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Dadofour's Avatar
 
Join Date: Dec 2003
Location: Middletown, NJ 07748
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Stock 3.2 Motronic Deck Height Question

I am rebuilding a stock 3.2. The P&C's came from another 3.2 with less miles and better P&C's. I will be installing 964 cams.

I have measured the deck height using the solder method on both sides of the piston on the axis of the crank.

On every cyclinder the side with the higher piston side is a smaller measurement. My range is from 1.168mm to 1.52mm.

Cyl hi side lo side

1 1.42mm 1.52mm
2 1.17mm 1.19mm
3 1.27mm 1.42mm
4 1.27mm 1.52mm
5 1.27mm 1.52mm
6 1.27mm 1.47mm

I am going to remeasure the cylinders that are not consistent with the rest, but with cylinders out side the .9mm-1.2mm recommended deck height, can I remove the .25mm gasket to get these into spec?

If not, what are my options?

Thanks

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1984 911 Viper Green Track Car - Parted out to fund
1993 BMW 325is Spec E36 Race Car

Last edited by Dadofour; 01-08-2006 at 03:16 PM..
Old 01-08-2006, 03:07 PM
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I would check the cylinder heights and if they are even, deck the case spigots. This will kill two birds with one stone.
1. You get a deck height closer to ideal.
2. You'll have a nice square and even foundation for the top end of the motor.
-Chris
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Old 01-08-2006, 07:33 PM
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Chris,

Is "decking the case spigots" the same as machining the spigot openings down to get a consistent cylinder height?

If so, can this be done after the bottom has been sealed, without having to split the case again?

Thanks
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1984 911 Viper Green Track Car - Parted out to fund
1993 BMW 325is Spec E36 Race Car
Old 01-09-2006, 05:10 PM
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Quote:
Originally posted by Dadofour
Chris,

Is "decking the case spigots" the same as machining the spigot openings down to get a consistent cylinder height?
Yes.

Quote:

If so, can this be done after the bottom has been sealed, without having to split the case again?
Thanks
I'm afraid not.

I wouldn't worry about the deck height now. There are worse things than having the factory deck height.
-Chris
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Old 01-09-2006, 05:57 PM
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I am still not really sure whether I will have detonation issues because my height seems to be above the recommended 1.2mm.

Any thoughts. I want this engine for almost exclusive track use, so better performance is the key, and I have a functioning motor in the car. I want to do it right.

Thanks for all of your help.
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1984 911 Viper Green Track Car - Parted out to fund
1993 BMW 325is Spec E36 Race Car
Old 01-09-2006, 06:02 PM
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Spoke with the machinist who is doing work on this engine for me.

He feels that for a stock rebuild that my measurements are well within good limits. His greatest concern was with the low range not the high.

I am moving forward with the head and cam tower assembly.
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Than
My Track Schedule

1984 911 Viper Green Track Car - Parted out to fund
1993 BMW 325is Spec E36 Race Car
Old 01-12-2006, 04:32 PM
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Interesting, I know it's an older forum but good information.

alex
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Old 02-14-2007, 08:38 PM
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As an aside, I finished that engine in the spring of 2006 and strted running the engine in July. This engine kicks ass. I have not had it dynoed yet, but it is very, very peppy.

T

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1984 911 Viper Green Track Car - Parted out to fund
1993 BMW 325is Spec E36 Race Car
Old 02-15-2007, 06:03 PM
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