Engine: Remedies For A Pathetic Valve Job

[JoeHall]

The machinist, who did the valve job on my recent 289 rebuild, was "uncomfortable" installing hardened exhaust seats, from Phil H., so I said OK, just do a regular valve job, which he did. In grinding the seats, of course the exhausts require deeper grind. A competent machinist would also grind each valve stem tip, sufficient to restore OEM specified tip height. I don't know what that spec is, but my collars measure 1.950" - 2.050", and the tips are .125" - .150" above the collars, so a guesstimate is 2075" - 2.200". The PROBLEM with excess valve stem height: the valve clearance adjustment screws have less remaining threads, and after a few valve adjustments, there are no threads left. (I learned this decades ago when I had a pair of heads surfaced .030" extra.) With rockers removed, laying a straight edge across the valve tips on each bank, the exhausts are .040" - .050" taller than the intakes. Due to rocker arm ratio, this means .060" to .075" less threads on the exhaust adjustment screws.

I can fix this several ways: use thicker, sandwich head gaskets; fabricate shims to go between the rocker shaft pedestals and head; install early 259/289 pushrods, which are about .125" shorter. I am inclined to just take the heads to another shop and have them done correctly, to include installing the hardened exhaust valve seats. But the CASO in me is saying install early, shorted push rods.

Comments? Suggestions?
Thanks in advance.

[PackardV8]

Hi, Joe,

As usual, you understand the tradeoffs.

And yes, installing hardened exhaust seats in Studebaker V8 heads is tricky. There's just not enough iron below the two center exhaust seats; it's all too easy to cut through into the water. We use a thinnner than usual seat so as not to have to cut too deeply.

We set valve stem installed height to 2.032".

jack vines

[christophe]

I ran into the very same problem while rebuilding my Simca 1000 engine which had a cylinder head coming from an automatic car (10,2 to 1 CR). I used 2mm shims between the rocker shaft supports and the head.

[Jeffry Cassel]

Well, you don't really need hardened seats 'cause we don't drive a lot of miles and we don't usually drive hard. I've had seats installed and he didn't seem too stressed by it. I'd look for a new machinist and new heads. I--after several bad experiences with 'shops' --did my own valve jobs. It isn't that hard. The man who lives just down the road did my last one--but he is retired now, too. I might try shims as it is cheapest option. The shorter push rods might worry me a bit.

[mbstude]

Well, you don't really need hardened seats 'cause we don't drive a lot of miles and we don't usually drive hard.

I guess you haven't followed Joe's postings on this forum too closely. He's been using his Hawks for daily transportation and long haul road trips for the last 40+ years.

[Jeffry Cassel]

Most of us don't need them. Factor in the risk of un-seating the valve seat. My favorite machinist used that convincing argument to talk me out of them. Anyone tried a quart of Diesel per tankful as an upper cylinder lubricant?

[yeroldad]

I use Lucas. It's made for gas motors. Saved valve seats on several motors over the years, and many miles. Around a quarter to a half cup most every time I get gas. And it keeps the rest of the motor(s) clean and provides some 'cushion' for the seats.

[Hawklover]

In my R-1 Avanti I add MMO and Lubrizol to 93 pump gas, and try not to drive in the extreme heat of the summer.

[bezhawk]

My machine shop will not install the Stude suppliers valve seats as they are too thick and will take a chance on cutting into the water jackets. He uses someting much thuinner, and I've never had problems.

[JoeHall]

My machine shop will not install the Stude suppliers valve seats as they are too thick and will take a chance on cutting into the water jackets. He uses someting much thuinner, and I've never had problems.

I have Phil H's seats, which is says work well. Not sure where I got them before, but have had several pairs of heads converted over the decades. Never any problems. Knock wood.