7.4/454 Cam Upgrade Selection

[Motrhedx81]

Realized something when trying to assemble the new valvetrain components. I had read it a while back but forgot until I was messing with it. Figure I'll list it here for other folks' future refernence. The rotator eliminators will have to be modified to accommodate a couple of things...

Inner diameter: the eliminator are labeled as "exhaust rotator eliminators". The ID fits the valve guide bosses on the exhaust side just right. For whatever reason GM decided the valve guide bosses on the intake need to be about .010 inch larger diameter. This requires that the eliminator installed on the intakes have the IDs opened up .010-.015 inch.

Spring height: the comp valve springs I have list an install height of 1.900 inch. Some of the eliminators will have to be modified to get the springs to that 1.900+. On my particular heads the measurements are showing I'll need to take up to .010-.015 off the thickness of some of the eliminators.

All in all, not too bad, just another step/thing to work with.

 

[Supercharged111]

Which eliminators did you get? Mine came in a black and yellow box and fit both intake and exhaust.

 

[Motrhedx81]

The 4779. I didn't see any others listed on Comp's website.

 

[Schurkey]

Comp offers three part numbers of rotator eliminators, in sets of eight (-8 added to part number) or individually. The description of these on the Comp web site is entirely inadequate.
4779
4698
86603

On my L29 heads--which I bought used off of a seller on eBay--the exhaust valve guides were separate, pressed-in items while the intake valve guides were machined from the head casting. The radius at the bottom of the intake guides interfered with the underside of the rotator eliminator shims. The exhaust guides had no radius since they're a separate piece pressed-into a hole in the head. So only the radius at the bottom of the intake guides needed modification--and not all of them. Only two intake guide radiuses on each head needed trimming.

 

[Motrhedx81]

I think the difference here is that my heads are stock in terms of the valve guides (at least for 2000 model year heads). Sounds like yours have been modified. I've seen other posts and videos that talk about needing to open up the ID on the intake eliminators. I had to use the 4779 eliminators because the 4698 don't fit the Comp 911 springs I'm using.

 

[Motrhedx81]

Has anybody ever seen a cam card for the 454HO cam (p/n 24502611)? I've searched quite a bit to see if I can find the intake centerline, but nothing. One didn't come with the cam from Summit either. I degreed the cam and came up with 106°, which seems like it should be right.