[4birds]

Looking for somee suggestions on Hyd roller cams and lifters. Car: 72 T/A 455HO, 8.5:1 CR, Q-jet, port matched HO intake and 7F6 heads, R.A.R.E. 2.5" manifolds with Flowmater crossflow exhaust, M22, 3.42. "High spirited" street driving with an occasional trip the the drag strip. Elevation here is about 4400 Ft above sea level. Had a 041 cam with Rhodes lifters and was very happy with its performance, but looking for a litte more. Is the cost of going to a hydraulic roller worth it? Please give me your opinions. Thanks!

[Rocky Rotella]

You'll probably find greatest performance with a custom cam. We created a 224/236 hydraulic roller from Comp Cams for the 455 HO in my dad's '72 Trans Am. It idles well, street manners are excellent, and it has plenty of top end charge. We documented the build over three issues of HPP and that included engine and chassis dynoing.

http://www.highperformancepontiac.co...fix_up_part_1/

http://www.highperformancepontiac.co...fix_up_part_2/

http://www.highperformancepontiac.co...fix_up_part_3/

The compression difference will likely knock a few hp out of your end result but the article will give you an an idea of how well your engine can perform.

[Cliff R]

+2 on a custom grind. We use a 230/242/112 custom HR cam in the 455 HO and 455 Super Duty applications. I've built several of those engines here, and spec's out the same cam to a few folks building them. It's shorter duration at .006" than the 041 grind, but will make a tad more power with much better idle quality and low speed manners.....Cliff

[4birds]

Thanks Rocky and Cliff. Do you have the camshaft grind #'s that I could order from Comp Cams?

[72LuxuryLeMansLa.]

Originally Posted by 4birds

Thanks Rocky and Cliff. Do you have the camshaft grind #'s that I could order from Comp Cams?

I would call Cliff and give him all of your specs and driving goals, let him spec the cam and then make a few bucks for his trouble by buying the cam from him.

[Cliff R]

The cam is not from us, we were instrumental in selection and testing it. It's a home-run for the lower compression 455's with manual transmissions. For the auto transmission set-ups it will need a good converter with at least 3000rpm' flash stall, or we'd go slightly smaller to something closer to what Rocky used.

The problem with the HO and Super Duty 455's is low compression. They have BIG potential from the round port heads, but camshaft selection with them is critical. They need a pretty big cam to bank in on the big head flow, but big cams and low compression come at a price.

They are perfect candidates for a modern HR set-up, where you can keep the seat timing shorter and still tap in on the big head flow and strong upper mid-range and top end power. Any flat cam big enough to do the same thing is going to REQUIRE Rhoad's lifters, and it will need plenty of duration as well.......Cliff

[steve25]

At least you have the better year HO head in regards to pumping the exh out thru the manifolds due to there greater low lift flow numbers!

[GTOLou]

Bought a TA years ago w/ a 455, 6x heads, dished pistons - it probably was 8:1 at the highest w/ an "off-the-shelf" 224/230 HR 110lsa. Very, very tame cam/combo. Pretty much like a station wagon. Swapped to eheads, 72 cc's and ended w/ compression of about 10:1 and put in a 230/236 HR - 112 (I think) with a recc from Cliff. Idle, low-rpm cruisability, vacuum were all great - but clearly would them pull well to 5000++ RPM. The other cam would not. Not sure I'd use 224 on the intake in a 455 - unless I was setting it up for parades and to help teach my kids how to drive a stick..