Richard Jenkins
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| posted on 15/4/06 at 08:36 PM |
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X/flow compression check
Anyone know what pressures should be expected when doing a compression check on a 1300 x/flow (built to 750MC spec)?
I'm getting:
no.1 - 140psi
no.2 - 140psi
no.3 - 130psi
no.4 - 120 psi
cheers
RJ
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Fozzie
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| posted on 15/4/06 at 09:05 PM |
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Rich, rule of thumb is no more than 10% difference between any cylinder.
HTH Fozzie
'Racing is Life!...anything before or after is just waiting'....Steve McQueen
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wicket
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| posted on 15/4/06 at 10:07 PM |
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Haynes says 142 to 170 psi
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perksy
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| posted on 16/4/06 at 08:55 AM |
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Try a small amount of engine oil down each bore and re-check readings.
Also make sure throttle is wide open.
HTH
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britishtrident
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| posted on 16/4/06 at 09:24 AM |
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If I bought an old 1300 escort that gave those compressions I would be happy but in a racer engine too much variation.
First thing to do is check the valve clearances, after that rather than squirting oil down the bores a little Redex down the bores and soak for 24hrs
plus give it a spin over another squirt in each cylinder then retest -- but only a little as because of the bowl in piston design X flos can give
misleading results to the oil in cylinder compression test.
To get a proper idea of wether the problems is piston/bores or valves a cylinder leak down test gives better results.
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Richard Jenkins
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| posted on 16/4/06 at 08:12 PM |
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Probably should have checked for reply's this morning before taking the head off.....
Thanks for the info guys, but I'll have to put it into action when I've put everything back together.
Didn't know about having the throttle wide open, so all those pressures were with it shut. Also didn't put any oil / Redex in before
testing, so I guess I had some pretty meaningless results?
The exhaust valve on no.4 had oil down the stem and around the seat, but the others looked ok. I'll change the seals but not sure what else
could have let oil in. The seals were halfway up the stems and not a snug fit on the top of the valve guide. The guides (& just about everything
else on the engine) have done less than 3 hours from new
The bores all looked ok with no scoring or marks.
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rusty nuts
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| posted on 17/4/06 at 08:03 AM |
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Cross flow valve stem oil seals have never been the best of fits. They are more like an umbrellathat just sits on the valve stem and deflects oil away
from the guide. Think it may be possible to use seals from another engine that would be a tight fit over the guide and the valve stem ? check your
local engine reconditioners they may help. Think this has been covered in the past and may be worth a search?
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