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cylinder pressure

Posted: Fri Oct 09, 2015 7:26 pm
by Budgie
OK so I treated my moggy to a set of new plugs today and did a few tweeks here and there to make sure she runs good for the winter, so checked and corrected the timing, she was 30 degrees out!! but at least all four plugs were in good condition / colour with no real reason to change them , checked and adjusted the points , checked the plug leads and rotor arm, and for good measure I checked the pressure in all four cylinders as you would of course. So my question is, how does 120 in all cylinders come across?

BTW I think the diaphragm on the distributor isn't working as I couldn't see no movement in the distributor or no movement when I blew / sucked the pipe, would this make much of a difference to performance?

Re: cylinder pressure

Posted: Fri Oct 09, 2015 7:49 pm
by PSL184
120 is getting a little on the low side but consistency across all 4 is the most important factor.

Re: cylinder pressure

Posted: Fri Oct 09, 2015 9:12 pm
by bmcecosse
120 is desperately low - did you have all 4 plugs out/hot engine/good battery - and throttle held open? I'm dubious that an engine would run '30 degrees out' - but certainly failed vacuum advance does mean the idling setting will be very wrong. May as well get a complete new 45D dizzy from Accuspark/Powerspark....

Re: cylinder pressure

Posted: Fri Oct 09, 2015 10:37 pm
by Budgie
All plugs were out for the test and just a turn over with the key on each test with a hot engine, no throttle open and all seems to be ticking away fine now after the adjustments although it was / sounded pretty good before hand perhaps a little iffy on the occasional start up and slight under torque but I wouldn't have known unless I corrected it .

Re: cylinder pressure

Posted: Sat Oct 10, 2015 12:07 pm
by bmcecosse
You do need the throttle open (a brick will do the job) and you need to spin it over several times to get the readings....

Re: cylinder pressure

Posted: Sat Oct 10, 2015 5:21 pm
by Budgie
Ah right I'll do that next time as all I did was turn the key for a few seconds each time so perhaps I'm not getting a true reading.....hopefully, although I took her for a spin today and she is performing far better than before I adjusted things as I can start her easier, the key barely turns and she fires up, and she pulls up hills far better with no loss of power and she sounds sweeter!

Re: cylinder pressure

Posted: Sat Oct 10, 2015 8:27 pm
by bmcecosse
Good news !

Re: cylinder pressure

Posted: Sun Oct 11, 2015 4:13 pm
by Budgie
Yeh good news I was well pleased with the results not that I noticed any issues with her before hand apart from the sluggish starting but I'm a bit concerned about the cylinder pressure now until I get the chance to do it again properly! :(

Re: cylinder pressure

Posted: Sun Oct 11, 2015 4:50 pm
by bmcecosse
If it's running well enough -don't worry...

Re: cylinder pressure

Posted: Sun Oct 11, 2015 7:29 pm
by Budgie
True I suppose ...... I don't feel so worried / concerned now then phew !