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> Question for you T4 engine builders, Deck height way off---Too much deck ht!
Borderline
post Jan 30 2007, 10:38 PM
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I've got my case together and was checking my deck ht. My readings average from .074" to .080" for all four cylinders without any shims. The problem is I am shooting for .040" to get my compression ratio up to 9.5:1. This is my first T4 build. I have built several Vee motors in the past and never had this problem. Is it possible to shorten the cylinders? I just did a quick measure of the height of one cylinder. It is 3.62" from the case sealing surface to the top. Does this sound about right? Everything was going to well. Something had to go wrong (IMG:style_emoticons/default/mad.gif)
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Brando
post Feb 1 2007, 10:49 AM
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QUOTE(Twystd1 @ Jan 31 2007, 11:17 PM) *

Or...

Off set bush the small end of the rods......... Hee... Hee..

Then re-balance the whole assembly......

Naw...... Just cut the cylinders Brando.

OR:

Sell em on samba. Cut your 1.8s and buy KBs.!!!!!!!

C


Already got the KB pistons... Just need the cylinders machined down. I'm trying to sell my old 94's with their pistons since they only got like 3k miles on them...

Ah well. It's only money, right?
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Borderline
post Feb 1 2007, 07:50 PM
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My original intent was to buy the KB pistons with the AA cylinders, but when I finally got around to order them, they weren't available. I was told something to the effect that they weren't worth the extra expense. Now I believe they available again????

I have found a local machine shop (Ray's Precision in Santa Clara) to cut the cylinders down. Now all I have to do is figure out how much. I was shooting for .040" deck ht, but several people have questioned that as being "borderline" LOL
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nebreitling
post Feb 1 2007, 08:01 PM
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bill, you may in fact be "borderline" lol, but 040 is an absolutely fine deck. i wouldn't go much lower, but you should be fine at 040. what are you heads cc'd at?

9.5:1 ought to work fine on 91-octane.
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Brando
post Feb 1 2007, 09:24 PM
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I think the lowest you can go is .030" if you want to roll the dice on a 'moneyshift'. It all depends on your valvetrain geometry. Radical lift and duration increase the chances of slamming valves into cylinders with low deck heights.
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Jake Raby
post Feb 1 2007, 09:30 PM
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QUOTE(r_towle @ Feb 1 2007, 08:37 AM) *

I have a question.
Is there a reason that these set are manufactured like they are?
I assume that a run was made, and that needs to be sold off.
Can input be provided to the manufacturer/distributor to change the specs for future runs of these parts?

Seems like it should happen if tha parts are just wrong...or are they correct for a BUS motor and wrong for a 914???

Rich


They have been like this for years the spec of those cylinders really hasn't changed since 1998!

The newer AA cylinders aremuch better, we finally convinced to change their castings late in 2006 and because the cylinders are so much better we can actually offer a massaged 96mm cylinder specifically adapted to the KB pistons and hastings rings.

Several times I have contemplated dropping the entire AA line due to fluctuating component quality. we have to QC all those components with high scrutiny, but when we have bad parts they swap them out without issue..
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r_towle
post Feb 1 2007, 09:34 PM
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QUOTE(Jake Raby @ Feb 1 2007, 10:30 PM) *

QUOTE(r_towle @ Feb 1 2007, 08:37 AM) *

I have a question.
Is there a reason that these set are manufactured like they are?
I assume that a run was made, and that needs to be sold off.
Can input be provided to the manufacturer/distributor to change the specs for future runs of these parts?

Seems like it should happen if tha parts are just wrong...or are they correct for a BUS motor and wrong for a 914???

Rich


They have been like this for years the spec of those cylinders really hasn't changed since 1998!

The newer AA cylinders aremuch better, we finally convinced to change their castings late in 2006 and because the cylinders are so much better we can actually offer a massaged 96mm cylinder specifically adapted to the KB pistons and hastings rings.

Several times I have contemplated dropping the entire AA line due to fluctuating component quality. we have to QC all those components with high scrutiny, but when we have bad parts they swap them out without issue..


Im keeping all my 94mm cylinders from now on....just put them on the shelf for future motors...get them opened up to 96mm when needed.

Rich
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914werke
post Feb 3 2007, 03:21 PM
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QUOTE(Brando @ Jan 31 2007, 11:00 PM) *

Actually 0.05" difference in height than stock without gasket or shims. The piston is 0.03" shorter, the cylinder is 0.02" longer. Add the two...

So you either need different pistons and machined cylinders, or lose the CR.


Whoops. So Ok back to .03 short of OE pin to top if using the opened Mahles
and AA Pistons. Assuming stock CC volume what whod the CR be...
I need one of dem calculators (IMG:style_emoticons/default/headbang.gif)
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messix
post Feb 3 2007, 06:05 PM
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lots of calc here http://www.ajdesigner.com/phpengine/engine...ssion_ratio.php
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