I recently fired up my 430hp/355 cid mouse for the first time. It is a full hydraulic roller motor. We were unable to get the clattering of the roller rockers to stop. I ended up putting 75 miles on the car. I called ProPower out of Florida which built my Canfield aluminum heads. I explained to them what the problem was and he asked what pushrods I was using. I had been using stock length Ferrea valves, the heads were unshaven, the block hadn't been decked, 1.5 Scorpion roller rockers...the only thing could have been the pushrods.
Now when we started this project, my buddies and I hadn't counted on it getting this out of hand. (no surprise) No one had experience with the exotic aluminum head-roller cam set-up. When the pushrod length came into question originally, we didn't know really how to measure, so I called a "reputable" speed equipment place and told them my whole set-up. They told me that stock length pushrods would be acceptable.
Now this brings me back to ProPower which built my heads. They said that roller cams have taller lobes and would neccessitate the using of a shorter pushrod. He said that what I was using was for a stock-type flat tappet cam. They were 1/2 inch too long. I have since parked the car. I ordered new roller cam pushrods based on what I and ProPower know about my combo.
Hopefully, this will cure my problem. I have maintained excellent oil pressure, ran a constant 165 degrees and detect no noticeable "miss" in the motor. It seems to run fine, has never been spun over 2800 rpms or over 60 mph. Could I have harmed the motor? We have ran it extremely "loose" during these 75 miles. What should I expect or look for when we install these pushrods?
What is the proper technique for measuring pushrod length? I was assured that the only "X" factor I have is the Canfield heads deck height. ProPower has told me that the difference between the aftermarket heads I have and stock ones is minimal. What is stock height...and how do I measure the deck height of my aftermarket ones?
I really hope I haven't grenaded this money siphon of a motor....Thanks guys!

I doubt you've grenaded it or even hurt it. Moroso or somebody like that sells a little plastic tool that slips over the rocker stud, use it when the lifter is on the base circle of the cam, not on the lobe. It's sort of a "T" shaped thingy, the arms are supposed to hit the pushrod and the valve at the same time. I've used it, I think it's pretty accurate. Another method involves eyeballs, put the rocker arm on, adjust the lash if any and turn the engine til the valve is half-way open. At this point, the tip of the rocker should be in the middle of the valve.

This is one of the little details that is almost always neglected unless the builder is somebody who does this for a living all day every day. Anytime you hear somebody bragging about how he slapped together a SBC you can bet he skipped this. That's why his valve guides are shot after 20K miles and it's smoking and burning oil. Of course, the guy always blames the "crappy parts they're selling". Good thing you caught this, saved yourself a lot of grief.

Tom

There is but one way to find the correct push rod length, check it! The cam with big lobes does not dictate an automatic change of the push rod length.

The correct way to check when you are putting the motor together is to put on a set of checking springs, use a locked solid lifter, put the rocker on the stud and adjust it to zero lash, turn the motor over by hand and observe the nose of the rocker as it travels through its cycle. I forgot to mention to put a little white grease on the top of the valve stem so it will leave a mark you can see. The mark should be near the center of the valve stem.

This job is made a lot easier if you have adjustable push rods, you can lenghten or shorten these at will to get the rocker in the correct position.

BillK and I just finished a 406 for boat that is using Sportsman heads, the push rods are .200 shorter than stock.

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Wally
Gold #67
67 malibu

Justin,
Heres something I found on Lunati's web site: www.lunaticams.com/TechNotes/TechNotes.html (http://www.lunaticams.com/TechNotes/TechNotes.html) You will have to go down the frames menu on the left side of the page and find "roller rocker geometry"
Trick Flow also has a nice tech sheet in thier catalog, e-mail me in the morning (so I will get it at the shop) and remind me to bring it home and scan it for you. The biggest problem you are going to have now that the motor is assembled, is checking this without collapsing the hydraulic lifters. We actually have some lifters that we have modified (made solid) just for this purpose. Liek Wally said, the time to do this is when the motor is on the stand, with checking springs, but you are past that now. Hopefully the stock length pushrods will work, but it never seems that way.

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

1971 Heavy Chevy - original owner
Team Chevelle #100



[This message has been edited by BillK (edited 07-19-99).]