exhaust guides for Gn1s

[mygn276]

I am having my champion heads cleaned up after very little miles ran on the car. So i thought everything would check out fine by the machine shop. But was surprised when i was told my exhaust valve guides need relined again after two years. The valves are very sloppy. Has anyone found out whats the best exhaust guide to use on the gn1 heads? I cannot keep replacing these every year. Thanks

 

[750H.P.V6]

I'll give you a little history on why Champion uses steel guides with K line liners. Back in the begining around 1999 the first heads had bronze guides and they must have been a bad batch. The guides couldn't handle the elevates EGT's you see in a turbo application. They fell apart, the pieces went thru the turbo and made a mess.

Steel guides with K line inserts aren't really designed for extended usage like you would see in a street engine. They are designed to be serviced and replaced at regular intervals.

What we did in the past when we still ran Champion heads is to install a good quality silicon bronze type guide something like the ones CV sells. I know at one time Billy Anderson was cutting the tapered end off the guides to maximize the wall thickness also. I never tried this myself and didn't have a problem.

I hope this helps.

Neal

 

[mygn276]

Thanks Neal. But what looks to be the problem we are having with aluminum heads is that there is too much heat around the guide area. A thin guide that has a lot of heat soak. This is why I believe the iron heads are better for the street. There is alot of material around the guide to dissipate the heat better, plus the fact they are made of iron.

 

[Nick Micale]

Like Neal stated, the K-liners do NOT like higher temps as we have found this true on many Champion alum heads. We also replace them with bronze guides we machine to fit. We do not see problems on street alum heads once this is done.

As far as iron heads, in the hundreds we have done, most all of the guides are worn enough to need guides installed, and we prefer bronze.

Certainly an alum head will dissipate heat quicker than an iron head, with or without bronze guides.