turbo_Z

In about 2 weeks I am finaly going to have time to install my LE heads but Lloyd said I needed some GMPP guideplates. Currently and for about 10k+ miles I have been running the Comp gps w/o any trouble. Now i did notice the rockers arent centered perfect on the valves but like I said no problems and I dont exactly baby my motor. From those who have handled both the GM and Comps... is there really any significant difference between them?

94zgreenmachine

Llyod told me the same thing when I sent him my heads. The gm plates only cost $25. I suppose with higher rpm the potential for more damage would be likely but I just took his word for it. $25 spent now would save you way more $$$$$ down the road.

turbo_Z

$25 is reasonable. How centered did the rockers arms appear to be on the valve stems? I know some guys complain the geometery is still crooked even with GMPP guideplates.

94zgreenmachine

Don't know. I should be getting them back this week or the next. I mean I just sent the heads to him . He should of had them Monday so I won't know till I get it together.Llyod said something like the valves are offset just a bit and that no one but gm makes the right ones, but I'll tell ya I don't want to be the one to find out what happens otherwise

12SCNDZ

You're side loading the valve tips with the COMP plates. A "best case" scenario is that you'll only wear out valve tips, rocker tips, and valve guides more rapidly. A "worst case" scenario is you break a few pushrods, bend a few valves, or destroy a few rocker arms. It's a FACT that COMP plates won't work on an LT1 for very long. The LT1 has .050" wider valve spacing than a typical SBC. COMP doesn't even make plates for an LT1.
I lived through this when I did my head/cam swap. There were quite a few tips that were substantially off when I first tried bolting on a set of COMPS. I can't believe anyone has ever used a set of them and not noticed something wasn't right when they first tried installing them. Obviously there's waaaay too many people out there that just don't check these things

Frank

sleepy_z28

I couldn't even get my Comp plates to go on my heads. The bolt holes were to close together. Did some searching on this site and realized what was wrong, even got the part number for the GM plates. The GM plates fit perfect.

shoebox

If you want to see the difference, look here. I assume the CM plates are the same design as the Comps (may even be the same plates).

turbo_Z

One of these days I will ask a question you won't have the end all answer for.

I ordered my Comp guideplates from Nu-tec a couple years ago and Nick knew what I was putting them on but he didnt say there would be any problem. My rockers are aligned just like the ones pictured for CM guideplates. It does look like the GM ones align the rockers better though. That is all I needed to see. Thanks.

Fastbird93

Shoeboxs' pic is a good example, as well as the one found HERE

You can see how the LT1's .050 wider pushrod offset was wearing the comp guideplate (on the bottom) down.

arnie

I've seen/witnessed first hand, the unusual wear on roller rocker arms removed from heads, removed from a running engine, originally assembled by Nu-tek. It is amazing, the quality of work some 'outfits' push out the door, and then actually call themselves professionals. Sad, even some (so called) pros do not know any better! As long as their customers know even less, they've got the green light to continue doing 'shoddy' work.

truedualws6

I did the same thing and initially installed the Comps and then switched
to the GMPPs. The difference is noticable. I'm glad I did it, but have heard
of many that are running the Comps with no problems. I had noticable wear
on the Comp guideplates when I pulled them, plus the roller tips of the rockers
were not dead center on the valve stem. With the GMPPs everything is right
on center.

CCCCCYA

There really is no GMPP vs Comp argument. The Comp's simply don't fit. Yes, they are close, but close isn't quite good enough on an engine. Get the GMPP plates. It's the correct part for LT1 cars.

Dave C.