FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: Lenz on May 16, 2014, 02:44:15 PM
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I've nosed around enough to see that there's lots of opinion on this topic. The one point that caught my interest was setting the preload deep enough to minimize the oil in the lifters to help keep them from pumping up during higher RPM operation. Seems like 3/4 turn after all free play removal was "supposed" to be good, but I'd appreciate members thoughts and experience in this 8).
The cam is a Comp cams XE274H, .562" /.565" lift and 274/286 degrees duration. Heads are Edelbrock performer RPM's and rockers are roller tip Harland Sharp. I have a push rod length checker, want to mock it up to see what length pushrods I need. I intend to set up the rocker adjustment screws at HS recommended position, 1 to 2 threads showing.
Len
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There is a an interesting article in the summer 2014 edition of the Engine Masters magazine (quarterly spin off of Popular Hot Rodding). I picked mine up last week at the grocery store.
They did dyno testing on a 383 Mopar running different lifters with different preloads, on the same cam. Obviously the 383 Mopar isn't exactly like an FE, but it does use a shaft rocker system. There are too many variables to list that make the testing that was done specific to that exact engine combination, but still a thought provoking read.
Personally for a hydraulic cam, I have always gone 0 lash plus a 1/4 to 1/2 turn on the adjuster.
Brett
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I have run 1/4 to 3/4 on my different motors never really noticed much difference beside a little more or less idle vacumn. The rhoades lifters it made a diff with the bleed down and smoothness at idle They were adjustable between a 1/4 and 1 1/4 as per there tech. Guess it goes down to cam company and cam lift/duration variances diff motors will work better with diff settings.
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Not having the issue, did they find any differences with varying preloads? I'd guess not.
There is a an interesting article in the summer 2014 edition of the Engine Masters magazine (quarterly spin off of Popular Hot Rodding). I picked mine up last week at the grocery store.
They did dyno testing on a 383 Mopar running different lifters with different preloads, on the same cam. Obviously the 383 Mopar isn't exactly like an FE, but it does use a shaft rocker system. There are too many variables to list that make the testing that was done specific to that exact engine combination, but still a thought provoking read.
Personally for a hydraulic cam, I have always gone 0 lash plus a 1/4 to 1/2 turn on the adjuster.
Brett
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Thanks for the input. Seems like there are no "bad" experiences and that it's tough to tell if 1/4 turn or 3/4 turn makes any real difference in a setup like mine. That is what I was looking for, just wanted to see if anyone had any solid reasons for a certain preload setting 8).
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Most hydraulic lifers will have between .080 and .120 of possible travel. Normally works best to put them into the center for normal street use. Means +/- 1 full turn down on an FE where the adjuster is directly on the pushrod. On short travel race hydraulics ( as far as I know exactly one FE set exists...) you set them to be +/-.010 off the bottomed out position - effectively a solid lifter.
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Actually, the did record some variations. Different style hydraulic lifters performed differently under different conditions. They varied from pretty much bottomed out all the way up to loose (lash) with a standard hydraulic. Best pull they recorded was zero lash, zero preload. With the anti-pump ups, they found best power with just a little lash. They also ran the fast bleed down lifters, which improved idle quality.
Again, likely a very engine/combo specific test, but an interesting read nonetheless.
Brett
Not having the issue, did they find any differences with varying preloads? I'd guess not.
There is a an interesting article in the summer 2014 edition of the Engine Masters magazine (quarterly spin off of Popular Hot Rodding). I picked mine up last week at the grocery store.
They did dyno testing on a 383 Mopar running different lifters with different preloads, on the same cam. Obviously the 383 Mopar isn't exactly like an FE, but it does use a shaft rocker system. There are too many variables to list that make the testing that was done specific to that exact engine combination, but still a thought provoking read.
Personally for a hydraulic cam, I have always gone 0 lash plus a 1/4 to 1/2 turn on the adjuster.
Brett
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Try to run the shortest push rod possible... If you can!
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Try to run the shortest push rod possible... If you can!
I'll take that under advisement! I figure pushrod length will pretty much be determined for me by the time I'm done setting everything else up though. HS recommendations, roller travel across the valve stem and lifter preload at about 1 turn without intake manifold interference should spell it out.