My 644 gave up the ghost

[Eugen]

Thanks Dave! Let's see what's wrong and I might take you up on it.

[Eugen]

Well, there are tell-tale signs that there was blow by between the head and body. Some fresh oil on two parts of the head gasket.

[Eugen]

Cleaned it up a bit and measured the head flatness. Not to spec; three areas more than 0.003 inches.

Dave, I really appreciate your offer to have it milled in your shop but you know it's hard for me to go away from home plus this could be done easily on sandpaper. Which I did.


I'm not sure if I should lap the valves since the head is off anyway. What do you guys think?

[propane1]

She’s a big valve engine. Woo hoo. Extra power.
And standard bore, that’s great. Neat to see the markings on the piston. Looking good Eugen.

Noel

[JSinMO]

Looking good, glad you found the issue. I don’t know if lapping the valves is necessary in this case, but I dont think it’s gonna hurt.
Do you guys use copper cote on your gaskets? I started using it years ago on head gaskets and haven’t had a leak yet.

[Harry]

Nice job Eugen, your workmanship is commendable.

Keep the Peace
Harry

[thebuildist]

Nice work, Eugen!

[DavidBarkey]

Check your valve clearance . if it is close to speck leave alone and just make any adjustment needed . If the clearance is very low then you have ware and yes do it . Sometimes it is better not to fix what is not broke .

[Eugen]

Thanks guys!

@DavidBarkey that was my thought, and adjusted the clearance last night after the kids went to bed. Let me tell you, the mosquitoes were vicious!!!

Valves were a little loose, 0.020 for the exhaust, and a little more than 0.010 for the intake. Adjusted to 0.018 and 0.008, since the specs say 0.017-0.019 and 0.007-0.009 and for lack of better intelligence I tend to adjust valves in the middle of the spec range.

This got me thinking though. Assuming that the valve adjustment nut doesn't get out of adjustment on its own, why would the gap get smaller, or bigger. Makes sense that wear on the valve seat or valve itself would make the gap smaller. But larger? All I can think of is carbon deposit in between the valve and the seat. Now I wish I had at least tried to clean the valve-seat contact. because the valve cover is back on and I'm really not in the mood to take it all out again. Meh!!

[DavidBarkey]

Thanks guys!

@DavidBarkey that was my thought, and adjusted the clearance last night after the kids went to bed. Let me tell you, the mosquitoes were vicious!!!

Valves were a little loose, 0.020 for the exhaust, and a little more than 0.010 for the intake. Adjusted to 0.018 and 0.008, since the specs say 0.017-0.019 and 0.007-0.009 and for lack of better intelligence I tend to adjust valves in the middle of the spec range.

This got me thinking though. Assuming that the valve adjustment nut doesn't get out of adjustment on its own, why would the gap get smaller, or bigger. Makes sense that wear on the valve seat or valve itself would make the gap smaller. But larger? All I can think of is carbon deposit in between the valve and the seat. Now I wish I had at least tried to clean the valve-seat contact. because the valve cover is back on and I'm really not in the mood to take it all out again. Meh!!

Valve lash getting smaller on a flat hear is the ware of the valve and or seat .
Valve lash getting bigger is ware from the cam and or lifter.
Or was not set properly the last time is possible if you don't know who did it last . Since it is not much out . It could be a combination of . Some go on the low side for better performance . Some go on the high side so it is longer before it needs resetting . I perfer the middle as well, I am not racing it .