jegten

iTrader: (22)

how would i set the preload with the rockers when i am using the stock rocker arms? and torquing them to 22lbs?

moeZ28

iTrader: (7)

I have Comp R lifters with stock rocker arms...0.020" preload and never had a problem with them. My car is very quiet compared to most that sound like sewing machines.

1997bird

iTrader: (2)

Yeah I have seen that done and also seen the lifter's come apart too. Just stay on top of your valve spring pressure's, otherwise if you go to valve float so does the lifter. Which usually breaks the top retainer of the lifter and you start having bent pushrods and a poor running engine.

warp_6

iTrader: (2)

It would be better to use adjustable rockers. I guess you could add .025 to your zero lash push rod length (zero lash w/ checker 7.350) + .025 = 7.375 new push rod length, but I wouldn't go anymore than that. That still is much more pre-load than they call for, but some are running .025 -.050. and aren't having any problems. If you are going to try to apply the .002-.004 pre-load with a push rod I don't see it happening (zero lash w/checker 7.350) + .003 = 7.353 new length.

jegten

iTrader: (22)

hey, warp,

thanks for this info.
i am wanting to keep my stock rockers, and still be able to use the comp r.
i see how the small preload might not have an effect in figuring the length of pr. any suggestions?
thanks

PS: i guess i can always sell these lifters and get the 850s.

warp_6

iTrader: (2)

I would use adjustable rockers if you are going to use the comp R's. That way you can cotrol precisly how much pre-load your lifters get. Or like you say sell the R's, and get something else. Myself I am setting up some R's right now. I just ordered the PR's tonight. I am using comp shaft mount adj. rockers. If you do go the adj. rocker route. You will need to clearance your valve covers. It seems every mod you make creats some other problem, or something else that needs to be worked out. Putting out fires.

brad8266

iTrader: (23)

Why are you guys telling him to preload those lifters to .025 when Comp says to preload them to .002-.004? Use the checker and just order a custom rod if need be.

1997bird

iTrader: (2)

I don't know, but I'm with you on the preload.

jegten

iTrader: (22)

thanks, guys.

i guess i got a little insecure after seeing the almost "negligible" effect the .002-.004 would have in the formula to figure out the pr length. so, i suppose i would do the warm up thing, go back to zero lash, add the .003 to that new zero lash in the formula, and order my new pr, if need be. right?

i really appreciate this.

hey, brad, like your numbers a lot, what is your set up?

brad8266

iTrader: (23)

yeah thats the right way to do it.
Heres my setup https://ls1tech.com/forums/dynamometer-results-comparisons/685582-dynoed-my-new-head-cam-forged-motor-today.html

BOWTIE

Because it would take a month of sundays to try and get the preload to .002-.004 by using different length pushrods alone... The one guy mentioned he is running them at .025 with out a problem. Granted it is not correct for that style lifter, but he is saying it has worked for him so far. The only way to use the Comp R correctly is to go with an adjustable valvetrain. As mentyioned in my previous post which you may not have understood, off the shelf aftermarket pushrods do not come in any length (i.e. you can not get a 7.356 pushrod from one of our vendors, you might be able to get a 7.350 or a 7.375 but that is outside the .002-.004 range). You could get that size pushrod custom made, but the odds are it would not be the correct length for all of the valves, as the valve set up heights, block deck heights, and even block squareness from front to back will most likely vary by more than .002-.004, the preload he is trying to accomplish. The simple fact is, if he wants to use the Comp R's correctly, he needs an adjustable valvetrain, otherwise he is better off getting rid of them and going with either the 850, a set of stock lifters, or the new Caddy racing lifters.

brad8266

iTrader: (23)

Yeah it may not be a problem now, but by running 6 times the recommended preload those lifters will collapse and fail much earlier than they would if they were preloaded properly. The excuse that its ok because they work now is retarded.

Its simple to acheive proper preload by using different size PR's alone. You just use a PR checking tool and measure zero lash and then add preload and thats what size PR you need. It takes like 5 minutes to do, where do you get these times from.

So what about the variances, they are there regardless so you might as well get your parts ordered as close as possible to what they should be. And even if you did check each lifter for its individual proper PR length it would take like what an hour? Thats not much time to get it right the first time.

BOWTIE

With a conventional hydraulic lifter "as close as possible" is fine, with a Comp R or solid lifter it is not. Why do you think the first line in Comp Cams requirement for these lifters is that you must have an adjustable valvetrain for proper use of these lifters.

brad8266

iTrader: (23)

Right but you can get it right by having adjustables or just buying the right size rod. Pick which one you want to do. I dont like adjustable rockers so i would just take an extra few minutes and get my exact PR requirements to maintain proper preload. That is the exact purpose of the high speed pushrod checking tool, to get exact zero lash numbers, then all you have to do is add preload to that to get your final PR length to maintain preload.

Kaneman

iTrader: (5)

I have comp R's and I guess the shop that put my motor together did not know not to use stock rockers. My lifters are loud as hell. I order new Cadillac lifters but they are on B/O. I am pretty sure I have 7400 length pushrods in the car now. Would it by wise to go to a 7350 or 7325 until I put my new lifters in? If someone had to guess what would be the best size standard pushrod to use on stock rockers?


Kane

brad8266

iTrader: (23)

What cam, head gasket, head mill?

Kaneman

iTrader: (5)

Stock 6.0 heads on an Iron block 408 not sure on the thickness of the head gaskets. It is a small cam 220 224 581 581 114 lsa. I will see if I can get a pushrod measurer I was just trying to get something close. I realize there are so many variables.

Thanks,

Kane

Kaneman

iTrader: (5)

I found the thickness of my head gasket .040. I found all my paper work so if you need anything else let me know.

Kane