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I am installing a retrofit hyd. roller cam in my 383 buildup. I have a question regarding pushrod length. I am using an adjustable length pushrod to check for zero lash and pushrod length at the same time. This has proved to be a bit tricky since you have to sort of "guess" or "feel" whether or not to tighten the rocker nut or to adjust the pushrod length.
So far I am coming up with a pushrod length of about 7.25" inches. I think this is "ballpark" since the length of a oe roller rod is 7.2"
I was wondering if any of you guys have gone through this measuring process with good results? Did you end with with the same length pushrods for retro fit hyd. roller as OE hyd. roller?
fyi: cam is comp 286HR with retrofit hyd. roller lifters. Scorpion 1.5 roller rockers all mount on 7/16" studs in edelbrock RPM alum. heads.
Not sure what stage you are at with the build but I would recommend soaking the bottom section of all the lifters in some engine oil, this will guarantee an adequate oil supply at the wheels on fire-up!
Also no lube is necessary on the lobes, conventional oil is sufficient! Would also prime the short block BEFORE setting any preload on the lifters! This guarantees the plungers are in the correct location to begin.
On a side note what brand lifters are you using? There will be a .200" difference in the final pushrod lengths between certain brands?
Thanks, Gary in N.Y.
P.S. Just one more "tip" if it were being built here, I would "toss" those heavy-weight rockers for some lighter-weight stainless pieces. This is how we set up almost ALL of our 100% stock-appearing builds (photo below)! Stainless rockers today can be had reasonably priced, I would say under $160.00/16 for the 3/8" or 7/16" studs (preferred)!
Last edited by GOSFAST; Dec 15, 2018 at 10:35 AM.
Reason: C
Thanks for all the advice.
Just to be clear, i was suggesting using the new roller lifters with the old cam to measure pushrod length, then installing the new roller cam once it is close to prevent wiping the lube on the cam.
Is there really no special assembly lube needed for a roller cam during break in?
Everywhere i read notes assembly lube; not sure if it is moly lube for flat tappet and something else for roller.
I bought checker springs for the pushrod length measurement, but with it being my first time, i'm expepecting quite a bit of trial and error.
No, that would be a pointless exercise..... The base circle and lobes are different on the old and new cams..... the geometry at the rocker will be different as a result. You'd be wasting your time screwing around with the old cam.
No special assembly lube is required for roller cams and lifters. Regular old motor oil. Soaking the lifters to prelube them is also a good idea to help protect the hydro lifters plunger assembly as you rotate the engine over adjusting the valves. Having the lifter pumped up hard also makes finding zero lash easier for some people.
Don't worry about wiping the lube off the cam....Once you prime the oil system before start up, so much oil is going to flood the cam lobes via the lifter bores..... lets just say it'll be well lubed.
Will
Not sure what stage you are at with the build but I would recommend soaking the bottom section of all the lifters in some engine oil, this will guarantee an adequate oil supply at the wheels on fire-up!
Also no lube is necessary on the lobes, conventional oil is sufficient! Would also prime the short block BEFORE setting any preload on the lifters! This guarantees the plungers are in the correct location to begin.
On a side note what brand lifters are you using? There will be a .200" difference in the final pushrod lengths between certain brands?
Thanks, Gary in N.Y.
P.S. Just one more "tip" if it were being built here, I would "toss" those heavy-weight rockers for some lighter-weight stainless pieces. This is how we set up almost ALL of our 100% stock-appearing builds (photo below)! Stainless rockers today can be had reasonably priced, I would say under $160.00/16 for the 3/8" or 7/16" studs (preferred)!
Thanks for the advice on soaking the lifters. I have heard about this in the past, and I am planning on doing this once I get to this step.
It makes me rest easy hearing many have not used assembly lube on roller cams, but my cam and lifter kit came with some, so I think ill put some on there anyway. I've heard about clogging up the roller lifters with gunk, but i figure if i only put it on sparingly, then it should only benefit the break-in process.
Where are you getting full roller rockers for only $160.00? I bought the comp ultra pro magnum rockers, which are stainless, and are probably overkill, but I am tapped and installed screw in studs myself, so I want to have as much help with valve side loading as possible.
No, that would be a pointless exercise..... The base circle and lobes are different on the old and new cams..... the geometry at the rocker will be different as a result. You'd be wasting your time screwing around with the old cam.
No special assembly lube is required for roller cams and lifters. Regular old motor oil. Soaking the lifters to prelube them is also a good idea to help protect the hydro lifters plunger assembly as you rotate the engine over adjusting the valves. Having the lifter pumped up hard also makes finding zero lash easier for some people.
Don't worry about wiping the lube off the cam....Once you prime the oil system before start up, so much oil is going to flood the cam lobes via the lifter bores..... lets just say it'll be well lubed.
Will
Thanks for the advice, and I appreciate the direct and clear answer. It makes sense, now that i think about the cam base circle.
Lifter pump up was the wrong term I used in my description above but you get the idea. Also, I did soak my roller lifters in oil the night before I started the pushrod checker procedure as well, back in 2014 during the motor build.
I just checked my notes from Howards on the lifter pre load height and I was told for their lifters about .030-.060. I went with .050..........Turned out perfectly...........
Last edited by jb78L-82; Dec 17, 2018 at 12:54 PM.
Know its an old post but wondering where is roker arm center line on non roller rocker arm drawn for pushrod measurements. Have Corvette L76 327 with Hyd Roller comp cam 12-601-8 with comp cam rocker 181-1049, Comp roller lifters 853-16. Was using 7635 pushrods until studs pulled up some so returned to engine builder for 134-7101ARP screw in studs. Was told steps machined down on head for new studs. Problem mow rocker arm nuts bottom out on threads of studs with some valve lash remaining. Appears either pushrods are too short or stud steps were not machined down enough. The 7635 pushrods are 7.150" and several post suggest the longer 7609-16 which are 7.30". A few even call for 7637-16- 7.35" and 7638-16 - 7638-16. Any suggestions are appreciated and just want right parts that work installed. Thanks for your help in advance.
Know its an old post but wondering where is roker arm center line on non roller rocker arm drawn for pushrod measurements. Have Corvette L76 327 with Hyd Roller comp cam 12-601-8 with comp cam rocker 181-1049, Comp roller lifters 853-16. Was using 7635 pushrods until studs pulled up some so returned to engine builder for 134-7101ARP screw in studs. Was told steps machined down on head for new studs. Problem mow rocker arm nuts bottom out on threads of studs with some valve lash remaining. Appears either pushrods are too short or stud steps were not machined down enough. The 7635 pushrods are 7.150" and several post suggest the longer 7609-16 which are 7.30". A few even call for 7637-16- 7.35" and 7638-16 - 7638-16. Any suggestions are appreciated and just want right parts that work installed. Thanks for your help in advance.
It would really be best to start a new thread here asking these questions but when I measured for my pushrods I bought an adjustable length pushrod measuring tool and a light spring to install on the valve for measuring purposes and colored the end of a valve where the roller rides with a blue sharpie then I adjusted the length the length until the roller wore away the blue mark in the center section of the end of the valve. due to gasket thickeness head casting differences , lifter height and even the cam these numbers vary from combo to combo but you should be able to see now if the roller wear pattern on the end of the valve is centered or towards the top or bottom of the valve tip. if its towards the bottom your rods are too long towards the top, and they are too short.
Know its an old post but wondering where is roker arm center line on non roller rocker arm drawn for pushrod measurements. Have Corvette L76 327 with Hyd Roller comp cam 12-601-8 with comp cam rocker 181-1049, Comp roller lifters 853-16. Was using 7635 pushrods until studs pulled up some so returned to engine builder for 134-7101ARP screw in studs. Was told steps machined down on head for new studs. Problem mow rocker arm nuts bottom out on threads of studs with some valve lash remaining. Appears either pushrods are too short or stud steps were not machined down enough. The 7635 pushrods are 7.150" and several post suggest the longer 7609-16 which are 7.30". A few even call for 7637-16- 7.35" and 7638-16 - 7638-16. Any suggestions are appreciated and just want right parts that work installed. Thanks for your help in advance.
How much valve lash is remaining? I agree it is possible the stud mount bosses may not have been adequately machined. If you have say, .100" valve lash to take up, you will need a pushrod that is .067" longer to take up the excess lash. (.100/1.5 for a 1.5 ratio rocker) Plus you need to add some to ensure you have a little adjustment left without bottoming out the nut again. On top of that, you still need to make sure the roller is centered on the valve stem. Get a pushrod length checker, set everything up so it works, and see if you can get a pushrod the correct length. No one can tell you what that is going to be.
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