I am considering a roller cam conversion on my LS5 454 from a 71 Corvette. I don't want to lose any vacuum, it's low enough. What cam would you guys recommend?

 

Depending on the cam you get end up with more vacuum than what you have right now. ROller cams allow more lift with less duration so you could potentially get the same or higher lift you have now with less duration and your vacuum would go up

 

Yes sir, well aware. I was not asking theory, I was asking for a specific cam that someone had used and works good for them. My fault for not being more specifc in the question. Thanks

 

What are the specs of your current cam? A modern roller profile with less duration and similar or more lift will make at least as much power with more idle vacuum.

I had this profile ground for Shmoky (a member here) as part of his 454 build and it's going to be a good all around profile, but since the car is up in the north practical experience will be a few months away.


CB 3014B/3035B HR 113.0
Gross lift .606/.601
Duration at .006 268/276
.050 valve timing

open 0, 38 close ABDC int
open 49, -5 close ABDC

Cam installed at 109 ICL

218/224 @ .050 duration
.357/.354 lobe lift
113 lobe separation

 

I used a Comp cams 270 in my 454 build but PROBABLY would have been better with the 280. By about 4800 I am pretty well done. I have GOBS of "low-end" torque though.

 

Thanks Rust B. The cam now is stock LS5, as far as I know. I bought the car the way it is, pretty much. I've done intake, carb, ignition, and front of the motor. I'm not sure about the cam yet, just trying to do some homework just in case. Thanks again, Tank

 

lunati #60231 solid roller voodo series. mine is 489 ci. with this cam, 15" vacc at idal @ 800 rpm. my power brakes and headlights work fine. pretty awsome power and trq for street. i like it

 

Thanks to all that replied. Ive picked a cam.

 

That didn't take you long to decide on a cam Took me well over a month even with rustbucket79's and other forum members help. What cam did you decide on?

shmoky

 

I've been looking at cams for awhile. I'm gonna go with a roller that emulates the LS5 cam, just in roller form.

 

I have witnessed a Comp XR276HR cam go 12.60@115MPH in a 1971 LS5 Corvette with a M-20 and 3.36 gears at the Vette Magic drags. My friend built the motor, the 454 had 2.19/1.88 valves with pocket ported iron heads, Edelbrock performer intake (not a RPM but, a std Performer.) Hooker chassis headers, good exhaust and Drag T/A tires. The owner drove it about 100 miles to the strip, raced it and drove it home. Here is a link to Comp's hydraulic roller pages: http://www.compcams.com/technical/Ca...01_227-228.pdf

 

You're going to all the trouble to copy the LS-5 cam? Just in roller form?

Why?


The LS-5 cam was barely decent enough for a smogged station wagon.

If you're going to all the trouble to change to a roller cam, might as well step up the program IMHO.

A flat tappet LS-5 cam sure isn't going to wear out any parts..so why change it if not to improve it?

But hey...that's just me.


JIM

 

Jim, for some unknown reason, I really do agree with you but, I'm not out to make a 10.0 drag car. My LS5 seems to have plenty of power even right now. I would say it definately has the 365 advertised HP. I'm tired of the oil situation, and a roller cam would fix it. I don't think the LS5 needs to be "improved". This car got my attention REAL quick when I put it back on the ground, and drove it again.

 

There is no "oil situation" for the properly informed. Brad Penn Racing oil, Joe Gibbs oil, Mobil1 motorcycle oil, Motul, Valvoline "not for street use" racing oil, Castrol is said to be comming out with a Syntec "Classic" oil with ZDDP. If your LS-5 is running well and your happy with the performance, let it be! Buy the right oil, the only "oil situation" I can see for your LS-5 is $5 a gallon fuel costs

 

And I need a jacka** like you to tell me that I'm uninformed? Of 37,000 sperm, and you're the one that made it?

 

Tank,

I am curious, you are NOT interested in increased performance from an HP stand point and you say that a hydraulic roller will address the "Oil situation" best. You need to explain a little bit more.

What "Oil situation" are you talking about? Oil usage in the engine? High gas prices?

If the engine uses oil, you need to find out where it is coming from and address that issue. Valve guides, worn rings etc. A cam change will not effect any of that.

If the latter (high gas prices), put your big boy pants on and realize that you purchased a "Gas Hog" and NOTHING will significantly improve that. You aren't going to take a 10 MPG vehicle and change it into a 30MPG with a cam change.

A 454 powered machine is a "Too hell with the price of gas, I want to go fast" type of machinery. If it is a daily driver and operating expenses are too high, buy a beater Honda and make the Vette a toy. You can probably buy the beater for what the engine upgrades will cost.

Just an old man's point of view who as "Been there, done that".

Bob





What oil

 

Bob,
I've been there, done that too. I've been around race cars since I was washing parts when I was 11 or 12. This "oil situation" that seems to have every damn CF member up in the air about is nothing more than using any oil. I will use what I think is the best oil, still. Enough on the "oil situation", that got blown WAAAY outta proportion.

The engine is in very good shape as far as I can tell. Compression, and leakdown checks are good.

Was the "10MPG to a 30 MPG" comment an attempt to insult my intelligence? Like I said in an earlier post, I don't need a lecture on the theory and operation of a camshaft, I wanted info from supposed inteligent CF members about a cam that worked well for them, without a "listen to me, I know all" kinda attitude.

It's easy to answer this post, "Tank I used a XXX cam #XXys and performed great for me". There, done.
What I do with my Corvette and how I do it is determined by me and no one else.

I'm not trying to pi$$ anybody off or make anybody mad. I just wanted a serious answer from somebody that has used something that I might not have used. This is the first big block I've owned since 1976, and it was a Ford.

Is this post indicative of how the forum answers all posts? And jumps to conclusion, because each and everyone of you has more knowlege than God?

I know that there are some good people on this forum, I've seen their answers to some others questions. They did it with intelligence, dignity and some serious high class.

Thank you all for your answers, I'm appreciative for your time. Tank

 

BigBlockTank...

I know you're not building a 10 sec racer here. Most of us aren't that crazy!

I spend a lot of time trying to help people select a good cam for their combos. There are so many ways to *miss* and pick something all wrong for that person...when it might be perfect for another with different parameters. That's why I didn't even make an attempt. No way would I recommend a cam without having a LOT more info.

Has engine been rebuilt?

What compression does it REALLY have now? Often rebuilds are even less than the pathetic result that GM gave us. Very common for an LS-5 to measure under 8.0 actually.

Are heads stock?

Intake, carb, exhaust?

Trans/converter- wide ratio or close ratio stick?

Rear gears?

A/C, PS, PB?

What are the real traits you want? After your post about being pretty happy with the power it had when you drove it..I have a lot better idea of what you consider streetable. Some people are willing to put up with different manners and like to tune it to perfection to get the best of both worlds. To recommend a cam without knowing exactly how you like to drive it would be an injustice to you and anyone else who reads this thread.

There are tons of cams out there that can have better manners than the LS-5 and pick up substantial power as well. The LS-5 was smog era stuff and it can definitely be improved upon.

I'm assuming the oil situation is about the reduced zinc levels. The good news is the LS-5 cam is mild enough that it won't put much wear on anything and yours is already broken in..so you have the biggest hurdle behind you. As mentioned there are good oils out there..you just have to find them. I found some old style CI-4 diesel oil last week and bought it. For no more miles than most folks drive this stuff....I'm beginning to think the high $$ race oils aren't that big of an issue. Maybe change it once a year or so.

I just opened my 540 up this evening. I pulled the solid roller lifters out to send in to be rebuilt. I don't put 10K miles a year on it..but it does get at least 5K or so..plus as much drag strip action as I can get. I've been running VR1 20-50 on the street most of the time and most of this last year I left some Royal Purple 10-30 street oil in it that I had put in to go racing. Good news was that everything looked great. No visible cam or lifter wear. This cam has .774/.731 lift with some serious springs. Solid roller lifter rebuilds are just part of the territory for race motor type stuff...especially when you use them on the street. But these have been in there longer than I should have left them...several years now.

The average mild flat tappet I bet would be fine with some good race type oil, or CI-4 and maybe even some Crane cam additive if you were really worried about it.


JIM

 

Jim,
Thanks for the response. I know I didn't give much info, and it was intentional as well.
I've been a crew member and crew chief on 8 sec. cars. One was an alcohol dragster that ran 8's and into the 9's when I started chiefing for him. We got the car to 8.22, but had to slow it down to 8.30-8.40 for the driver's comfort (hooked too hard on the line). The other was a steel body Nova that had a 615ci 1165hp engine that ran 8.02 (best time done in TX).
I really have "been there, done that". I'm not slowing down, just want a good streetable 1971 LS5 454 in my 69 coupe, with all 365 horses out of it, that's it. I don't give a monkey's butt how much MPG's I get. It's a 454 for God's sake. (haha)
The compression is pretty fair, 150-139 spread over all 8. Leakdown was good too.
It has a TH400, 3.08 gears in the rear (best I count) stock heads, exhaust, converter. I put a GM Performance intake and a 750 vacuum sec. Holley. Only put a Holley for the hood clearance (air cleaner). It has A/C (new), P/S, P/B (new).
I'm not really sure that the cam is getting changed. The car has been on jackstands for almost a year. If something happens now, I'm gonna have a clue what I want to do and do it in a week or so. Planning, planning, planning.
I don't know it all, that's obvious, but I have been around for a few minutes.
I knew that there were some intelligent, friendly people on this forum. Thanks Jim

 

You might shoot a PM to Zwede here on the Forum. Tell him I sent you. Markus has an original LS-5 car..but with a stick. He's been playing with it for years. It now used Edelbrock 100cc chamber oval ports, headers and Holley EFI. But he runs a Tremec trans and 3.08's..so it definitely has to have nice low speed manners to handle the O/D with a stick and 3.08's as well as A/C, PB and PS he has on his car.

He's ran a couple of different cams..all hyd rollers. Most recently a Voodoo Lunati and he seems very impressed with it's manners and power. See what he says..might save you some time.

With only 150 psi tops for cranking compression you could use a lot faster opening lobe with a tighter LSA to build some cylinder pressure. You can still maintain good manners with cams in the smaller duration ranges. You won't be revving much over 5000 rpm most likely, so the tighter LSA will really help the midrange. Just have to balance it so you don't get too much overlap and destroy manners. But again, with lobes like this it won't be an issue. You can easily go out into the .550+ lift range to gain some power with your heads..which are actually pretty decent.

JIM