Cam grinding

[efnfast]

Soooo, how do you grind a cam and give it more lift? Seems to me if you grind it you'll give it less lift. Longer lifters and grind on the closed side? TIA -Steve

[LGAFF]

The base cricle is reduced so in relation to the reduced base circle there is more lift

[Dynomite]

The base cricle is reduced so in relation to the reduced base circle there is more lift

Since you are reducing base circle you have to check Lifters to make sure you do not run out of Lifter uncompressed Height.

See 10 Posts regarding Lifters/Valves/Camshafts LT5 New Rebuild Issues (Lifters and Camshafts) (http://forums.corvetteforum.com/c4-zr-1-discussion/2942622-tech-info-lt5-new-rebuild-zero-compression.html)

And......since you now have more Valve Lift you have to check Camshaft Timing to make sure you do not have Valve Interference with Pistions at TDC (the Eyebrows)

CAMSHAFT TIMING
Post 21 - LT5 Camshaft Specifications and Camshaft General Timing (pinning) (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-2.html#post1581302479)
Post 22 - LT5 Camshaft Specific Timing (degree wheel) (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-2.html#post1581302481)
Post 23 - LT5 Camshaft Timing Additional Tricks (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-2.html#post1581302483)
Post 24 - LT5 Timing Diagrams and Timing Chain Effective Lengths (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-2.html#post1581302484)
Post 25 - LT5 Timing Chains and Sprockets (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-2.html#post1581302485)

[efnfast]

Thanks guys, every time I heard about cam grinding had me thinking.

[Bob Eyres]

Got me thinking too. I've often wondered why LT5 reground cams are so expensive. Even considering the fact that there are four of them.
If there is a program for the grinding machine, it's not a long "hand labor" situation then it should be a pretty straightforward procedure to do four cams.

Maybe I'm just "livin in the past". Remember the "Corvette Duntov Cam" for small blocks back in the day? What was that? Less than a hundred bucks?

[LGAFF]

Profile development costs $, then you have to do 4 of them and as with anything the rarity of the parts

[efnfast]

What are the down sides of a more aggresive profile? Idle, fuel mileage, more broken parts?

[Dynomite]

Profile development costs $, then you have to do 4 of them and as with anything the rarity of the parts

The Reground Intake gives you the most additional power....not so much the Reground Exhaust....but let Pete the Cam Guru Explain.

Both XfireZ51 and myself have taken a peak at our reground Cams after hours of run time and found nothing out of order in regard to Camshaft or Cam Journal wear.

What are the down sides of a more aggresive profile? Idle, fuel mileage, more broken parts?

Maybe a bit rougher idle (depends if you Regrind BOTH Intake and Exhaust), no appreciable difference in fuel mileage (maybe a bit less), No Broken Parts. Watch carefully when installing Reground Cams regarding Lifters and Camshaft Timing as suggested :thumbsup:

Again....here on this Forum Pete the Cam Guru is the GO TO GUY on Camshaft Regrinds as he has proven in his 1/4 mile times :thumbsup:

You can ask Pete about Camshaft Hardening which is not an issue with the Camshaft Regrinds as the Camshaft Grinding does not get past the Hardened Surface.

LT5 New Rebuild Issues (Lifters and Camshafts) (http://forums.corvetteforum.com/c4-zr-1-discussion/2942622-tech-info-lt5-new-rebuild-zero-compression.html)

Post 21 - LT5 Camshaft Specifications and Camshaft General Timing (pinning) (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-2.html#post1581302479)

[Blue Flame Restorations]

I have Pete's cams in my 91 Turq car. It makes my bone stock Purple 95 feel like a luxury car, in comparison. Man, I'd love to mod that car's engine. :dancing

[Bob Eyres]

So, are you saying that with the cams the 91' is quicker, but less tractable and less easy to drive than the 95'?
I wonder if the combination of my light flywheel and the cams will make it a strong runner, but take a whole lot of smoothness out.

[Blue Flame Restorations]

So, are you saying that with the cams the 91' is quicker, but less tractable and less easy to drive than the 95'?
I wonder if the combination of my light flywheel and the cams will make it a strong runner, but take a whole lot of smoothness out.

I'm sure my 91 is quicker than my 95. The cams do not make it any less tractable in any manner. The engine runs very smooth, even with the AC on in stop and go traffic. Pete really knows what he's doing with grinding and timing. I have a light weight flywheel as well.

The sound of the cams and B&B exhuast is pure music.

The 95 just seems like any other Corvette, after driving the ported, cammed 91.

[efnfast]

Any idea of hp on the ported, cammed 91?

[Blue Flame Restorations]

Any idea of hp on the ported, cammed 91?

500-520 or so. With 4:10's, it's a beast!! Thinking of selling it and modding the 95.

[efnfast]

Shouldn't we do 500 or so without cams?

[Blue Flame Restorations]

Shouldn't we do 500 or so without cams?

Maybe Pete or Marc will chime in??? I've never dyno'd my car. I have intake and exhaust grinds.

[ZZZZZR1]

Shouldn't we do 500 or so without cams?

Marc Haibeck offers a 510hp package without cams. In sure Pete can do it as well but I know of 4 or 5 members with that package

My car has intake cams and I absolutely love them! Wish I did the exhaust cams while I was there....

Love the sound and power the cams offer.

:salute:

David

[efnfast]

Sooo David, you're around 522 hp. 510 by Marc's numbers, that means 12 hp by cams???

[LGAFF]

might be more than that, alot of it depends on the dyno and conditions, including engine condition...some run without an aircleaner thats worth a few HP....how hot engine was,etc

Cams should get you 20-25rwhp

[Blue Flame Restorations]

Then I should be right about 525hp. I have headers and my exhaust is non existent.

[LGAFF]

You can get any # you want on the dyno if you diddle with the system....thats why its hard to compare on dyno to the next

You might have more Brett....

Then I should be right about 525hp. I have headers and my exhaust is non existent.

[Blue Flame Restorations]

You can get any # you want on the dyno if you diddle with the system....thats why its hard to compare on dyno to the next

You might have more Brett....


Yeah, Pete's told me all about the dyno tricks that people play. I'll never dyno my motor. No point for me. I just like the way it runs. After driving Kevin's stroker, I want one of my own!!:dancing

[ZZZZZR1]

Sooo David, you're around 522 hp. 510 by Marc's numbers, that means 12 hp by cams???

No... At the time I did the dyno, I didn't have some of the items marc uses to get 510hp. (Lightweight flywheel and 63mm throttle boy)

My rwhp should be higher than 444 with those two items added. I don't want to give an estimated dyno # because I don't want to guess wrong

Intake cams add 25 to 30hp and exhaust cams add 8 to 10

:cheers:

David

[Paul Workman]

This is more or less typical of LT5s with stock bottom, cams, & TB. The power adders (call this a "base case") is full porting, relieving, headers, X pipe, 3" free flowing exhaust, and Fidanza FW. Numbers can and do vary, but due to the ambiguity associated with different dynos.

http://i185.photobucket.com/albums/x220/6PPC_bucket/Dyno%20graphs/DynoLT510-19-10.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/Dyno%20graphs/DynoLT510-19-10.jpg.html)

Now...Add cams = +25 ±, 63mm TB = 5-8 more, electric water pump = 8-12±. So, in this 508 "base" example, it would put it around 549 chp, or somewhere in the range of 466 rwhp, ±, depending on the dyno ambiguities and phasing differences. (Pete said he was getting 474 rwhp before his last cam change, FWIW.)

Hope this gives you an idea. Aslo, Marc (http://www.zr1specialist.com/) has all this breakout and more on his website.

One more question comes up often, and that is the loss of low end torque that results from porting the LT5. This graph represents the rear wheel torque results I experienced "before and after". And, I'm not alone! Contrary to most of the car rag articles from "experts", I didn't lose, but in fact GAINED low and mid-range torque! You can ask Dominic or Pete, or Marc, or any of the FBI gang and they'll tell you the same thing. As long as you don't go "nuts" with the cams, it is very possible to have some respectable increase in low/mid range torque and wheel power and not loose tractability at all!

http://i185.photobucket.com/albums/x220/6PPC_bucket/Dyno%20graphs/Dynographs_zps723fdad7.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/Dyno%20graphs/Dynographs_zps723fdad7.jpg.html)

And, this is what makes the LT5 unique, and why it surprises so many people - especially those totally immersed in the characteristics of pushrod platforms.

[tpepmeie]

After driving Kevin's stroker, I want one of my own!!:dancing

I'd build another 427 for ya :thumbsup: And I'm less than an hour away from you!

Todd

[Blue Flame Restorations]

I'd build another 427 for ya :thumbsup: And I'm less than an hour away from you!

Todd

Thanks for the offer, Todd. You motor sounds sick!!! (that's a good thing!!!! LOL)

Pete has dibs on the next one. :cheers: Hope to do a 427 too.

[XfireZ51]

So, are you saying that with the cams the 91' is quicker, but less tractable and less easy to drive than the 95'?
I wonder if the combination of my light flywheel and the cams will make it a strong runner, but take a whole lot of smoothness out.

Bob,

You can come and drive my car , then tell me if smoothness is lost. If anything I think its very smooth particularly at cruise. With 350rwtq or more available anywhere from 3-6000 rpm, just keep it in 5th or 6th.

[Bob Eyres]

After seeing those torque specs I don't doubt it. Gee, this engine is phenomenal.