Push rods with GN1's

[boostmaster]

Can you run stock push rods with GN1's or do you have to run custom length push rods?

 

[bison]

It's up to the assembler to check the pushrod length. I wouldn't run stock pushrods with anything more than 260lbs over the nose. Use an adjustable to determine the needed length and order a set of chrome moly pushrods.

 

[boostmaster]

It's up to the assembler to check the pushrod length. I wouldn't run stock pushrods with anything more than 260lbs over the nose. Use an adjustable to determine the needed length and order a set of chrome moly pushrods.

Thanks for the reply, these will be on a flat tappet hydraulic set up with 1.65 Harland sharp rockers. What is the correct procedure for checking push rod length with adjustable rockers? I have a push rod length checker I bought today. Do I bolt the stock rockers back on and check for correct length then reinstall the rollers?

Thanks, Pete

 

[pacecarta]

harlands dont have a big window for adjustment . they only allow a .050" window of adjustment , flush to one thread out looking at adjuster cup from underside

set the adjuster on the harland rocker to flush (underside) ,
rotate engine until lifters are on base of cam
install checker tool (adjustable pushrod set to shortest length )
install rocker assembly and torque down
adjust pushrod out until at zero preload (just after you dont have any lash )
adjust pushrod out additional 1/2 -3/4 turn for your desired lifter preload (1/2 turn out would be .025")

good idea to check intake and exhaust on a couple cylinders and on both heads as they could vary

 

[pmoore4321]

harlands dont have a big window for adjustment . they only allow a .050" window of adjustment , flush to one thread out looking at adjuster cup from underside

set the adjuster on the harland rocker to flush (underside) ,
rotate engine until lifters are on base of cam
install checker tool (adjustable pushrod set to shortest length )
install rocker assembly and torque down
adjust pushrod out until at zero preload (just after you dont have any lash )
adjust pushrod out additional 1/2 -3/4 turn for your desired lifter preload (1/2 turn out would be .025")

good idea to check intake and exhaust on a couple cylinders and on both heads as they could vary

I thought the HS rockers were supposed to be set between 2 and 3 threads showing from the bottom.

 

[pacecarta]

I thought the HS rockers were supposed to be set between 2 and 3 threads showing from the bottom.

from their website
" Pushrod length adjuster should not exceed more than 2 threads out of the bottom of the rocker arm. "

 

[pmoore4321]

Must be different recommendations for the TA and Harland Sharps? I had the same set of HS rockers/cam/lifters in my previous engine adjusted like you suggested with about one thread showing. That engine had no valve train noise at all. I moved the same valve train to my new engine and it has the "sewing machine" noise. The only thing different is push rod length. I bought shorter pushrods to get the two threads showing like the following from HS suggests.

 

[pacecarta]

boostmaster .. go with the instructions pmoore4321 posted

 

[boostmaster]

boostmaster .. go with the instructions pmoore4321 posted

Well just to be safe I bolted the stock rockers back on and took the measurements from there so I could take the guess work out of rocker adjustment. Anyway I got a measurement of 8.800. I had bought some 8.850 pushrods just in case but luckily I took the measurement because I would have been way too long on the preload.

 

[bison]

Well just to be safe I bolted the stock rockers back on and took the measurements from there so I could take the guess work out of rocker adjustment. Anyway I got a measurement of 8.800. I had bought some 8.850 pushrods just in case but luckily I took the measurement because I would have been way too long on the preload.

So you're running the stock rockers?

 

[boostmaster]

So you're running the stock rockers?

No, going to be running Harland Sharps just took the guess work out of adjustment angle to get a measurement of length first. Now that I know the length I can adjust preload after the new rockers are installed.

 

[bison]

I would have used the rockers I planned on running.

 

[pacecarta]

I would have used the rockers I planned on running.

x 2
wouldnt surprise me to see .100" difference in pushrod length on stock vs roller rocker

 

[boostmaster]

I would have used the rockers I planned on running.

x 2
wouldnt surprise me to see .100" difference in pushrod length on stock vs roller rocker

Thanks for the input, no problem to swap them out and re-measure. It's just 3 bolts away.
But I prefer to use the pushrods set up for the stock rockers just in case I want to swap back. That is as long as the difference is no more than 0.50 in length and doesn't cause a problem with coil bind or anything that would give me flexibility to switch between the two. That was my thought, I don't know if that thinking is correct or not but I'm sure someone will let me know if I'm way off base here.

 

[bison]

Thanks for the input, no problem to swap them out and re-measure. It's just 3 bolts away.
But I prefer to use the pushrods set up for the stock rockers just in case I want to swap back. That is as long as the difference is no more than 0.50 in length and doesn't cause a problem with coil bind or anything that would give me flexibility to switch between the two. That was my thought, I don't know if that thinking is correct or not but I'm sure someone will let me know if I'm way off base here.

It's very possible you need 2 sets of pushrods. Coil bind isnt caused by pushrod length.

 

[87_we4]

Why would you want to go back to stock rockers?

 

[boostmaster]

It's very possible you need 2 sets of pushrods. Coil bind isnt caused by pushrod length.

Damn how did I know you would say that!! But on the bright side you didn't say that what I proposed was impossible.

 

[boostmaster]

Why would you want to go back to stock rockers?

I have 2 cars and only one set of roller rockers. One car ported irons and the other GN1's. I think the irons may need the help more than the GN1's. Hey but that's just my thoughts. I'm running a flat tappet hydraulic cam so rollers aren't going to make or break me performance wise with GN1's.

 

[boostmaster]

Well put the rollers back on and re-measured. With rollers on the length is exactly 8.850 with the pushrod adjuster at zero adjustment so that gives me room to go with my original plan of running 8.810" pushrods and give me the ability to run my choice of rockers. Stock or the rollers.

 

[Mike Licht]

I have 2 cars and only one set of roller rockers. One car ported irons and the other GN1's. I think the irons may need the help more than the GN1's. Hey but that's just my thoughts. I'm running a flat tappet hydraulic cam so rollers aren't going to make or break me performance wise with GN1's.

iron heads and Aluminum GN1's use different rocker arms. You cannot change them back and forth
Mike