I have a set of 186 heads I just dropped off at the machine shop to be machined as an original set of DZ heads were, with the big valves and all...my question is this, what type of valve guides are everyone using in these heads? The K-liners, or the larger type? The machinest told me the K-liners were only good for 10 thousand miles so he doesn't use them...any advice on this?

Personally, I would not use K-Liners either. I have used Hi-Nickel casing with impregnated Silicon Bronzed guides when installing valves with smaller stem diameters. If you're using the Stock Valve stem diameter, I believe the stock OEM replacement guides are as reliable as anything else on the market.

I also want to preserve the value of the heads too, since they are dated coded originals to my car...any ideas on what does or doesn't hurt the value? I think the machinist said he just used a solid bronze valve guide...will this devalue the heads? If so, what should be done instead?

I also want to preserve the value of the heads too, since they are dated coded originals to my car...any ideas on what does or doesn't hurt the value? I think the machinist said he just used a solid bronze valve guide...will this devalue the heads? If so, what should be done instead?

Installing hardened seats decreases the value IMHO.

Doug

I agree, and I am not having that done...but I was wondering if there is a particular method with the valve guides that is more acceptable to the restoration community.

Installing hardened seats decreases the value IMHO.

Doug
Doug,
Do you have another method of protecting the iron seats with unleaded fuel?
I never had that problem with aluminum heads. The seats are already hard.

Fred,
MacNeish really hit that topic on CRG hard. He's trying to fix an original head where a hardened seat fell out and really screwed things up. John Z and others there said there is no reason to need hardened seats with unleaded unless you are going to pull a heavy trailer at over 100 mph. I was lead to believe you needed hardened seats too, and I was going to have them put in some heads I was going to buy until I read that. I know some people are going to have different opinions about this, but if Jerry and John say you don't need them, I'm going with them.

Thanks Harv. I never had a choice with aluminum and I sure know the feeling of having a seat fall out.

maybe our unleaded is different to that in the States...but hardened seats are a must...resession on older classics/vintage has been an issue showing signs as early as 50,000 miles on a street car...
I replaced with harded on the 1st head rebuild in '86..and glad I did...All I need this time was a seat grind.

Valve guides...I have rebuilt my heads 2x now over the last 27 yrs. Valve giudes tend to show the 'puff' around the 70,000 miles and are reputed that this is a know 'weak piont' I replaced with bronze in '86 and it wasnt till around another 120,000 miles that I started to get the stratup puff again, thu very small. Im have used bronze again.

Im a bit confused here....
I would not consider better valve seats/guides as a issue with "that is more acceptable to the restoration community."
Surely simple 'improvements' like this would be acceptable...just as better rings, or for that matter, boring and oversized pistions,
the latter actually makes significate changes to the orginal engine config, and that I would consider acceptable.

I want the heads to have improvements, but not to the point where they are devalued...as in putting in the heardened seats. I was just wondering if there was a more accepted way of replacing the valve guides...that's all I am asking.