Deeavi

iTrader: (16)

I am installing tthe Comp Cams Pro Magnum Rockers and I am not sure about the preload. All other sbc engines usually take 1/2 to 3/4 turn after the slack is out and pusrod is ready to move.

There are no instructions, but on the Crane web site the Crane says that the adjustable rockers take 2 full turns of the adjusting nut for proper preload! I am asuming that is correct, but I know what assuming can do! Anyone else ever installed the adjustable LS1 rockers?

Deeavi

iTrader: (16)

Well, I thought someone may have done this before. Maybe they are not on the board tonight! I went out and figured it out. I adjusted them by the crane method and it seems to be right on, so I will run with that. 2 full turns cold after lifters bleed down. It was easy on mine because it hasn't been run yet, so I didn't have to worry about bleed down.

Beast96Z

iTrader: (21)

Seems like alot to me. Usaully it is around 1/2 to 3/4 of a turn. I prefer 1/4, but that's just me. 2 full turns on a unprimed lifter seems like a whole lot.

Deeavi

iTrader: (16)

Yes I thought the same thing! But crane says that is the way it is supposed to be! I noticed there is still a good bit room to go before the lifter bottoms out! I guess these engines are designed that way. I am like you though, it seems like a lot to me!

MT POKT

iTrader: (10)

When I re-installed my Pro-Mags, I didn't like the idea of 2 turns. I called Comp and the guy I spoke to about **** when I said 2 turns. He told me 1/2 to 3/4 turn to pre-load. I made sure he knew I was working on an LS1. He explained that the roller lifters need less pre load than flat tappets. I expected it to be the opposit. There was no more valvetrain noise either.
I installed 1.6 Crane adjustables on our 355 SBC and the instructions were 1/4 to 3/4 turn on them also, and they are flat tappet lifters. None the less, no problems with either motor.

Beast96Z

iTrader: (21)

Deeavi, the lifters are the same as any earlier hydro roller lifters. There is no reason why they would need any more or lees load. I would readjust and you'll prolly pick up a little power.

QuietTahoe

Hydraulic roller lifters are unlike flat tappet lifters. There is a pressure angle on the lifter caused by the way it rides on the cam lobe. For some reason this has an effect on performance from preload. For max performance on flat tappets you want to run 0 to maybe 1/4 turn preload. Hydraulic rollers require about .060"-.080" preload for max performance. This is about 1 1/2 to 2 turns with Chevrolets. The amount depends on the pitch of the adjuster. I have tried this on several different engines: SBC, LS1, BBC,BBF,SBF and they all act the same way. The extra preload on the hydraulic rollers maximizes HP and extends the usable RPm range 300-500RPM. Do what you want, but I like maximum performance from my rides. As the old TV ad used to say "Try it, You'll like it". Have a good day!

Deeavi

iTrader: (16)

Well I figured Crane would not state the fact if they did not know what they were doing. I did install thier lifters.

"IMPORTANT LS1 VALVE ADJUSTING TIPS
When adjusting the lifter preload on a hydraulic roller camshaft,
special care must be taken to account for lifter bleed down. Install
the rocker arms on the studs and tighten the adjusting nuts to
achieve zero lash (with no preload and no pressure on the valves).
Be sure the setscrew in the adjusting nut does not contact the stud.
Now, rotate the crankshaft one full turn and adjust any loose rocker
arms to zero lash. Rotate crankshaft again one full turn and
adjust any loose rocker arms to zero lash.
Do not rotate the crankshaft during the remaining procedure.
Allow lifters to bleed down for 30 minutes. Adjust any loose rocker
arms to zero lash. Now, tighten each rocker arm adjusting nut
¼ turn. Allow the lifters to bleed down for 15 minutes. Repeat this
procedure seven more times for a total of two full turns. Be sure to
allow 15 minutes bleed down time after each ¼ turn.
The lifters now have the proper preload. While holding the adjusting
nut with a wrench, carefully tighten the setscrew in the adjusting
nut of each rocker arm. Do not rotate the nut during this
process. Allow another 30 minutes bleed down time for this final
setting."

Beast96Z

iTrader: (21)

Don't know why, but I've never heard that one before. First time for everything I guess. Deffinatlly don't try it on some comp R's.

eallanboggs

iTrader: (1)

Can you imagine the cost of doing that procedure then waiting 30 min and then doing it 7 more times and waiting 15 min between each adjustment at the dealership rate of $65.00 per hour. Sounds a little expensive to me. If you stop at ZERO lash there is little or no preload at that point so not much bleed down will occur. If you use stock lifters your supposed to go about 1/2 turn past ZERO lash (pushrod is beginning to resist rotation). With R lifters you stop right at ZERO then lock down the set screw while holding the polylock stationary.

FASTONE

Make sure when you adjust the rocker that the lifter is on the heel of the cam(no lift)I still believe 1/2 to 3/4 turns is plenty but I would be inclined to go with manufacturer of the lifters, don't forget that changing the preload changes your rockerarm geometry be sure to check roller movement over tip of the valve.by the way you dont have wait to make full adjustment as the lifter will go down,this is alot easier with valley cover off if you can, as you can see the cam.

Deeavi

iTrader: (16)

Thanks, Well we will see shortly. I am getting close to start-up. I had to modify my coolant pipe to work with the weiand intake, then we have to put the intake/thottle body on and plug everything in. Hopefully this afternoon I will have it running!