soviethoss Posted December 21, 2016 Share Posted December 21, 2016 just a quick one been doing up a Austin eight AP MILITARY TOURER..and nearly finished .but does anyone know what cylinder compression should be wont start only go 60 40 40 40 psi cheers hoss:nut: Quote Link to comment Share on other sites More sharing options...
0 Richard Farrant Posted December 21, 2016 Share Posted December 21, 2016 You don't say if you have worked on the engine. If it has been standing for years then the bores could be dry, try putting a drop of oil in each plug hole. Also ensure throttle is wide open when doing compression check. Quote Link to comment Share on other sites More sharing options...
0 soviethoss Posted December 21, 2016 Author Share Posted December 21, 2016 thank you for the info ..no I have not worked on the engine it was in the car when I got it about a year ago all seems to be ok but wont start I think this is because of low compression ..done what you said but still only 60 max its the pressure I need to know what a Austin eight should be cheers steve Quote Link to comment Share on other sites More sharing options...
0 Pete Ashby Posted December 21, 2016 Share Posted December 21, 2016 Anything between 85 to 100 psi on this size engine would be about right, on a warm engine with the plugs out and on the starter motor with a fully charged battery and as Richard notes throttle wide open. Variation between cylinders something in the region of +/- 10psi. Pete Quote Link to comment Share on other sites More sharing options...
0 Richard Farrant Posted December 21, 2016 Share Posted December 21, 2016 thank you for the info ..no I have not worked on the engine it was in the car when I got it about a year ago all seems to be ok but wont start I think this is because of low compression ..done what you said but still only 60 max its the pressure I need to know what a Austin eight should be cheers steve Steve, OK, so if you have not had the engine apart, I would say you need to remove the head and valves for a start. Side valves are known to stick on standing and at the least you will need to decoke and check the valves and seats, re-cutting seats and re-facing valves then lapping in. Also check the bores for wear. Before refitting the head, ensure it is true across the face and not warped. I did rebuild one of these engines a few years ago. regards, Richard Quote Link to comment Share on other sites More sharing options...
0 Sean N Posted December 21, 2016 Share Posted December 21, 2016 Steve, To recap what Richard said, make sure you have the throttle open. Test the compression in the same conditions dry and with a teaspoon of oil in each bore. If there is no change in compression, you either have very poor bores / rings, so poor the oil won't seal them, or you have a valve or gasket problem. It's likely as you're testing cold the compression will be low anyway, but 40 - 60 sounds very low. I'm not an Austin 8 expert but from what I've heard I'd expect more in the 90 - 120 range depending on exact engine / head spec. Having said that, it would be worth going through spark, fuel, timing again just to make sure. Given it's such a simple engine if you're suspicious you could just whip the head off and have a look for problems, but if you don't want to do that and you have a compressor available you could invest £20 in a cheap leakdown tester of eBay, which would give you more information. Quote Link to comment Share on other sites More sharing options...
0 Sean N Posted December 21, 2016 Share Posted December 21, 2016 (edited) Steve,Given it's such a simple engine if you're suspicious you could just whip the head off and have a look for problems. Anything between 85 to 100 psi on this size engine would be about right Pete Steve,OK, so if you have not had the engine apart, I would say you need to remove the head and valves for a start Regards, Richard Sorry Richard, Pete, cross-post! I was thinking maybe stuck valves as well, particularly if oil in the bores isn't sealing it. Edited December 21, 2016 by Sean N Quote Link to comment Share on other sites More sharing options...
0 soviethoss Posted December 21, 2016 Author Share Posted December 21, 2016 thank you all for the info.. after a few days and some help still only got it to fire but not run ..so I will try head removal see whats there and if I get it sorted I will let you know ps thank you for your help cheers steve Quote Link to comment Share on other sites More sharing options...
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soviethoss
just a quick one been doing up a Austin eight AP MILITARY TOURER..and nearly finished .but does anyone know what cylinder compression should be wont start only go 60 40 40 40 psi cheers hoss:nut:
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