[DeTomaso] 302 diagnosis

[Asa Jay Laughton]

Dennis,

Yea, that sounds pretty darn low.  The best thing to do is a cylinder 
leak down test to see if it's rings or valves.  I have to wonder and 
throw this out though.  What about valve timing?  If the cam is timed 
one or two teeth off the wrong direction, it might cause a similar 
problem; having the valves open when you don't really want them.  But 
I'm probably just putting out false hope.

When I got done with the last 351C rebuild for the Mach I, my 
compressions was near 200.  If you are getting a high of 75, I think 
you're in for pulling things apart.  Make sure you are blocking the 
throttle plates wide open when you test, disconnecting the coil, 
cranking a minimum of three times, etc.

Are all cylinders low like this?
Are any adjacent cylinders the same?
Any water in the oil?
Any oil in the water?
Any popping out the intake or exhaust?
What's the crankcase pressure like after it warms up?

Let us know more,
Asa Jay

Asa Jay Laughton, MSgt, USAFR, Retired

& Shelley Marie
Spokane, WA

1973 Pantera L 5533
[ASASCAT]
    
******************************     
http://www.asajay.com
http://www.351c.info
  



dyogi wrote:
> Need some help with the goose's 302. I've been having a problem with the
> goose lately, it starts and idles and revs up great but with low vacuum
> reading (about 10hg, I have a .456 lift/218 duration cam installed). As the
> engine reaches normal operating temperatures, the idle drops until the
> engine dies. If I increase the throttle the engine will stay running. It
> will start right back up but will not idle until cool. I ran a compression
> test today. Not sure what normal reading should be but they seem low and are
> not consistent running about 50-75psi. I have to run the compression test
> again after squirting some oil into the cylinders. If the readings stay the
> same I am suspecting that I have valve problems. Am I on the right track? I
> have swapped out 3 different ignition systems and three different
> carburetors with no change which is why I ran the compression test.
>
>
>
> Aloha from Hawaii,
>
> Dennis
>
>  
>
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