I had to remove my vc on my truck yesterday to find out why the exhaust valve was letting 50% of the pressure out during a leakdown test..appearently its been this way for 60k miles...but anyway I noticed the GM guide plates have some severe wear on them... I just put these same parts in my 95 TA.

Is there another brand of guide plates that fits well and are hardened throughout instead of just surface hardened like the GM ones? Or should I just not expect them to last more than 50k miles. The chromemoly prs were fine.

 

Look at the TFS guideplates or Isky adjustables.

 

Whatever brand Lingenfelter uses, unless it's their own, work well and line the rockers up onto the valves perfectly.

http://www.lingenfelter.com/Merchant...Category_Code=

 

Knowing that some people have said some of the GM plates are not hardened properly, I still have to wonder why some are getting such severe wear. IMO, the plates should not be doing that much work. I have a feeling that those with sever wear problems might have valve train geometry issues that are the root of the cause.

 

your right......its seems to be more of a geometry issue to get so much side pressure on a PR. Something in the valve train is off

 

I don't think that is the case here. The wear spot on the lash cap top is perfectly in the middle. In fact I measured the PRs in this motor and they are the exact length of the ones I measured to use in my '95 TA, and this motor has the exact same cam and valve train besides springs.

These guide plates have a little over 60k miles that I'm sure of since its been in thruck... the motor itself has 120k mile son it, not sure if the guide plates were changed when it was installed in the truck or not, these could be the original LT4 guide plates. I had a shop tear down the top of the motor and heads before installing in the truck.
There are not currently any issues with the motor, I only noticed the wear when the vc was off.

Thanks for the tips on the LPE and TFS plates. Just by looking at that pic of the LPE plates, those look just like the GM plates, but without being able to see the numbers stamped on them I guess they could be different or maybe they are completely hardened by LPE.

 

I know the TFS 30400623-8 guide plates are hardened real well and have that black look to them. MUCH hader than the GM guide plates.

I had never seen the Lingenfelter ones before but they ahve the same grey color as the GM guide plates for what it is worth.

As long as the geometry is correct, the guide plate should not wear. When dealing with LT1 heads, the guides are installed blank with no hole and the holes are drilled later on and NOT centered in the center of the guide. The variance here might be enough for the GM guide plates to allow everything to line up correctly on some set ups and not on others.

Getting the geometry right is more than measuring the PR length. They can also have the rocker tip not be centered on the valve tip.

The people that just slap the stuff together and do not check this stuff are the people that have the problems.

If the rockers are centered side to side on the valve tip and the correct PR length is used, the guide plates will NOT wear and the guides will live MUCH longer.

Lloyd

 

Thanks for the info Lloyd, the tips appear to be on the center of the valve, but now there's so much play in some of them its hard to tell. I didn't assemble this so I can't say what it looked like before the wear.
I'll be bringing these heads to you in a few months as it looks like there's an issue with the #1 exhaust valve not sealing up, get the LE2 treatment.