DeTomaso Mailing List: April 2001, Message #192

At 14:46 04/05/2001 -0400, Thomas Tornblom wrote:
>Here's a picture of cylinder 8 - 5 (in that order) plugs:
>http://www.detomaso.nu/~thomast/plugs.jpeg

Looks like 7 is running rich.

>Right after start it feels as if it doesn't run on all cylinders.
>
>I took a compression test:
>
>cyl	comp (bar)
>5	8.0
>6	7.8		
>7	8.5
>8	7.5

Was the compression test done cold or hot?
If cold, hmmmm.
If hot, then it's possible your having a compression problem that is
sealing the cylinder once it's warm.  Do both a hot and a cold compression
test and let us know the results.

>This is what the head looked like when I replaced the gasket:
>http://www.detomaso.nu/~thomast/efi/head-left.jpeg

Yup, same cylinder doing the same thing before.  Too rich, not getting
clean burn, etc.

I'm beginning to suspect the lifters (why oh why didn't I replace them when I 
>had the intake off...).

You can still check this with the engine assembled.  You just need a dial
indicator and something to hold it solid to the valve or pushrod with.
Just mount the dial indicator agains the valve or pushrod and rotate the
engine watching the overall lift.  Compare to other cylinders.  This will
generally let you know if a cam lobe is going bad, however, I tend to thing
the problem would be "permanent" and not go away when warm.

The only other assumption might be that the piston has excessive clearance
in the bore, causing lower compression when cold and better compression
when warm.  I do find it odd though that number 7 appears to have the
greatest compression.

Have you done a cylinder leak-down test?  That might provide some clues as
well.


>I pulled the left valve cover last night to verify that the rockers at least 
>seems to move properly. I noticed that the oil deflectors in the rockers
are not 
>mounted the same way as in the service manual:
>
>See:
>http://www.detomaso.nu/~thomast/deflector1.jpeg

I think you are correct, I think the deflectors are mounted backwards in
that photo.  I'm not sure, as all mine are now roller rockers and don't use
the deflectors.

Asa Jay

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