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.

 

you do not have to guess, you check the swept area of the valve stem.

 

I have a brand new set of Comp Cams High Tech 5/16" 7.300 long for SBC. PM if interested. They are brand new in the package. I had +100 valves in the heads so they didn't fit. Do you have to figure for the 1/2 turn lash on the length? These are the recommended pushrods for the retro-fit Comp cams XE 288 HR. The Part # is 7949-16

 

The rocker is centered on the valve stem when looking from the front.

When full depressed the rocker is centered when viewing from the side

I don't know if this is what you are refering to.

 

http://www.compperformancegroupstore...Category_Code= Here is a link to read a description. I will take $100 shipped if yiou need them. My thought was if you establish your geometry at 0 lash, Then when installed you crank it down 1/2 turn past 0 lash, your geometry changes that 1/2 turn. That is why I thought these would give you correct installed and adjusted geometry.7.250 plus 1/2 turn, or 7.300 , comp cams recommended length.

 

Thnaks for the offer Mako, but after some more meaurements it would appear that I am in the same boat as you. When I set my pushrod length to 7.3" and then did the zero lash adjustment I appear to be short on lift leaving .300" of piston to valve clearance and not depressing the valve spring (yes a am using light checking springs) as much as the .560" lift of the cam. I changed the adjustment on the pushrod to 7.4" and it looked like it opened the valve all the way without binding.

After reading on Edelbrocks website, they say to use +.100 longer than stock pushrod when using standard ratio rockers. I wonder if this applies to hyd. rollers as well??

What pushrod did you end up going with??

 

I had to have 7.450 to get correct geometry with Retro roller lifters, Comp cams pro magnum 1.5 rr, zero deck, AFR 195 heads milled .025 with +100 valves and a .039 gasket.

 

I would never use a generic pushrod value given by any manufacturer. Way too many varyables in valve train parts for a common length to work with all. Here is the proper way to check...
http://www.carcraft.com/techarticles...pushrod_length
Eddie

P.S. Hi Kev

 

I bought a hydr. roller lifter from Summit ($8) and took it apart, filled it with shims and reassembled. this lifter is the same as the other 16 lifters but solid because of the shims. It's impossible to check the pushrod length with a hydr. lifter, without oil pressure the lifter will collaps...

I set the adjustable pushrod to 7.300", installed it and tightened the rocker nut to 'zero lash', then cranked the engine (by hand of course, not with starter).



The black stuff on the valve stem is Sharpie (permanent marker), see the wear pattern where the roller tip makes contact ?

 

Well after getting **** and measuring for 3 hrs, I have have decided 7.450" is the best for me as well. The roller tip stays pretty centered with minimal travel and the rocker shaft to pushrod is as close to 90 degrees as I can get. I also checked the lift of the valves using a straight edge and a depth gauge (.001") and came up with just a few thousanths under my ideal .560" lift.

My setup is prebably pretty similar to yours, zero decked block, Performer RPM heads milled .005" with a full competition port/polish/valve job and 7/16" studs with guideplates. Comp 286HR with 853-16 roller lifters. 1.5 scorp. rockers.

Thanks for your help

 

MYBAD79 has an excellent point, I just fell victim to false readings from hyd lifters. I was getting all kinds of crazy stuff I couldn't figure out until I remembered that the lifters collapse if they don't have oil in them. The body rises but the inside doesn't move for quite a distance and it'll give you bad information. Be careful.

Bad79.that's a good idea and good info.

 

I know this is an old thread, but I hate creating new ones when there is good advice in the past.

I am putting a set of vortec heads that were milled down 0.025 on my matching numbers L48 as well as putting in a new Howards retro-roller cam.
To be honest, this will be the first time I have broken in a cam, which is part of the reason I went with a roller cam, and will also be the first time I have measured pushrod length. While I know roller cams are more resistant to damaging the cam during break-in, I want to take all the precautions to ensure the cam has the least amount of wear incurred during the process, and minimal amount of metal particle to flush out.
I am putting all this together right now, but I am planning on using the stock vortec springs for the break in process, then swapping to the permanent stronger valve springs, just to be safe. From the other threads I've read, this may be overkill, but this is a stock bottom end and my first time, so I want to be extra careful. It will also be a lesson learned, so I want to experience it all.

When measuring for pushrod length, do you keep the old cam in the engine until the pushrod length is determined?

It seems like if I install the new roller cam before, then turn the engine over several times tryign to find the right length pushrod, I would be wiping a lot of the moly lube off the cam that is so important for break-in.

Will the length be significantly different?
When I think back to geometry class, I'd imagine the sweep would be a bit bigger since the new roller cam has a bit more lift, but I would think as long as it's centered on the valve tip, it should be the same, no?

Has anyone done a measured pushrod length on the old cam to get it close, then installed the roller cam, then checked again just to be sure?
My thought is hopefully this reduces the number of trial and errors with the new roller cam installed?

 

I just went thru this with a solid roller, .904 diameter lifters. Use the new cam and lifters- Using moly paste on a roller is not needed from what the machine shop I used told me. He said don't even wash the lifters- just wipe the bodies and then oil.
If you use the old cam and lifters, you'll get the geometry for the old cam and lifters.
What you're really looking for is the contact area on the valve stem that the rocker touches- pushrods too long (or too short), and the contact patch is not in the center of the stem. That will also side load the valve and wear the valve guide.

 

Take a look at this. It works. Don't be as worried about centering it...aim for smallest sweep pattern.



JIM

 

So first - IF you have a roller camshaft, there is NO break in. Roller lifters do not need light springs to wear in. Install the proper springs and fire it up.

Second - You should use regular oil on a roller cam and lifters when you assemble it. Moly grease is bad for roller bearings and blocks the little orifices in hyd lifters.

Third - To get an accurate reading for pushrod length & valve train geometry, you either need a roller lifter converted to solid or you can get a very light weight checker springs for like $4 that you temporary assemble on the head and do your "mock up". After you have established the proper pushrod length, then you can assemble the heads with the real springs/retainers. IF you do not do this yes the difference in measured pushrod length will be significant.... Hyd roller lifters have about .150" travel in the plunger/seat and you never know if you fully bottom the lifter out or not because of assembly oil which may or may not have been pushed out/trapped during your check..... Buy the checker springs and do it right.

Fourth - Why would you need the old cam? Throw it in the trash. Your checking valve train geometry because you are changing the camshaft and the new one has different size lobes which change the geometry as well as the new roller lifters which are taller and change the geometry yet again.... Use the new camshaft and new lifters to establish pushrod length.

Link to checker springs on Scummit:

https://www.summitracing.com/ga/part...58-2/overview/

Will

 

 

Not sure why the text got deleted from my previous post when I added the photo but here goes again. The photo is from when I set up the pushrods in my 427 small block. Use the lightweight checker springs. They're cheap. You are looking for the narrowest pattern you can get centered on the tip of the valve stem. I found that as the pattern moved away from the center of the tip, the pattern got wider. The marking compound is just black dry erase marker.

 

Those look pretty wide....

Jim

 

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.

 

Permatex pn 81950 $7-$8 local parts store
This is a time-tested engine assemby lube. Use it for roller cam lobes & roller wheels, block's lifter bores, crankshaft journals, many other things. There're many other that are probably just as good. but this will do it and do it well.


https://shop.advanceautoparts.com/p/...E&gclsrc=aw.ds