Adrian Posted September 5, 2017 Report Share Posted September 5, 2017 Hi all Now I know this isn't right but I've cranked the engine by hand (engine is out) just to check compression consistency (I've only just got a tester). So I know I can't achieve proper compression (my arm only works so fast) but noted that I got around 70 in 6, 5 and 3. 4 was 50 and 1 and 2 was 20-30. Even by hand that seems to be a big variation. The engine ticked over quite nicely before I took it out with no oil burning, etc. I haven't check the valve clearances as yet. The car history seems to be a replacement engine was put in around 1990 at the same time the speedo was zeroed so basically the car has done 23K in that period. I know it tends to be a house of cards when dealing with this sort of thing and have enjoyed (ish) learning but I really don't want to be messing with piston rings - particularly as the sump has been on twice already, thanks to a stripped thread! If I read the manual right, compression should be 140ish? So I assume muscle power has only achieved 50% and so 6, 5 and 3 are OK and 1, 2 and 4 are lacking. I'm hoping it may be valve settings. Any thoughts? Many thanks and looking forward to the 17th. Link to comment Share on other sites More sharing options...
Colin Lindsay Posted September 5, 2017 Report Share Posted September 5, 2017 To be honest I don't think you'll get anyway near the proper compression using only muscle power! If the engine is running ok before being taken out I'd try a compression test again once it's refitted; there's no point in initiating repairs based on an incorrect assessment unless you just want to be sure and refurbish it anyway, which going by your post, I don't think you want. If nothing else, can you rig up a starter connected directly to a battery to get it up to a proper speed for testing? It might give a more realistic reading and allay your fears somewhat. Link to comment Share on other sites More sharing options...
Pete Lewis Posted September 5, 2017 Report Share Posted September 5, 2017 yes think i echo colins thoughts, and were the throttles open , any restriction will reduce the readings , especially hand cranking, if the front carb was shut then you get low reading if the carbs are off , well more shreaded wheat may help !!! Pete Link to comment Share on other sites More sharing options...
Adrian Posted September 5, 2017 Author Report Share Posted September 5, 2017 That's good to know - I can carry on as planned! No carbs or manifold on. I knew I wouldn't get anywhere near - just wondered about the observed variation. Link to comment Share on other sites More sharing options...
JohnD Posted September 5, 2017 Report Share Posted September 5, 2017 It's impossible to say, this is an acceptable pressure, this is not, as the gushes are uncalibrated. They are invaluable to compare the bores in a block, or else if you have a known ( believed?) good engine to compare with that. Don't omit to do the oil test: teaspoonful down the p!ug hole after doing the test 'dry'. This will improve even poor ring sealing, but have no effect on valve seal, so diagnostic. John Link to comment Share on other sites More sharing options...
Pete Lewis Posted September 5, 2017 Report Share Posted September 5, 2017 was dreaming about making a clear U tubed water filled manometer to compare the swept volume condition but reckon would need one as high as the house Hmmm !!!! back to compressions , one good stroke from btc to tdc and compare , will be low figures but only takes half a turn of the crank which is an easier effort if by hand and 3 shredded wheats rather than try to turn over and over enough to get the best readings just a ramble Pete Link to comment Share on other sites More sharing options...
JohnD Posted September 5, 2017 Report Share Posted September 5, 2017 Swept volume is a dimensional calculation, if you have the head off, but if you wanted a water manometer type device, the height will depend on the diameter of the tubing. But a better design would be, fill the bore with a liquid at BDC, stick a hose in the plug hole and turn the crank to TDC, catching the liquid INA measuring jug. Don't forget to empty the hose into the jug! John Link to comment Share on other sites More sharing options...
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