[Jay S]

If the knurling was done on a guide that was still with in specs, not what you would classify as loose or shot, just needs tightening up some, that is quite a bit different than knurling something that is loose and shot. Knurling the one than is still pretty tight will last longer than if you just left it and ran it. Loose and shot always needs liners. I have had some that only received knurling on a couple valves that were slightly lose, still with in specs. Those all went more than 100K miles, and out lasted the vehicle in most cases. Those were stock engines though.

You kind of have to go with your machinist’s opinion and judgement. I know of one local machinist that the heads get liners no matter what you bring in, even new heads that need nothing. Lol….There are fewer and fewer machinist shops around to do the work. If your not careful you”ll end up on some 6 month or year waiting list.

[PAUL K]

Originally Posted by Jay S

If the knurling was done on a guide that was still with in specs, not what you would classify as loose or shot, just needs tightening up some, that is quite a bit different than knurling something that is loose and shot. Knurling the one than is still pretty tight will last longer than if you just left it and ran it. Loose and shot always needs liners. I have had some that only received knurling on a couple valves that were slightly lose, still with in specs. Those all went more than 100K miles, and out lasted the vehicle in most cases. Those were stock engines though.

You kind of have to go with your machinist’s opinion and judgement. I know of one local machinist that the heads get liners no matter what you bring in, even new heads that need nothing. Lol….There are fewer and fewer machinist shops around to do the work. If your not careful you”ll end up on some 6 month or year waiting list.

Amen!

[TRADERMIKE 2012]

I am letting the Head builder take his time on these Heads, I even paid him in advance, the fact that he is cutting all 8 Intake Bosses as a matter of his own practice procedure, says he is meticulous, perhaps he knows which process to use and when?

For the record, this motor never smoked, however I had in my spare parts, within the gasket set, were the positive and Umbrella seals, thus I deduced that the former owner never addressed the Heads, so I installed them where they could do some good.

This 1967 428 ci HO Engine is stock and possibly Blue printed and balanced to spec. for the very reason that the lower end has been tampered with. Who goes into the lower Crank and pistons and race tricks the pistons if not there making the best of racing ability to stay within scca rules for example only, as I stated before, my own father sent his motors out to be Blueprinted and Balanced for racing in Gymkhana's on Long Island N.Y. @ Mitchel field, former air force base, before the Nassa Coliseum was built.

[Kenth]

1. Pontiac never cut just the exhaust valve guides from factory, IF they cut it was the intake valve guides OR both intake and exhaust.
I have had #670 heads from a 428 that none of the guides were cut and #670 heads from 400 engines were the intake valvguides were cut for positive seals.
There is absolutely NO point just cutting the exhaust valve guides only (not even a "race"-engine would benefit from this).
Are you sure you´re looking at the exhaust valve guides?

2. NO Pontiac heads ever uses "umbrella" seals from factory, like f.e. Chevy engines did. Pontiac used "positive" seals on the intake valve guides for the 1967 and later "high performance" 4-barrel engines.

3. ALL, except the RamAir, engines also uses oil shields and O-rings in the retainers.