rocker adj. screw , how many threads

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74fldart

74fldart

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hi fellas, im trying to get a set of adjustable rocker arms set up on a 383. ive got some heads that have been milled .060 and when i put it all together the rocker adjuster screws dont have any threads showing . i think ive seen posts that say there should be at least 2 threads showing . if thats the case i guess im going to need shorter pushrods. anybody got any advice?
 
If the heads were milled your pushrods got effectively shorter. You want somewhere around 0-2 threads showing, no more, no less than full thread engagement. If this is for use with hydraulic lifters you need to have the proper preload figure too.
 
I have been chasing pushrod lengths around lately myself. No-one said which end the 3 threads should be exposed on. With only 2 threads exposed on the ball end, the cups on the pushrod hit the rocker arm. I chose to screw the adjusting nuts down to within 4 turns. There's plenty of adjustment left and the the ball and cup aren't fighting with the rocker body. I shimmed the rocker shaft up to re-align the tip with the valve stem. Milling heads, grinding seats, and replacing valves really messes with rocker geometry.

engine 174.jpg
 
Just as moper said. My instructions with crane adjustables calls for 2-3 threads showing on the pushod or bottom side what ever you want to call it.

sorry, just saw you are using the stock arms and adjusters. My info is useless with stock stuff. With the stock ones I believe as long as your not bottoming the threads in the arm your good. As long as your hydraulic lifter preload is good.

ps. That pic actually looks good for adjustment if everything else is good.
 
You also want to make sure if you have to buy them that you get the right cups... 3/8 pushrods might have a larger radius and that might be why the cups hit the rockers.
 
i dont have any threads showing on the pushrod side of the arm and i have yet to check to see how the rocker pad (these are crane iron rockers without the roller tip) touches the valve thru its full movement . when i did this a few years ago i had a pair of heads milled .055 but i used stock rockers and .030 shims for the shafts and it worked ok.

this time i bought a set of the ball and cup pushrods for the adjustable rockers and they were supposed to be stock length but i guess they are too long now.
 
My original pushrods are 5/16" and so are the rocker balls. My replacement pushrods are Comp #7692 and are 5/16" also. The cups are the same size between the two. I don't remember how many threads were exposed on the adjusters with my stock heads and original valvetrain. When I measured for pushrods the first time I didn't have enough of the ball end of the rocker adjuster exposed and my pushrod checker has a smaller cup so it looked like clearance wasn't an issue.When I got my pushrods and tried them the cups hit the rocker body because the ball end of the adjuster wasn't out far enough.
After remeasuring and a shorter pushrod no more issues. Mike
 
74fldart said:
hi fellas, im trying to get a set of adjustable rocker arms set up on a 383. ive got some heads that have been milled .060 and when i put it all together the rocker adjuster screws dont have any threads showing . i think ive seen posts that say there should be at least 2 threads showing . if thats the case i guess im going to need shorter pushrods. anybody got any advice?
Click to expand...
1/2 to 1 1/2 threads is what I always go for...you don't want the pushrods to push back and forth..you want them to push up and down...M2C
 
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