboard with a 302 and now you have a car that may sound cool but is a driveability nightmare etc..

Bill D · 10-01-07, 03:19 PM

Webers hate long duration cams. If your going to switch cams, call Inglease or Redline and ask for a recommendation.

Jac Mac · 10-01-07, 03:58 PM

Only thing I will add Chuck, the flat tappet cam might have a slightly higher rev limit to what may be acheivable & safe in the roller hydraulic, if that is a factor in your choice.

Jac Mac

Scott Calabro · 10-01-07, 08:33 PM

Chuck 1,

For what its worth, I've chosen Holman Moody's "C30Z" solid flat tappet, (HM p/n c30z-6250-c) for my 10.5 to 1, 289 with 44 IDF's.

With this cam only 120# on the seat is required.

I am using Crower "Cool Face" solid lifters to minimize lube issue's.

Randy is correct about the additives, but Shell Rotella 15w40 has plenty of Zinc.

Also any GM dealer parts desk will sell you GM break-in lube that has zinc. This can be added at each oil change.

Cheers,
Scott

John Fitzpatrick · 10-01-07, 09:14 PM

Scott-
Are you happy with that cam? .478 lift seems low compared to what others around here seem to indorse.

Scott Calabro · 10-01-07, 09:35 PM

Toy264,

The engine will go on the dyno soon.

I'm only looking for 325-375 hp.

It should work well with the IDF's. I've disscussed it with JACMAC.

Cheers,
Scott

Rick · 10-03-07, 01:26 AM

Scott: I believe that cam is real similar to the old 289 Hipo cam. BTW the GM addative is being removed from their catalogs. NLA after existing stock runs out. Thanks EPA

Scott Calabro · 10-03-07, 07:56 AM

Thanks Rick,

I'll run out and get some!

Yes the HM C30Z is the 289Hi Po grind.

Cheers,
Scott

Big-Foot · 10-03-07, 09:18 AM

STP (Yes the stuff that Andy Granatelli sold) still has a pretty high percentage of Zinc in it - it's called ZDDP. I'm back to using that and Kendall Racing oil for flat tappet cam break-in and so far no problems (knocking on wooden head).. The Rotella oil also has high Zinc concentration but from what I've read you'll likely be seeing that reduced to the point where it's no longer available as well as there are fewer normally aspirated (ultra high compression) Diesels on the road that require it.

The other bad thing (and always has been) with flat tappet cams is that they require sustained 2,000+ RPM operation under no load for the first 20 minutes. I've had more than one boil-over during this period in a fully new engine that has a lot of friction being built up in the cylinders during that time. Roller cams don't require this sustained operation and are a much more civil break-in..