How many of you out there have gone through the expense of changing valve seats on older heads? I know your supposed to and all but I have run several motors with the older leaded style valve seats with no problems, although I also didnt try to get 75,000-100,000 miles out of the motor either.

Canada has a valve suppression additive in their Shell gas pumps. Not sure about the US Shell stations. It has been tested to lub the seats better than the old leaded gas! Or you can go to your local GM dealer and buy a can of valve resession additive.

Mark

[This message has been edited by COPO (edited 09-05-99).]

I think youve hit the nail right on the head,
youre not trying to get 100,000 miles out of them, I have played plenty with this issue. may be its me but it seems that my engs. with solid cams, didnt waste the seats as much as the ones with hydraulics. I think the hydraulics may hold the valve open some of the time & actually allow the seat to be erroded quicker! so if you want em to last probably oughtta put hard seats in em, if youre gonna tear it down again soon, why spend the money?

It seems that if a valve job is done on a head w/o the hard exhaust seats this increases the chances of having a problem, if the heads are left alone the leftover lead from the olden days is usually enough.

Tom

I had a 69 chevelle with 3:55 gears, 14" tires and a lot of 3000 rpm cruising with a small block, and after a few years and about 20k miles pulled the engine after selling the car..when I pulled the heads the seats were so bad that the valves were sunken into the head off center and just had enough material to get new seats put in. These heads looked great when I first put them on the engine, didnt take long to ruin them. If
you plan on driving regularly I would get the hardened exhaust seats.

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70 chevelle ss396 conv
66 chevelle ss396 hdp/conv

Seems like the heads I've seen with bad seats also had worn guides. Hard to tell which caused which, but probably the unleaded gas had something to do with it. Still seem to run quite a while before trouble sets in.tom