Push Rod Length
Thread Starter
Instructor
Joined: Mar 2002
Posts: 140
Likes: 1
From: east hampton ct
Push Rod Length
Can someone tell me if I have measured for pushrods correctly. I installed a weak coil spring on my valves and using an adjustable pushrod varied its length until I got a wear patttern which was center on the valve tip. I had tighten the rocker until there was just tension on pushrod but did not preload the hydraulic lifter. The pushrod length I came up with is 0.050 shorter than stock. To check that length I installed a stock length rod and the wear pattern was over center on the valve. Does this shorter pushrod length need to be adjusted for the 1/2 turn lifter preload. Am I correct thinking that if you are to be off on pushrod length it is better to be short on the rod rather that long.
Race Director
Joined: Apr 2000
Posts: 17,673
Likes: 199
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Re: Push Rod Length (28buick)
You should be doing it with a solid lifter the same size or you can take a hydraulic lifter apart and fix it so it will not depress. The rocker tip should start at one side of the valve tip and move to the centre at 1/2 lift and end the same distance on the other side as you started with. Never heard anything about being better to err on the short side, could run into retainer/rocker clearance problems if shorter. Hope this helps :D
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Re: Push Rod Length (28buick)
I burned a whole day trying to make those adjustable P-rods work 28buick and without success. Engine really needs to be out of car on engine stand for the adj. checker. Bought a Moroso P-rod length checker and then a Proform to double check. Cheap, easy instructions too and done in 5 min. - painless. :thumbs:
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
Re: Push Rod Length (cardo0)
Your technique was excellent but the process was flawed by not using a solid lifter. I think you might be in the "ballpark" becuse of running a hydraulic lifter motor. You will need to preload the lifter a slight amount (less than 0.050") but seems like your right there. The rocker being centered on the valve tip will increase guide life and decrease friction. I would say you are good to go if you are running a mild cam with less that 0.500" lift, you should be OK on your present length. There are always some compromises made and you seem to be within 0.050" so go ahead, you have done more than most and done an excellent job.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Re: Push Rod Length (Solid LT1)
It's the variation in the cam manufactures base circles that makes for all kinds of pushrod lengths. I'd just call Summit racing and see what they have in the books for -.050 pushrods.
I just looked and Trick flow has 7.750 (-.050) for $84 Which is pretty cheap for heavy wall chromemoly
I just looked and Trick flow has 7.750 (-.050) for $84 Which is pretty cheap for heavy wall chromemoly
