last year I built re-built the 390 in my 75 truck. The valve seats were hammered so I went with Edelbrock alum. heads and Harland Sharp roller rockers. We had to get special length push rods and since I'am limited in my knowledge I had the machinest mess with the valve train geometry. I put approx. 1000 miles on the engine breaking it in and it seems I always had a ticking sound coming from the valve train, which got worse one day. I pulled the valve covers and found a broken push rod. I replaced and checked all of the push rods, put the valve train back together, pumped up the lifters and while visually inspecting everything it looks like the push rods on a couple of the cylinders are at an angle to the rockers. While I don't have much knowledge in this area it seems like I remember the stock rocker arms are much happier with the push rods. I had some extra cash at the time and thought I was doing some thing cool but now I'am thinking what my Dad would of told me to do. After all this rambling my question is: If I go back with stock rocker arms and push rods will it be stock even with the after market heads? Thanks for any help. I haven't messed with the engine for over a year and its time to get the beast up and running again.

 

this may be of some interest to you.. I'm about to dealwith a similar issue and will be looking for some real clear , concise answers before commiting..

http://www.classicglasspars.com/inde...d=4574&catid=7

BOL.. to both of us LOL

 

I understand exactly what he is saying the stumper is how to apply it with a non adjustable assembly/Hyd lifters.. pushrods ? ok but the generic scenario was about .030, with 3-4 with a .060 installed height.. and this is from the spring seat..if the valve clearance is desired at .010-.020, kinda throws a fkn monkey wrench in there dont it ..

OK, yep, we're listening, have at it!!

 

Based on the following:

ok after the gauging.. here is what I have

Valve installed height results:

Intake: Shim Exhaust: Shim
(1) 1.8775 - .0575 1.8640 - .0440
(2) 1.8815 - .0615 1.8625 - .0425
(3) 1.8775 - .0575 1.8545 - .0345
(4) 1.8625 - .0425 1.8645 - .0445
(5) 1.8615 - .0415 1.8540 - .0340
(6) 1.8525 - .0325 1.8550 - .0350
(7) 1.8800 - .0600 1.8510 - .0310
(8) 1.8580 - .0380 1.8475 - .0275


I been pondering all afternoon and still have a million reasons to hesitate LOL.

So if I can break this down to my specific scenario that might ease the tension on resolution ????
As posted the installed heights were pretty .030 across the board.. But there was 1,2,3 & 7 intakes with a .060 more or less. Now comes my puzzle shimming a stand for .060/.030 at the same cylinder ???

OK so use a .030 shim across the board

and 1,2,3, & 7 intakes get a new pushrod -.030 ?? I'm really trying here trust me

Yes, NO , Maybe, Kinda Sorta >>>>>> ?????

 

whew! I'm gonna have to get some sleep and then start thinking again. At this point I'm ready to go back to stock and do away with the adjustable roller rockers. Adjustable over hydraulic just seems like too much of a pain.

 

A hydraulic lifter will compensate for approximately .125" of pushrod screw up- that's roughly the distance the plunger in the lifter has.. of course, the closer you have al his the better it is... and the fun begins... LOL

 

I had a similar problem with a set of crane roller rockers which in my understanding are close to the same. I broke 15 pushrods by the end, one finally jumped off the rocker. I was using the cup style pushrod and the problem was at full lift the rocker would pinch the pushrod breaking the cup on the pushrod. Crane told me I would have no problem with the rockers but they were full of bull. Went back with the adjustable iron rockers and no more problems.

 

thanks for the info. Looks like we have/had the same problem as the cup also broke on mine. Is DSC Motorsports a good source for the stock rockers? Anybody wanna buy some Harland Sharp's cheap?

 

If you would like to run the harland sharps you can cut a recsess on the rocker where the cup sits. But any place like jegs and summit can get you the stock adjustable rockers.

 

I would make sure that your push rods are not rubbing/hitting on the intake. That will cause them to bend/break! Also make sure you have some clearance between the cup of the pushrod and the rocker. If not you can shave a little on the cu If that doesn't do it then you can clearance the rocker.

 

let me know if you wanna ditch the harland sharp's..

 

e-mail me kjreppy@msn.com