Question on Head Gasket job.....

[micah202]

I'm replacing head gasket, had the head cleaned, tested, and planed,,, with valves in place.

The tech said the valves held vacuum overnight, sounds good. Engine has 116k miles on it.

QUESTION.... since the head was planed, and the pushrods remain same length,, is there something I should be adjusting to accomodate for the (very small) relative difference of depth?

The manual doesn't seem to mention anything. It goes straight from installing pushrods, then rocker, then valve cover.
I once, ~25 years ago, had a valve break on the first hill climb after a head job. There had been multiple planing jobs done, which mightah been the cause.

Thanks for any suggestions.

[Headhunter38]

My thinking is no since the lifters are hydraulic. Any slight variations should be able to be accommodated with the lifters. That's just my thinking though, someone more knowledgeable should definitely weigh in.

[micah202]

Ah great. A friend thought they are hydraulic and that'd not need adjustment, and I've confirmed that they are,, thanks.



I still wonder how I messed up that one 25 years back. Mysteries of the universe.

[kcg795]

If the head is shaved to an extent, then yes, you'll need shorter push rods. This happened when my engine was rebuilt. The valves would not close and shorter push rods had to be made. If you end up needing shorter push rods, you'll need to run Premium because your compression will be much higher.

[micah202]

By 'to an extent',, I guess you are meaning that it's shaved considerably, like a number of times?

I gathered from responses here and elsewhere that the hydraulic lifters automatically accomodate the head being planed.

But yahh, I supposed that's what caused the past project ~20 years ago to go awry. I know it was planed twice at least.

Of course mine is all back together now. I'll likely see the result in a coupla days. Here's hoppin all is good.

[timsrv]

Micah, read the 2nd paragraph on this post: https://www.toyotavantech.com/forum/...ebuild-part-13

[micah202]

Thank you Tim, very informative!

.."Even when machinists shave heads and grind valves, there is still enough self adjustment available for things to still fall into the "happy zone". There are limits though, so if you take your head to a machinist, make sure he knows the engine has non-adjustable valves. Armed with this information he will know to make minor changes to the valve stems to compensate for other machine surface changes that occur while reworking the head.""

All assembled now, as mentioned above. Not as fine detail of work as your project, but 'here's hoppin, as I said.

The quote above is much as I had gathered from my inquiry,, though I wish I had known the Machinist can check and adjust the valve stems. ... wish I had known to ask this, a bit more hoppin than I would have liked. Here goes, probably going for start-up tomorrow.

Cheers!