Cams

[L31MaxExpress]

Gone up a few bucks, but this is how you get around low idle vacuum, tie this to a relay that gets a signal from the brake light switch. When you are on the brakes, the pump runs. I use a 3/8 check valve between the engine and a T-this off the 2nd leg of the T and the 3rd leg of the T goes into the OEM check valve on the booster. If the pump were to fail you would atleast get some assist on the booster from the engine. Hella claims they are not exaclty meant as a stand alone brake vacuum pump but they work very well setup as I mentioned. It is more of a secondary supply to create more vacuum than the engine alone can when setup the way I mentioned. Engine pulls what it can, then the vacuum pump pulls the rest, sealing off the vacuum line to the engine via the check valve.

ACDelco 20939309 ACDelco GM Genuine Parts Power Brake Booster Vacuum Pumps | Summit Racing

Free Shipping - ACDelco GM Genuine Parts Power Brake Booster Vacuum Pumps with qualifying orders of $109. Shop Vacuum Pumps, Street at Summit Racing.

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[VictoryRed]

Gone up a few bucks, but this is how you get around low idle vacuum, tie this to a relay that gets a signal from the brake light switch. When you are on the brakes, the pump runs. I use a 3/8 check valve between the engine and a T-this off the 2nd leg of the T and the 3rd leg of the T goes into the OEM check valve on the booster. If the pump were to fail you would atleast get some assist on the booster from the engine. Hella claims they are not exaclty meant as a stand alone brake vacuum pump but they work very well setup as I mentioned. It is more of a secondary supply to create more vacuum than the engine alone can when setup the way I mentioned. Engine pulls what it can, then the vacuum pump pulls the rest, sealing off the vacuum line to the engine via the check valve.

ACDelco 20939309 ACDelco GM Genuine Parts Power Brake Booster Vacuum Pumps | Summit Racing

Free Shipping - ACDelco GM Genuine Parts Power Brake Booster Vacuum Pumps with qualifying orders of $109. Shop Vacuum Pumps, Street at Summit Racing.

www.summitracing.com

thanks i’ll check it out

 

[VictoryRed]

Look at Comp Cams, been using their 280H for decades.. dang good cam....

is a stock 99 L31 hydraulic roller or flat tappet? i’ve seen mixed results online pretty sure it’s roller but i want to be 100% sure

 

[RacerM95]

If I were you Id look at a Comp 268H or 272H, either one will work stock engine, stock Torque Converter.

 

[Erik the Awful]

one last question what kind of valve springs and retainers would you recommend?

I used GM 12499224 valvesprings - which are the Corvette Z06 LS6 valvesprings. I can't remember where I found the info, but they're about 10% stiffer than the stock Vortec springs. They're no longer available, but Melling sells an LS6 valvespring, and I trust them more than I trust GM.

Melling VS-1623

Free Shipping - Melling VS-1623 with qualifying orders of $109. Shop Valve Springs at Summit Racing.

www.summitracing.com

COMP Cams 787-16 COMP Cams Steel Valve Spring Retainers | Summit Racing

Free Shipping - COMP Cams Steel Valve Spring Retainers with qualifying orders of $109. Shop Valve Spring Retainers at Summit Racing.

www.summitracing.com

If you're running over .500" lift you'll also need to use umbrella valve seals instead of positive seals.

is a stock 99 L31 hydraulic roller or flat tappet? i’ve seen mixed results online pretty sure it’s roller but i want to be 100% sure

If anybody online is saying the L31s came with flat tappets...

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[VictoryRed]

I used GM 12499224 valvesprings - which are the Corvette Z06 LS6 valvesprings. I can't remember where I found the info, but they're about 10% stiffer than the stock Vortec springs. They're no longer available, but Melling sells an LS6 valvespring, and I trust them more than I trust GM.

Melling VS-1623

Free Shipping - Melling VS-1623 with qualifying orders of $109. Shop Valve Springs at Summit Racing.

www.summitracing.com

COMP Cams 787-16 COMP Cams Steel Valve Spring Retainers | Summit Racing

Free Shipping - COMP Cams Steel Valve Spring Retainers with qualifying orders of $109. Shop Valve Spring Retainers at Summit Racing.

www.summitracing.com

If you're running over .500" lift you'll also need to use umbrella valve seals instead of positive seals.


If anybody online is saying the L31s came with flat tappets...

You must be registered for see images attach

Likely won’t be running over 500 lift what would be a good cam to run with this I am okay with the loss of low end torque i just want a nice mean idle without losing too much vacuum i’m guessing something around .480 lift 215-230 ish duration and 112° lsa would be decent?

 

[L31MaxExpress]

XM270HR is as much as I would run and it would really benifit from long tube headers, decent exhaust, volant intake and a properly tuned 0411 along with a good 2,500 rpm converter.

The only real difference between the custom cam I have in my 383 and the cam I mentioned above were changes made because I was trying to tame down the valvetrain noise and tightened the LSA to make more midrange power.

 

[VictoryRed]

XM270HR is as much as I would run and it would really benifit from long tube headers, decent exhaust, volant intake and a properly tuned 0411 along with a good 2,500 rpm converter.

The only real difference between the custom cam I have in my 383 and the cam I mentioned above were changes made because I was trying to tame down the valvetrain noise and tightened the LSA to make more midrange power.

would this give me plenty of aggressive choppy idle?

 

[VictoryRed]

XM270HR is as much as I would run and it would really benifit from long tube headers, decent exhaust, volant intake and a properly tuned 0411 along with a good 2,500 rpm converter.

The only real difference between the custom cam I have in my 383 and the cam I mentioned above were changes made because I was trying to tame down the valvetrain noise and tightened the LSA to make more midrange power.

What springs and retainers would you recommend for this cam? I was thinking of going with melling ls6 style and comp cams retainers just need a second opinion