I'm curious to know how many times a set of heads can be resurfaced before it starts bumping compression up enough to warrant higher octane fuel?  

 

I would think that the machinest would take off the minimum amount to make it flat, but it's still taking off material.  

 

I know that the heads on my newly transplanted 2.5 have been machined twice in the recent past, and unknown if it had been done in the previous 190,000 miles(I would guess at least once, but just guessing).

The engine sounds good, seems to pull solid, and revs smooth...as far as I rev.  I've gotten up to 5 grand a couple of times, but I usually don't like to use that many revs, when there's another gear...I'd rather shift.  I just got it running, I don't wanna blow it up right away.

I only have a spec here for a Phase I 2.2

 

.3mm or .012 in.

 

Each time they are cut is likely to be .05mm or .002in 

 

so that's 6 cuts if they were all very thin shaves......maybe only 3 or 4 if they were deeper cuts.

 

The way to know for sure is to measure the height of the head, which is standard height of 98.3mm  with a minimum of 98.0

If the measurement is below specifications do you make it up with the head gasket thickness, or do you get new heads?

If the measurement is below specifications do you make it up with the head gasket thickness, or do you get new heads?

 

I'd get new heads.  But I suppose a thicker HG could be used.

Can the height be measured with the heads installed?

What happens if they are too short?

 

And what kind of revs are these engines happy with?  With the red area starting at 6, and the tach reading up to 8 grand, it makes me wonder what these engines are supposed to be able to do....without grenading.

 

It always feels like there should be another gear, on the highway.  And on the freeway it feels like I'm flogging it to go 70.  I'm that slow guy in the right lane....getting passed by semi trucks.  I've always had bigger vehicles, with V8 engines that are barely awake to go down the highway.  I still can't get used to how my Goldwings like to rev, either.  The '77 loves the RPMs, the '82 favors the bottom end of the tach, but will still use the whole thing, without complaining.  I foul plugs on the 77, because I tend to under-rev.