LS6 cam or Modern equiv in SS454 Monte

[aaronkl84corvett]

ok, i know this is a yenko page - but i also know alot of you guys run in FAST and Pure Stock....

so - i own a 70 SS454 Monte - It has the original LS5 - but previous owner put 9:1 flat tops in, and left the rest of the motor stock including the LS5 hyd cam.

The car has its TH400, and 3.31 posi - i've been tweaking it with timing and carb tuning this year and finally have it running quite good but as usual, its not enough [img]<<GRAEMLIN_URL>>/laugh.gif[/img]

so.... i was thinking, i have an original OE LS6 camshaft, and a set of closed chamber oval port heads that have been mildly ported and LS6 valves/springs installed - they had some bowl work done on the exhaust side. They would bring compression up to about 10.25:1 - (10.5 if i use a shim gasket like they did back in the 60s)

Question is - for a regularly cruised vehicle - should i go with this LS6 cam, have Cliff Ruggles mod the Qjet for the cam and run with it - or sell the OE cam, and go with something modern that will work with a 9:1 454? I'm a sucker for original equipment HP stuff... but i don't want to put too many mismatched parts on this car.

i intend to keep the stock manifolds and functional AC [img]<<GRAEMLIN_URL>>/laugh.gif[/img] i know more than a few guys who drive ACequipped L72 cars around Detroit without issue - but they are Camaro's not the big Monte!

Any help would be great.

Cheers

Aaron

[Zman1969]

Since no one has stepped up, I would say that wouldn't be a great match, as the LS6 cam was engineered with 11:1 comp not 9. I suggest contacting a Eric at Vintage Musclecar parts- a sponsor here and give them the specifics for their recommendation. IMO LS6 cam in 9:1 motor would be a dog or worse. I know this firsthand as I have been there and done that, Eric knows his stuff

[WILMASBOYL78]

Talking with Eric is a good idea...he knows his way around the BB Chevy motors.

wilma

[Alss]

I would stay away from any flat tappet camshaft...asking for problems.

X2 for Eric!

[EZ Nova]

Do yourself a huge favour and get with a cam guy like Chris Struab and get something for your set-up. Best money and results going that route.

[VintageMusclecar]

Aaron;

What heads are on your engine now?--they should be closed chamber oval ports (290 castings) if they're `70 LS5 heads.

Assuming a standard bore and flat top &quot;rebuilder&quot; type pistons (which usually wind up ~.020&quot; or so down in the hole) with a ~3 c.c. intake valve relief, a 106 c.c. chamber and a .018&quot; steel shim head gasket, compression would be roughly 8.8-1. I definitely would <span style="text-decoration: underline">not</span> run the LS6 cam with that combination, esp. with a stock converter, a 3.31 gear and A/C.

The factory LS5 cam isn't bad, but there is room for improvement. A mild hydraulic roller would be a nice addition, but given your constraints, I'd advise erring on the conservative side. If you're willing to take the chance on a hydraulic flat tappet, there are ample choices there as well.

In all honesty, I think you'd find more performance improvements in a good torque converter and some more rear end gearing than you would in a cam swap. A quality free-flowing exhaust system is also paramount.

[aaronkl84corvett]

yes they are 290s - i've not been into the motor yet - but the previous owner swears that the measured compression with standard felpro gaskets - was 9:1 but assuming they used off the shelf parts - perhaps comp is a tad below as you suggest..

the LS6 cam is officially off the table for me - I have (what I thought was a NOS LS6 - turns out its a NOS 181 and while i'd love to build a 12.5:1 ZL1 - it ain't in the cards now - and certainly not for this monte)

i have a set of closed chamber heads from 66-67 - I think they are 206 heads from a 396 - and they have 97CC
i figured, cut em a few thou, run the shim gasket - that'd get me dang close to a true 10:1

that all being the case, they don't have the sending unit ports in them, and the intake doesn't allow for one either.

where else could I put a temp sender? that is if I want to run the factory style intake, or even the 390hp aluminum qjet intake (def want to keep it factory appearing)


i'm not afraid of a flat tappet cam - especially with GM EOS on the shelf - but a hyd roller isn't out of the question.... but I don't want to get into full roller rockers unless they fit under the low profile valve covers... i do haev a complete set of the LS6 long slot rockers - they were on the engine that teh 181 cam came out of so i'm sure they can handle the 600 lift... just not sure how good of an idea it is to use stamped rockers with a roller camshaft....
cheers

Aaron

[VintageMusclecar]

(*edited* info re: intake)

If an aftermarket intake is an option, there's the Edelbrock Performer, Performer RPM and the GMPP oval port 12363420 intake. All have temp sender provisions and will accept a Quadrajet, and if the OEM look is a must, a little orange paint goes a long way.

Stamped steel rockers will be fine with a mild hydraulic roller.

[aaronkl84corvett]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: VintageMusclecar</div><div class="ubbcode-body">(*edited* info re: intake)

If an aftermarket intake is an option, there's the Edelbrock Performer, Performer RPM and the GMPP oval port 12363420 intake. All have temp sender provisions and will accept a Quadrajet, and if the OEM look is a must, a little orange paint goes a long way.

Stamped steel rockers will be fine with a mild hydraulic roller. </div></div>


well, i'm more concerned about having factory parts - and there were several 427-390 hp intakes that I could use.

but is that 3/4- 1 point of compression worth the headache by switching heads and all if i'm gonna go with a modern hyd roller cam?

[earntaz]

Eric -- so what about roller lifters ... some are junk and will not last on the street ... TAZ [img]<<GRAEMLIN_URL>>/dunno.gif[/img]