engine and drivetrain Cylinder Head - Worth The Rebuild?

[bahllr]

I was planning to rebuild an e12 cylinder head I got from a buddy and took it to the machine shop to get checked out.  It appears to be in good condition except for the fact that the height is out of spec.  It measured at 5 inches 48/1000s.  Spec, if I remember correctly, goes as low as 5 inches 62/1000s.  So this is 14/1000 to short.  Machine shop said 'they can work with it'...but I wanted to know:

 

Is that a problem?  Should I push forward with the build or is this a problem with interference with pistons or some other concern?  I thought it would just, marginally, increase compression ratio - but I wanted to get some expert opinions prior to putting any money in it.

Thanks,

Ben

[Simeon]

I think it becomes more of a factor about how you deal with the cam timing as the reduction in deck height increases (assuming clearance and deck thickness OK). Not insurmountable

Edited August 1, 2013 by Simeon

[bahllr]

Thanks, Simeon.

 

I forgot to mention that I was planning on sticking with a stock cam at this point - but might be interested in a 292 at some point in the future.

[Mike Self]

You might be able to overcome that relatively small difference with a thicker head gasket.  They used to be available "back in the day", not sure if that's still true, but someone on the Board should know.  On the other hand, E12 heads are not that hard to find, so long as you're getting a good one and not a pig in a poke. 

 

cheers

mike

[Guest_anonymous]

just for reference

[TobyB]

Shoot, I do them in millymeters, but that sounds like it's .3mm short- and that's just fine.

 

If the cam journals are good and the cam turns freely in them, and the surface isn't going to need another cut

AND it pressure tests good AND there's no other damage OR cracks, I'd say you have a winner.

Those are getting hard to find...

 

We cut as much as a mm off them for racing back when heads were plentiful and high compression

pistons were 'expensive' compared to tii pistons.  That worked.  Cam timing suffers a bit, but .3mm isn't going to be a problem.

 

If you plan on a higher lift cam, do it now, since it will be a good match to the compression, and you can do a valve clearance check

and be done with it.

 

Do make sure to get the front cover cut to match the head, or you'll have oil leaks 'till the end of your days...

 

hth

 

t

[Buckeye]

Your deck hieght is already 0.355mm below minimum specs. Is machine shop going to resurface it? How much? They should.

Assume 0.005" (0.127mm), then the head will be below minimum by 0.482mm.

You can buy oversize head gasket which is 1.8mm thick ( std. Is 1.5mm), then you are still 0.182 mm short.

I think spacer are available. Talk to your machine shop

[tim385]

+1 with Toby , can run a bit under, if ya worried cosmetic do a big assortment of Mls gaskets in different thicknesses.

[TobyB]

oh, and the +.3mm gasket's still available, last I looked, if you want.  But I woudn't bother.

 

One thing I forgot- cc the chambers.  If it was cut at a taper, it's worth having the valve work done 

to even out the head.  Cheap, fast, and worth the effort to get all 4 at the same compression ratio.

 

hth

 

t

[rho]

I believe the turbo head gasket is thicker... maybe you can try that approach.