competition products sells a new hydraulic roller takeout cam and lifter packages for $199.95. a friend is building a 454 for his 71 ss. he wants to put in the following cam. .576in-.588ex lift. adv. dur is 250-256. dur@.050 is 226-232. for this money he is thinking of this setup rather than a flat tappet set. any experiences with these cams in a 71 mark 4 block? car will have a performer rpm, b@m 11" converter, small tube headers and 3.73 gears in a 12 bolt. any input or surprises? thanx mike

Think that is strictly a GenVI cam.lifters. You might be able to run the cam if the MarkIV block has the machined retainer flange, but you will need retrofit roller lifters - about 400.00 - 500.00.

thats what I thought also. let me read the add for you. " genuine gm billet hydraulic roller cam and roller lifters. take outs from new engines, when marine engine engine proigram upgraded entire valvetrain. will fit mark 4 and gen 5/6." it seemed too good to be true. thanx mike

I'm not positive but I think the cam is usable with the retrofit lifters available, they mention it in another add in the catalog. Call Competition products.

Just thought I'd add this tidbit of info. The MKIV block will accept the Gen VI cam with no mods. The retainer plate bolts up no problem. Instead of it being oriented at 12/6 O'clock, it's at 9/3 O'clock. See Mike Lewis a.k.a Wolfplace for the retro lifters. Oh ya, the Cloyes timing set is recommended. You can only get a single roller chain under the cover, that's the other catch! Oh ya, and shorter pushrods for the retro lifters. Mine came out to 8.4 Exh/7.5 Int., but you have to check your specific length. And the lifters ain't cheap.

if he can't use the lifters that come with the cam i'm sure he will just use a flat tappet. the $199.99 is for the cam and lifters. thank you all for your input. mike

Mike,

The cams are Re-Grinds from an original .510 lift .224 duration 115.5 LSA 330 HP Mercury Marine Motor. You can use a 502 Timing set single oversize roller for $45 from GM. The lifters you get are Gen VI takeouts from the marine motor.

Excellent torque motor setup particularly in a boat and heavy vehicle. I have much experience with this setup.

thanx for the info tom. what would he need for pushrods, springs/retainers and rocker arms? it is a 454 block out of a 71 ss with stock heads. is it a worth while swap? thanx again mike

ttt

..why not just call Competition Products tech line?

because I would like first hand experience if anyone has actually used the cam in any combo. thanx mike

Straight answer - here goes:

IMHO and experience, a single pattern cam with a .050 duration of 230 @ .050 (just for example - not really sure from the posts here exactly what duration you would be getting) on 115.5 LSA will have "-1" deg. overlap at .050. The advertised duration numbers are not accurate, I would place advertised/seat at 288 - 292 for a cam with 230 @ .050, using 290 as seat timing you will have 59 deg. overlap at seat based on the 115.5 LSA. My guess is this cam will have very smooth idle and a power range of about 2500 - 5000 in a 454 motor.

Personally if I was going to go the expense of a roller in a MkIV motor (mainly the $400 - 500 for hydro rollers), I would consider a number of other cam grinds first. I prefer 110 - 112 LSA for my street cams.