Head decking: How much do I remove to get 11:1 c/r

[amalventano1@comcast.net (Allyn)]

> Thanks for the info Allyn!  This brings up a question: what is the head
> measurement (valve cover mating surface to deck) on a new JH head?  If
> mine's been shaved before, that would have to be taken into account,
> correct?

yep

> Repositioning the tensioner sounds like a PITA.  How about adding a
> steel "band" around the belt surface of the tensioner pulley (welded or
> otherwise securely fastened)?  Increasing the circumferance of the
> pulley would give the same effect as moving it right?  Any other ideas?

true, but it would have to be on there VERY securely. the possibility of
killing your engine should anything go wrong with it.

> Thanks!

no prob
Al


> Mark.
> 81 S ABA/JH/4K frankenproject
>
> --- Allyn <amalventano1@comcast.net> wrote:
> > with that block/head and 10:1 comp your chamber space is 55.12 cc's.
> > for 11:1 you need 49.61 cc's, so you need a diff of 5.51 cc's
> > aba block bore area (82.5mm) equates to 53.45 cm^2
> > 5.51 cc/53.45 cm^2 = 0.1031 cm = 1.031 mm = 0.0406 inches shaved
> >
> > if the numbers you gave us were inches, that .04 is going to exceed
> > the
> > minimum spec (~5.20)
> >
> > - i believe that the minimum spec is for the timing belt tensioner to
> > work
> > properly. you have to change the tensioner location if you go below
> > the
> > 5.219 number (belt will be too slack, even at the tensioners 'max'
> > position).
> >
> > Al
> >
> > Allyn Malventano, ETC(SS), USN
> > 87 Rieger GTO Scirocco 16v (daily driver, 170k, rocco #6)
> > 86 Kamei Twin 16V Turbo Scirocco GTX ('it has begun', rocco #7)
> > 87 Jetta 8v Wolfsburg 2dr (daily driver, 260k, 0 rattles, original
> > clutch,
> > driveshafts, wheels :)
> >
> > ----- Original Message -----
> > From: "Mardak" <maardak@yahoo.ca>
> > To: <scirocco-l@scirocco.org>
> > Sent: Sunday, May 26, 2002 3:55 PM
> > Subject: Head decking: How much do I remove to get 11:1 c/r
> >
> >
> > > I've got a JH head going on an 2.0 ABA block.  The head measures
> > 5.240
> > > from deck to valve cover mating surface.  Bentley minimum
> > measurement
> > > is 5.219, so I'm fine there...  From what I've read, the ABA/JH
> > > combination yields a 10:1 comp. ratio.  So, based on these numbers,
> > > does anyone have a recommendation on how much to remove without
> > cc'ing
> > > the head?
> > >
> > > Thanks,
> > >
> > > Mark.
> > >
> > >
> > >
> > >
> >
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