Plug colours & compression test

[Lebro]

Decided to check on my plugs yesterday, I had a feeling that one carb was a bit lean compared to the other (a bit "chuggy" before fully warmed up).

 

 

 

It looked to me like the rear two were a tad richer, but really not that bad.

While the plugs were out, I thought I may as well do a compression check:

 

1 - 151 PSI 2 - 161 PSI 3 - 126 PSI 4 - 145 PSI this was on a cold engine last run the day before.

 

Bit concerned about No. 3. The engine is as Mr Triumph built it sometime prior to 1970 (FRE) so must be nearing the time for a rebuild. Is this drop likely to be first signs of valve recession, or leaky rings.

Car does not smoke, or burn oil, but does have a "tap" which increases with load, but goes away when engine warmed up - thinking piston slap there.

 

Comments (polite ones) appreciated.

 

Bob.

 

 

[marki]

Hi Bob.

I would do the test again but hot, if the readings are still out put a drop of oil in the bores and test again. If the readings come up it's rings if not valves.

Good luck Mark.

[Nigel Triumph]

Hi Bob.

I would do the test again but hot, if the readings are still out put a drop of oil in the bores and test again. If the readings come up it's rings if not valves.

Good luck Mark.

 

Good advice from Mark to do the compression test hot. Also remember to have the throttles wide open while cranking for the compression test.

 

I would expect a healthy engine to show somewhere around 140-150psi hot, with no more than 10% difference between cylinders. The difference between cylinders matters as much at the actual figures. Looks like No.3 could be a bit down on compression but the hot test figures without then with a few drops of oil will show more.

 

 

Nigel

[Lebro]

Thanks guys, will do.

 

Bob.