LT1 camshaft suggestions?

[John Brown]

Here is some good reading on camshaft choice for street driven small blocks.

a-tale-of-two-camshafts-st-louis-ncrs

[napa68]

Originally Posted by frankk

Napa what do you mean, it has manners off idle. I would like to find a cam that pulls like the LT1 or better and has a lumpy idle like the 572-720. I had a Sig Erson part # written down from years ago that I wanted to try, but of course now I can't find it.

What I meant by that, is you don't need to slide the clutch at all on an LT-1 cam. No cam burble at 2000 rpm (hence no jerking in a stick car). I can give you the cam part number that is currently in my 327. While I am fine with rough idles, it's not a primary requirement for me.

Here is the 327 I just finished. 10.5:1, pocket ported 461's, Z28 springs. Idle @ 1100 rpm Nothing fancy. Good to 7000.

https://www.youtube.com/watch?v=O7sXG-S5TC8

With it's current cam (which I'll get you the PN) it carries about 400 lbs of torque from 3500 to 5500. It does require me to slide the clutch a bit more and have a bit more initial timing screwed in than I'd like. I am going to get my wide band sniffer on it this week and see if I can tune around it. Otherwise like I had mentioned, I am going back to the stock LT-1 cam. I've built this combination before in a fuel injected 327 and it just plain works!

[napa68]

Originally Posted by John Brown

Here is some good reading on camshaft choice for street driven small blocks.

a-tale-of-two-camshafts-st-louis-ncrs

This is a great article to take note from. One of the fellows who penned this article, I have come to know through the years. There is a good amount of common sense knowledge that avoids the typical magazine camshaft of the week BS.

It explains why these LT-1's just flat scream and have manners at the same time.

I'm sure there are others here that have different opinions (which is fine). This just happens to be mine from a good amount of past experience.

Tim

[Lynn]

JMHO, but if you want a lumpy idle, you don't want an LT-1 camshaft. Just know this; without variable valve timing or computer controlled opening, there is no "best of both worlds" once you go to the lumpy idle. You may have issues with vac for power brakes. The engine is finnicky, and more difficult to tune. But, it that is what you have your heart set on, your car, your money.

Personally, I would go with a roller. Anything radical will require pretty stiff springs. With a flat tappet cam, you will need to break it in with just the outer springs, then pull the springs and install the inners as well. Not that big of a deal if you have an engine test run stand, but a PIA to do it with the engine in the car; especially if you are working on a freshly painted car. Pucker factor increases significantly. Even then, and even with EDM lifters, you STILL run a chance of wiping a cam lobe, especially if it sits for long periods of time.

[frankk]

Lynn and Napa all really good points. I have a numbers vehicle that gets shielded use, by that I mean its always shielded from the weather and abusive type usage. However I am not afraid to use the 327 motors I have and the lumpy idle is a huge turnon for me. I know whatever I build there is still ricers and new muscle that will blow me away, but at the end of the day when I back the car into the driveway and listen to that idle it will all be worth it

[LT1vette]

Originally Posted by napa68

This is a great article to take note from. One of the fellows who penned this article, I have come to know through the years. There is a good amount of common sense knowledge that avoids the typical magazine camshaft of the week BS.

It explains why these LT-1's just flat scream and have manners at the same time.

I'm sure there are others here that have different opinions (which is fine). This just happens to be mine from a good amount of past experience.

Tim

Originally Posted by Lynn

JMHO, but if you want a lumpy idle, you don't want an LT-1 camshaft. Just know this; without variable valve timing or computer controlled opening, there is no "best of both worlds" once you go to the lumpy idle. You may have issues with vac for power brakes. The engine is finnicky, and more difficult to tune. But, it that is what you have your heart set on, your car, your money.

Personally, I would go with a roller. Anything radical will require pretty stiff springs. With a flat tappet cam, you will need to break it in with just the outer springs, then pull the springs and install the inners as well. Not that big of a deal if you have an engine test run stand, but a PIA to do it with the engine in the car; especially if you are working on a freshly painted car. Pucker factor increases significantly. Even then, and even with EDM lifters, you STILL run a chance of wiping a cam lobe, especially if it sits for long periods of time.

A little info on one of the authors, Duke Williams. I have met him and had numerous emails back and forth with him when I built my LT1.
He worked for Chevrolet and with Zora Duntov. He knows the "LT1 cam" like no one else. He has valve timing set up specs that changed the characteristics of this cam, he KNEW how to set it up to get it to work. A humble but extremely knowledgeable man.

As for the vacuum problem..... What problem?? There was not another model built that needed more vacuum than a Corvette. Power brakes, vacuum headlight doors, vacuum windshield door, distributor.... If you had a lack of vacuum it was because of leaks in those specific systems, not the camshaft....

[NorCam]

I'm going to wade in here with a couple of cam suggestions for someone who wants a somewhat lumpy idle, but still wants to retain some good driving characteristics. The first is an updated solid camshaft which serves as a great replacement cam for any small block from the 302 right up to a fresh LT1. Sounds pretty stout at idle, but still retains decent street manners with enough vacuum to run power brakes. At .500' lift with 247/254 duration on a 112 LSA, it has a tight lash (.012) with modern ramps. Best suited to a 4-spd car with some gearing, it's designed to run from 2300 up 6900 rpm. I found it was better from about 2800 up with a wide ratio stick running 373's. I recently recommended this cam to another sYc member and his 302 dyno'd at 365hp with this cam profile. In a stock LT1 build, I would imagine that the same gain would be appreciated netting close to 400hp with the additional cubes.

Comp Cams Nostalgia Plus 12-673-4 Mechanical Cam

Idling in my green Z/28 with freshly built DZ 302 (Fast Idle)

Now...if you're looking for a very driveable cam with excellent street manners, a lumpy idle, and something that will garner some attention from light to light, here's another cam that Dave @ Crower recommended to me a few years ago and I am so impressed with. I ran this Crower 00471 Hydraulic Roller in a mildly built 350 LT1 with pop-up pistons and freshened 462 heads that had a little bowl blending done. The result was a great lumpy idle and a cam that worked really really well between 2400-6500 rpm. Sounded nasty at idle, pulled real strong through all gears, and was very smooth with great torque through the entire rpm range. The bonus with this roller cam was less valve train maintenance and the $hit assed grin I always wore while driving this one. The cam was so good, I am considering building another 302 and might run this cam again. It doesn't run up into the 7K range, but more than makes up in the 3500 to 6500 range.

Crower 00471 Hydraulic Roller Camshaft (Perf Level 4) 2400 to 6500 rpm

Idling away in a freshly built 350 LT1 (68 Camaro Build)

And here it is on a nice 3 gear pull while I was breaking in the new motor.

[NorCam]

On that Hydraulic roller motor, I ran the cast iron 462 heads with Comp 1.50 roller rockers, the short version of Crower poly locks, and the heads were easily cut for the Crower valve springs. They do fit under the finned aluminum Edelbrock covers very nicely, and also fit under the GM finned Z/28 covers but I did run the double-thick cork gaskets to get the right clearance. (gaskets can be seen in the pics below)

Such a great combo, and one of the biggest Hyd Roller profiles you will find. I'm sure those last 2 videos are a true testament to how well-mannered that cam really was at low speed, and how well it pulls up top. Made great vacuum for the power brakes and vacuum-powered headlights too. Great Camshaft!

[Zman1969]

whoa! hold up on that car wash boys! I didn't ask for a lumpy idle.
I want a cam that will allow this to run and not detonate it self to death being a 10.5-11:1 engine
the heads I did some mild bowl blending on no hogging out, the machinist that did assembly asked who ported them because he liked what he saw, never had flow tested but these are just street heads

If roller will fit under the Z28 valve covers I'm all ears

[napa68]

This thread did take a life of it's own, and I'm guilty of losing sight of the OP. Having said that, I believe the LT-1 cam will need a splash of race fuel above pump premium to live at 11:1 (assuming normal head gaskets, timing curve, and carb calibrations). At 10.5:1, you may just get by.

Sorry for adding to the confusion!
Tim