COMPRESSION READINGS 950CC ENGINE

[mattyb]

does anyone have any idea what readings I should get for my 950cc engine when I compression test it ? I'm assuming that's its a low compression engine ? I can find data for 1098cc but not sure about the 950cc engine ? - hoping that I don't find any cylinder that differs from the others ti any great degree !

cheeany

Matt

[mattyb]

JUST IN FROM THE COLD - READINGS ARE (IF NO 1 IS BACK OF CAR NO 1 - 99 PSI, NO 2 - 99 PSI, NO 3 -109 PSI, NO4 - 109 PSI

ARE THESE ANY GOOD ? THE ONLY INFO I CAN FIND IS FOR 1098CC ENGINE HC = 160lb/in2, 1098cc LC 130lb/in2 ??

IM NOT CONFIDENT THAT MY COMPRESSION TESTER IS WORKING AS IT SHOULD EITHER, AS ONE SET OF RESULTS CAME OUT AT 180 - 190 psi ??[frame][/frame]

[MarkyB]

They sound pretty terrible, did you take all the plugs out and jam the throttle open when doing the tests?
When did you last set the tappets?

[mattyb]

ALL PLUGS OUT AND THROTTLE OPEN - ONLY JUST GOT THE CAR - AS I SAID ONE SET OF READINGS CAME OUT AT 180 - 190 PSI - SO IM REALLY NOT SURE IF MY COMPRESSION TESTER IS OK- THE CARS A 1970 BUT SOMEONE HAS FITTED A GOLDSEAL 950CC.

TAPPETS NOT TOUCHED - ONLY THING I CAN ADD IS THAT THE ENGINE RUNS WITH NO SMOKE AND SOUNDS SPOT ON[frame][/frame]

[liammonty]

To be honest, if it runs nicely, doesn't smoke, and sounds OK, then I'd stop trying to find something to worry about! I don't know figures for the 948, as they're not in the workshop manual, but a 1098 low compression is 130 psi (as you said) and the standard high compression should be 160 psi. You should be able to tell whether your engine is (or should be!) high or low compression from the engine number I think, unless they're different on Gold Seals- usually there's an 'H' or 'L' in the number. Assuming it's HC, I reckon you'd hope for 140-150 psi if it was newish, though it's difficult to 'guesstimate' what the compression should be, as the cam's a little different to the 1098, and the head and piston volumes are different etc etc.

Was the engine warm when you did the test? That would probably make a fair difference. Also, did you turn the engine over a few times (maybe 10 as an example) in order to let the gauge get up to an accurate reading? If you can't figure it out, but it's running OK, then just drive it. The best engines I've had have always been the old knackered ones that just seem to keep on running and running...

[mattyb]

fools rush in... !

engine was stone cold ! - engine code is 8g9rl47703md = so a low compression engine ? been trying to decode the number for a while - agree that I need to see how the car feels once its road worthy ( as per my post re my late 4 door with this 950cc engine)

[bmcecosse]

Indeed - you should do the test with a nice hot engine - so the oil is thin and the engine spins over easily, and the battery will be warm and nicely charged. So -do a ten mile thrash and then run the test immediately. But I'm guessing since they are all much the same - there's no big problem.

[StaffsMoggie]

Just don't do what a mate did. He took one plug out, screwed a compression gauge in and turned the key. As he had left the ignition connected and the rest of the plugs in place the engine started up and blew the gauge to bits...

HeeHeeHee