Dear All,

At last I am installing my cam to my Slant. I was told by the gurus to measure the Static CR and work till it is 9.0:1. Today I have measured and it is as fallows:

Combustion Chamber: 56 cc
Piston Dish: 13.346 cc
Piston Deck Clearance: 0.1574" (4 mm)
Compressed Head Gasket: 0.035" (0.9 mm)
Head Gasket Bore Diameter: 3.476" (88.3mm)
Cylinder Bore: 3.425" (87mm)
Stroke: 4.124" (104.77 mm)

With this values I calculate 7.2:1 CR... where did I go wrong? I measured the combustion chamber by syringe, ok it is not precise but that much?

There should be something wrong, heeeelp!!!!

Based on the info you provided, I come up with: 7.32

_________________
11.02 @ 120.56
http://www.youtube.com/watch?v=EAxRmoDgsdY
Chassis dyno
http://www.youtube.com/watch?v=wd6hFGzLJMc

exactly... and I have shaved 0.047" from my head before cam installation. (which I thought it would be safe without cam)
The doc told me RV15M needs 9:1 CR. Even if I use a flat head piston and shave 0.1" (47 cc chamber) more it will be just 7.86:1. I guess I am missing something...

shaving 0.1" from the head should delete 14.87 cc from the chamber. If we accept its 58 cc than there should be 43 left. and it just makes 8.18:1. My piston dish volume is 13.346 cc, is it possible that I miscalculated it?

This number is suspect.
Are you saying that the pistion is -.1574 "down" in the cylinder?
When using a "metric" type piston (2.2 family) and a 7 inch c to c con rod, piston deck height should end-up near zero.
DD

yes, it is -0.16 below deck... And I am sorry I pm the same question to you I am a little frustrated... Do I have wrong pistons? Maybe I may compare new pistons with mine... D

So... what pistons do you have and what connecting rod?
DD

well, I do not know.. they do have 13.346 cc dish on them... how can I identify a slant 6 piston?

Let's back-up another step and get some history on what you are working with.

Is this an old engine that you are changing a cam on or is this a "rebuilt" engine where parts have been replaced?

If this is a older "factory" engine, give us year & modle of the vehicle.
Is this an "export" vehicle / engine? (lower compression)
What fuel is avalable in your area?
DD

Ok, I have a Dodge power wagon truck but previous owner swapped the original V8 engine with a slant6. I live in Turkey and in Turkey we have a chrysler factory which produced many 2wd pickups with slant six. My engine serial number is 76C2252328 (if it means anything) so I do not know which year it is (is it 1976? ) This is an old engine that I am changing a cam and changed the head (port and polished by me and shaved 0.045") changed the valves and springs. I will replace springs again with the cam. My engine is disassembled today and I measured the chambers... this is the story so far...

<a href="http://s622.photobucket.com/albums/tt309/adrenalin_photo/?action=view&current=PA300126.jpg" target="_blank"><img src="http://i622.photobucket.com/albums/tt309/adrenalin_photo/PA300126.jpg" border="0" alt="Photobucket"></a>

this is my deck which you can see the unswept cylinder wall of 4 mm.

OK, looks like we have an "export" engine built w/ low compression pistons.

To get 9 to 1 static compression and 8 to 1 dynamic compression ratio, change to flat top pistons and set the combustion chambers at 48 cc.

Can you give us the measurments of the piston dish?
(diameter and depth of the dish)

<a href="http://s622.photobucket.com/albums/tt309/adrenalin_photo/?action=view&current=PB140117.jpg" target="_blank"><img src="http://i622.photobucket.com/albums/tt309/adrenalin_photo/PB140117.jpg" border="0" alt="Photobucket"></a>

my steel (not aluminum) head.. polished by me.

<a href="http://s622.photobucket.com/albums/tt309/adrenalin_photo/?action=view&current=PB140132.jpg" target="_blank"><img src="http://i622.photobucket.com/albums/tt309/adrenalin_photo/PB140132.jpg" border="0" alt="Photobucket"></a>

full view of my steel cylinder head

Lower diameter 54 cm (2.1259")
Upper Diameter 63 cm (2.48")
Height: 5 mm (0.196")

It is a Frustum...