Compression Test

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Anonymous

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After my car recently stoped with a violent bang (from the dizzy gear being no more) i run a compression test.

the readings were

Cyl - psi
1) - 210
2) - 200
3) - 200
4) - 190
5) - 200

Is there anything to worry about with cly 1 & 2 being higher and lower than the rest?

Cheers

Simon
 
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I can't do nothin for you man.

Check lash, pushrod length, and understand that the compressions look very high. Advancing the cam may help remove the extra pressure. It may be the cam is too big, and rather than ditch it, just degree it until it works. You should condiser 185 as being about it on even high grade super plus with 98 octane. Old HO's ran 185 psi or so with 10.7:1 comp, and the cam was 300 duration with 500 thou lift.

The cam is under huge load with intense cam profiles. I'd be looking at dyno tunning to find the advance of the cam that works best.

I don't know much else. The distributor bush free play and lubrication are important on hard worked Henries. They don't get enough oil there.

Posts by addo, alloydave and backlash cover the distributor gear.

You must pull the cam and check things. There are not enough bearings on Ford cams, and I'd be wanting to make sure there is no issue with the servicability.
 
Simon,
The compression figures you have quoted look to be a bit too high.
But that could be down to gauge variation.
One thing I have learned is not to trust one gauge as being the gospell on compression tests.
So long as the reading are near the quoted figures.
The variation in the figures, gives a better indication of engine condition.
F.Y.I
Once the other areas of engine operation, noises and oil pressure are checked and you are satisfied that there is no major engine problems.
A compression test is carried out and the figures examined.
As I said the outright figures and the variation are checked.
The figures quoted here are what I would consider to be on the limit of around a ten percent variation.
Ten percent is the nominal figure that most manufacturers that I have consulted with use within the specification for engine condition.
With this engine I would say to repair it with the idea that it may require attention (rebuilding/replacment) in the future.
And to answer that question.
No I dont know how far in the future.
Engine and vehicle life is determined by its use and service history.
Hope this helps and I didnt sound too much like a smart a**e.
Noel.
 
Engine and vehicle life is determined by its use and service history.
That sounds like a line the RACV might feed customers who are being unreasonable!

As to the gear, Crow's DG2/DG-2A cover most non-roller applications. Pay up to $75 for one.

Cheers, Adam.
 
Thanks,

I might get it looked at on a dyno. Might save me alot of time and money in the long run.

$75 is all right if i dont have to pull the bloody dizzy out again for a while :)

cheers

simon
 
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