jub jub

I'll make this simple...


GM or Comp Rs for an XER cam?

PREDATOR-Z

Anything up to .600 lifts, the stockers will handle that. beyond I would switch to at least Crane (better bleed) or Comp "R".
Of course this is with proper preload and installed specs.

MelloYellow

Gm
.
.

jub jub

One for GM and one for Comps. The very reason I asked this question in the first place. I don't suppose there is hard, raw data out there on this subject?

93Polo

iTrader: (5)

jub jub,

What cam did you get? I'd go GM.

jub jub

Hey Lamar, I talked with you at the posse picnic, didn't I? How have you been? BTW, what heads do you have on the FRC to get those good numers?

I went with a comp XE-R. 226/230 .581/.591 @114. It's very noisy on the valve train but besides that, I believe one of my lifters failed on the ride home from the tuner. Once the engine heats up it clacks like crazy under 3000 rpm. I'm going to check the valves/push rods etc. this weekend to see if maybe something else failed. If it is a lifter, I would like to replace all of them with the best I can buy!

Silverhawk_02TA

I don't know if you messed with the oil pump/pickup tube at all when you did the install, but if you did, maybe you jiggered the o-ring a little on reinstall. If not, you might try this: run the engine until it warms up and the clacking starts. Then shut her down and pull the valve cover. Now, turn the engine by hand until you get a lifter all the way down on the cam's base circle. Then, try to wiggle the corresponding pushrod. Repeat until you hit all the lifters. If you get one or more loose pushrods, then I'd say those lifters are definitely not maintaining good pressure. If everything's tight, you might have a different issue.

Now, I've always heard that XER cams make for a noisy valvetrain. But I have to say that my Torquer, which uses and XER lobe, doesn't sound any noisier to me than the stock valvetrain. Strange. Of course, my duals may just be drowning it out...

jub jub

Thanks for the good advice.

I'll know more for sure after I check it out this weekend!

luv2spd

iTrader: (1)

My Torquer made my valvetrain much louder!

Silverhawk_02TA

Probably the duals, then!

DAPSUPRSLO

iTrader: (14)

Like was indicated before it sounds like you may have a lifter or two that do not have enough pre load on them. When the motor heats up and expands lash maybe being added to the valve train and this is a big no no with hydraulic lifters

Lash=a space between the pushrod and pushrod cup on the rocker arm.

jub jub

What is the proper preload on GM lifters? I've read here between 1-1/2 to 2 turns after the pushrod contacts the rocker. And on LS1howto they recommend less than a turn with Yella Terras.

So much conflicting info.

luv2spd

iTrader: (1)

I think with the stock lifters all that you can do is torque the rockers down to 22 lb/ft.

DAPSUPRSLO

iTrader: (14)

Torque specs are not pre load. The 22 ft-lbs is only to keep the bolt secure in the head. You must achieve the proper preload (the load the lifter sees from zero lash {where the pushrod has resistance} to the amount of turns to reach twenty two foot pounds.

In other words if you need 1 1/2 turns for proper pre load you would screw the rockers down until the pushrod no longer turns completely freely, then you should be able to turn the rocker arm bolt 1 1/2 turns and be at 22 ft-lbs.

jub jub

If your using adjustables, what would pre-load be in thousandths of an inch? I have access to a dial indicator and I might get some adjustables just to play around.

fastbasser

iTrader: (1)

I have been told there are problems with the Comp Rs.. Have not heard what the problems were..What are the rest of you guys using for the larger Over 600 lift) cams?

DAPSUPRSLO

iTrader: (14)

Look around but I believe it would be .008"-.010" cold. Call comp or ask some of the sponsors.