Rang up the gasket maker for the AU and BA gasket. Their specs for gasket thickness are .35mm BA (it is a two shim gasket) 0.62 AU (it is a 3 shim gasket). They are both made in Japan.

Looked up the BA CD and they state that piston to deck is 0.3mm and Head gasket thickness is 0.25mm but 0.3 at the bore. Indicating piston to head of 0.6mm (or 24 thou)

The ellery AU manual (3rd party info) states AU spec for piston to deck is 0 to 0.3mm.

So from this info it seems that these engines are running much tighter piston to deck clearances without a problem.

Seems I may not have to touch my pistons.

Does that use a normal or metal head gasket.


I would really like people to measure up the piston to deck of their AU and BA engines just for interest sakes. Even the e-series

One of the clearance figures I gave is wrong. The BA piston to head clearance is actually 0.5mm from the CD (acidently read the wrong figure)
So this makes total clearance of 0.5 + 0.3 = 0.8 (32thou) being used in the BA.

Still looking for piston to head clearance measured from a stock engine if anyone can acurately measure.

Thats just the piston down the bore clearance..ie how far down the bore the piston sits @ TDC

Hi

Clear come confussion here. people are talking about two differant clearances.

I had 27thou piston at TDC to the top of the block clearance this is not piston to valve clearance , this plus the head gasket thickness compressed and the thickness of the head and how far the valves are sunk into the cylinder head is the clearnace we are talking about here.

I had 27thou piston at TDC to the top of the block clearance , I made this to zero clearance and machined a little more of the block/pistons again and the pistons are now flush with the block surface.

The piston to valve clearance is a issue.

I machine a further more material from the cylinder head that I'm using on top of a AU bottom end.

I haven't yet measure the compression ratio to have a precise measurement.

The required piston to valve clearance is 180 to 200thou

The methods to measure vary. One can use plasticine method where you put some plasticine on top of the piston and place the head gasket and head back on the motor with all the necessary rotating assembly and see how much the valve compressors the play dough this is the piston to valve clearance we are taking about.

In my case i had both the inlet and exhaust valves hit the piston engine couldn't be rotated at all.

Requiring both inlet and exhaust valve reliefs to be machined in the pistons

simple method is bolt the head onto the block and attach a dial indicator with a long travel needle and with some method push the valve open until you touch a piston that is positioned on TDC the amount of travel the valve moves is you piston to valve clearance.

It is most critical or evident on the opposite cylinder . Say number one piston is TDC firing then cylinder six the piston is also on TDC but on the exhaust stroke mean the exhaust/inlet valves are open/closing at the pistons highest point in travel. the to come close together as they travel passed each other.

If there is not sufficient clearances at this point in time of the pistons travel the valves will hit the piston and we know what the end result would be .

There are many vices on the market place but you need a milling machine and special cutters very expensive and there are some special tools that isky ( us a electric drill in the hand method or just normal hand turning power ) camshafts make to fix this problem of piston to valve clearance when high lift camshafts and pop+up pistons are used or when someone goes crazy and removes a lot of metal to bump up the compression ratio to yield more horse power.

Here is a example form the websit it self http://www.iskycams.com/votc.php for a better visual for understanding

http://www.compperformancegroupstores.c ... ode=PISTON

Compound Angle Vise - 4.600" Piston $779.95
http://www.compperformancegroupstores.c ... ode=PISTON

http://www.iskycams.com/techinfo.php

here is a very good example http://speedtalk.com/forum/viewtopic.php?t=8565
Just my tow bobs worth.

 

 

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Last edited by FPV_GTp on Mon Jan 07, 2008 9:42 pm, edited 6 times in total.

sorry double posted