head height

[philippeF]

Hello
I discovered a problem while performing the head height measurement...
one of the six heads is 0.10mm lower than the other, i believe it's too much to keep the cam housing in the right position
(i've tried to "show" what i mean on the pic below...)

shall i work on the five others to achieve the same height ?
is it in the factory range ...?

thanks
Philippe

[racing97]

Philippe
Yes you should make the cut for .10mm. Just to make sure you need to do this, use a granite plate and a 123 tooling block as well as a fixture mounted dial indicator that you can move over the head surface to re check your measurments. You will porbably need to make a Lathe fixture for the cut. I can't remeber if that is a 917 or 908 head, and it does look new, but if the heads came from various places and if the valves are older style Tiatainium, make sure they are from current production. the older style will strech during use and hang the valve heads off the seats resulting in
no compression no start.

Best regards

[Rex Walter]

If PhilippeF checks all his measurements, and still finds that only one of his heads is 0.10 mm low, can't he add an additional 0.10mm copper cylinder base gasket to just that one cylinder? I'm just curious what the pros and cons of this are - assuming that he will end up with everything level before the cam towers go on.

Rex

[2.7RACER]

0.10 mm copper gaskets aren't available. We are talking an error of .004" (four thousands/inch). The real question here is where to cut the four thousands from the heads. That is from the top or the bottom.
I would carefully cc each head to determine how the other five heads compare to the "short" head.
I would then shave four thousands from the two heads that would end up closest to the "short" head. These heads would then be used on the same side, 1-2-3 or 4-5-6.
If all the head volumes are equal, less than 0.10cc. difference, I would consider shaving the top of two of the heads four thousands.
If there is a significant difference in the cylinder head volumes such that shaving any two heads does not get them close to the "short" head then I would consider replacing the "short" head.
Ultimately you want head volumes (ie: compression) to be as close to each other as possible.
You wouldn't want three heads with a 83cc. volume and the other three at a 85cc. volume.

[philippeF]

ahahah!......
The pic is something i found on the web, mine is only a 2.7RS head ...

I've used a granite plate, and the proper tool with a dial indicator, i'm pretty sure there's 0.10mm less on this one.
the 6 cylinders are fortunately in a 0.02mm range (height)

by the way, it will affect the RV on this cylinder if i had another cylinder base gasket, won't it ?

regards
Philippe

[BURN-BROS]

Phillippe, is that a 908 head? Whatcha doin there?

[philippeF]

burn-bros> you read too fast, i type too slow

[BURN-BROS]

ah!