Another pushrod length ?
Thread Starter
11 Second Club
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Joined: Nov 2004
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From: Thornton, CO
Another pushrod length ? Currently running 7.300" and I believe they are too short. But not by much.
Been fighting with my adjustable pushrod for weeks it seems. I get numbers all over the place.
Most seem to be close to this math, but some are WAY off.
Seems the adjustable just spins instead of adjusting.
Stock rockers.
Running Lunati/Morel lifters. I want preload around .027"
Heads milled .020".
Gasket is a cometic .045"
So, from a proper .100" preload on the stock lifters running a 7.425" pushrod, I did some math. (smaller base circle gave it the extra .025")
Take that pushrod size, lose .073" for the difference in proper preload, another -.020" for milling of heads, and anther .009" for the gasket difference.
7.325 work here??
What are guys with Morel lifters running for a pushrod?? What size and how did you pick out that size?
I know...I know...measure. I have been trying. About had it with that though.
Been fighting with my adjustable pushrod for weeks it seems. I get numbers all over the place.
Most seem to be close to this math, but some are WAY off.
Seems the adjustable just spins instead of adjusting.
Stock rockers.
Running Lunati/Morel lifters. I want preload around .027"
Heads milled .020".
Gasket is a cometic .045"
So, from a proper .100" preload on the stock lifters running a 7.425" pushrod, I did some math. (smaller base circle gave it the extra .025")
Take that pushrod size, lose .073" for the difference in proper preload, another -.020" for milling of heads, and anther .009" for the gasket difference.
7.325 work here??
What are guys with Morel lifters running for a pushrod?? What size and how did you pick out that size?
I know...I know...measure. I have been trying. About had it with that though.
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
I usually just set checker at 0 lash, measure that with a caliper (digital) and I add my preload by calculation.
Unfortunately with stock non adjustable rockers, it is more difficult to reach desired number, because p-rod length available are in .025 increaments. So one always end up over or under (we pick under).
In my recent built I started with reverse pshycology. I said well, I have these p-rods, now what gasket /mill combo can I run to get me desired preload (keeping in mind SCR/DCR). I know this seems weird but it worked since i was doing a whole rebuilt.
Unfortunately with stock non adjustable rockers, it is more difficult to reach desired number, because p-rod length available are in .025 increaments. So one always end up over or under (we pick under).
In my recent built I started with reverse pshycology. I said well, I have these p-rods, now what gasket /mill combo can I run to get me desired preload (keeping in mind SCR/DCR). I know this seems weird but it worked since i was doing a whole rebuilt.
PM me for a source on pushrods in .005 increments. And I run a 7.300 pushrod with my Morels, however my setup has nothing to do with yours, it's what I needed when I measured.
Thread Starter
11 Second Club
iTrader: (9)
Joined: Nov 2004
Posts: 1,360
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From: Thornton, CO
Pretty sure I can get whatever size I need from a sponsor. Down to the .001" if I recall.
If I need to though, I will PM you.
Without measuring though....
Guess I will go with the 7.325 and see what happens. By my math, those should be closer than I am now.
If I need to though, I will PM you.
Without measuring though....
Guess I will go with the 7.325 and see what happens. By my math, those should be closer than I am now.
If your lifters are pumped up you can tighten your rockerarm bolt from zero lash, the point where the pushrod stops turning when twisted with your fingers, to 22 ft lbs torque. You should get somewhere between about 3/4 and 1 1/2 turns. The adjustable PR will let you vary the length. Make sure the tip of the rocker arm wipes the center of the valve. A felt tip pen on top of the valve stem will verify the correct wipe.
I just took apart the car i just bought for oil reasons and i was checkin the pr's tonight there was 7.400in there aftermarket and it hsa ran fine...but i used the pr length tool and i struggled but i set the rocker at 22 ft-lbs or close then adjusted the tool at 7.25 it was almost at zero lash and 7.3 was too much it was tight b4 i hit the tightness on the rocker...so i assume 7.35 will be about perfect right? 7.27 or.28 roughly plus .08? And why switch if it ran fine...i did turn the crank and the rocker seemed to angle a little too much with 7.4 and was better with 7.35 but 7.3 bearly moved...u dont wanna go t short either...
You should have around 1 full turn from where you can't twist the PR with your fingers and 22ft lbs torque. Then you need to swipe the tip of the rocker arm to make sure the geometry is OK.
