I am building a 427 C5R block with LSA heads. I am using Comp Cams (T&D) 1521 roller rockers. For the rocker arms to miss the lip of the head where the push rods go, next to the intake, we had to relieve .050 - .060 off the lip of the head where it goes up to meet the valve cover. As you know the rockers set real low in the head. I though I was home free at this point until I went to put the Chevrolet Performance, part # 338875 valve covers on. On the inside of the valve cover their is about a 1/4" lip that sticks up inside. It has about a .090 wall thickness out to where the o-ring seal sets. The problem is when the valve is closed, the adjusting stud and lock nut lean even further towards the intake. This makes the lock nut hit the lip of the valve cover. Next we relieved most of the .090 wall thickness right where the adjusting stud is. This helped some, but with the valve covers bolted on, the nuts still scrape when valve is almost shut, or just opening. After they open a small amount, they move away from the intake, and are fine. T&D and Comp have been useless in helping with a solution. T&D say they NEVER had a set of LSA heads in their shop, but they know people have used these rockers with those heads. They just don' know what the people did that used them. I tried cutting one of the lock nuts on a 45 degree angle, but didn't help. I only need about .040-.050 more to make them miss, and have some clearance. If I could get rid of the lock nuts, there would be no problem. Has anyone else had anything similar ? Thank You for your time. Denny

 

Sorry> I guess I put this in the wrong forum

 

Since you have clearanced the heads and now have the interference with the cover, you likely need some different covers. All of the above will need some clearancing BTW. See here where Steve just went through this but with LS3 heads. LSA, LS3, L92, LS9 heads should be dimensionally the same for the purposes of mounting rockers and valve covers...so IMO not the heads but the covers, and you'd have the same problem with those covers and the other GM heads mentioned. The LSA, like the LS9, are thicker in some places but the covers should mount the same relative to the rockers.

https://ls1tech.com/forums/cadillac-...-ls3-done.html

He went through a few sets and landed on Pro Form.

 

Thanks for the reply. I looked at the pictures of the link you sent me. Those T&D rockers are farther away from the web of the head, on the pushrod side, it looks like. The reason I say this is it doesn't look like he had the grind the heads to give the rockers some clearance. Check out picture compared to his. Also I am using ProForm valve covers

 

I talked with Steve and confirmed that he had to grind some for HS rockers and then when he went to T&D he had to grind more. I had some LS3s that Cam Motion set up for T&Ds and they were clearanced significantly as well.

So suck it up and break out your grinder.

 

If I grind anymore I will hit the oring on the valve cover

 

I thought you were done grinding the covers and were asking about grinding on the head. What am I missing?

 

both were already ground. The head was ground to miss the alum part of rocker and the valve cover was ground to miss the adjusting stud and 12 pt nut.

 

I have the T&D rockers on Dart LS3 heads and the Pro Comp valve covers. I had to clearance my valve covers quite a bit. I did it by hand with a die grinder and it took a few hours, but I was able to make them work.

 

I am ground into within .010 of the o-ring on the valve cover, and they still hit

 

Man, That stinks. Martin Smallwood has been putting people in the Crower stainless shaft roller rockers. He said he has had good luck with those and they are supposed to have better clearance.

 

Are there perhaps multiple models/revisions of the Pro Form covers? It occurs to me that even if you grind all the way through for a half inch or so, the valve cover gasket, which is basically an o-ring, is stiff enough that it doesn't need the support there and would still seal since it will be held in by the lip on either side of the gap(s).

 

Yes. If you don't go too far, it does.

 

Have you thought of spacers between the heads and V/C's?

 

Sorry been sick. Was operated on, on 8-15. Been down for a week. Don't want to use spacers. Would still have to grind away quite a bit. How do you feel about using Comp 1478-16? They are updated stock GM rockers with the trunion kit. I talked to Texas speed and 2 other places that race ls's, and claim each has a car with 1000-1200 hp at the wheels running them. My car is only for show, no racing will be done. No harness or roll cage, and from what I understand I might be able to race it one time, but with estimated, so far, till it goes to chassis dyno, between 700 and 1000 hp, cage and harness will be needed. The car will only be on street and estimated 200-400 miles a year. Will try to sell the Comp 1521's at a loss.

 

Here's what I had to do and I ran a mr.gasket flat gasket I can get the pn if need be

 

Mr.gasket 183g