Compression-how low?

[fitzms]

Hi fellas,89 225 jonno,just honed and all new rings,I heard that you should not have any more than 15 psi variation between cylinders which I now do not have since overhaul but the compressin in all cylinders is still only a little under 100 psi.I would hve thought it higher after the work done is this ok for this motor or should it be higher.The mechanic said these motors are known to be a relatively low compression motor.

 

[Solittle]

Re: Compression-how low?

fitz - I wouldn't worry about readings at this point. Do a careful breakin then reun it for 20 or so hours and then check again.

 

[rabidfish]

Re: Compression-how low?

Break it in long & slow. Do NOT use a synthetic oil for break-in... Also check the spark at each plug/cylinder to ensure no double firing. Those engine also had problems sucking the reed gasket out from behind the reed cage. You may want to double check that if the engine idles rough or if it lean sneezes. Compression isn't a great test for those engine, partly because they had lower compression that most other engines.

 

[rodbolt]

Re: Compression-how low?

hello<br /> the first one I ever tested read 80 psi acrossed the board, so I went and borrowed another techs gauge and it read the same. somewher around that number is where most big OMC loopers ran,<br /> if they are even, ya done good for now