Thread: Suggested cam for stock 454

Tweet

New guy here looking for a little advice. I've got a generation VI 454 crate engine with hydraulic cam and litters on a tbi setup. It's got the peanut heads and such. It's going into a 1989 k3500 with manual 4 speed Muncie and 4:10 rear-end. It's going to be used primarily for pulling a trailer with cattle, hay, cedar posts, and ranch stuff. I'm going to put some shorty headers and a cam in it but other than that I'd like to keep it stock. What size cam I get that will give me a little more low end grunt and maybe a tad more horses with a nice lope at idle? I don't want to really mess with the heads right now that's in the future. Just a cam and lifter setup. Oh and the rocker arms are the non adjustable kind which I'd like to keep it possible but not a deal breaker if not. Thanks for any advice

Welcome to CHR:

Welcome to CHR. As you probably already know, the Gen VI was exclusive to trucks. GM made them from 1996 until 2001 so there’s s ton of them out there. As such, there are a lot of aftermarket parts. When you say “crate engine” in the Gen VI it is typically a 290 HP replacement for a truck. There were two versions produced: L29 which is the basic 454 truck replacement and the L21 which has upgraded internals, i.e., forged pistons and crank. The L21 is the better of the two. Both have 4-bolt mains and are roller cam engines. Gen VI also had standard oval-ports with 102cc chambers - so if you have peanut ports; it’s not a Gen VI.

The bad news is this – there is no simple cam upgrade for this engine. As you mentioned, the Gen VI featured a non-adjustable valve train, (like most late-model big-blocks). The folks at GM designed this engine for low RPM and torque so the cam is already ground in that direction. Virtually any deviation from the factory cam specifications will require compatible rocker arms and valve spring upgrade. That said, a mild upgrade like a COMP Cams Xtreme Energy Camshafts 01-412-8 will work, but I’d still recommend valve springs. You definitely do not want a lot of lope at idle as that typically indicates a poor choice of cam. Only kids think the flatulating elephant sound is cool and what your hearing is the engine struggling to stay alive while raw gas pours out the exhaust. The overlap will also kill your low RPM performance.

Another approach would be to ditch the TBI (if your state allows such from a DEQ/smog regulation standpoint) and drop on a Weiland Stelth manifold with an 800CFM Quadrajet and some long-tube headers. I think you’d see a 50HP jump and without tearing into the internals of your engine.

Regards,
Glenn

It's definitely a gen VI block. It's got the aluminum timing cover with 6 bolts and the smaller freeze plugs. However the block number is a mystery as I can't find it on any database. It's 12561359 and the casting is crystal clear so the 9 is not a poorly stamped 8. I've already asked several sources about this and all anyone can say is that towards the end of the manufacturing run for these engines GM did a very poor job at keeping records. It's got a hydraulic cam and lifter setup with a TBI intake and heads. I can't remember the numbers on the heads but when looked up they are listed as heads that go on a crate engine. I bought it used with less than 5000 miles on the engine and it came out of a 1995 K2500. I don't mind changing the lifters and rocker arms and push rods along with the can if I can do so without pulling the heads off.