JD 350 Straight Diesel - What Are Y'all Seeing for Compression PSI?

[bulletpruf]

Decided to replace the injectors (went with Stanadyne) on my 67 JD 350 Straight and while I was at it, I did a compression test. The Service Manual says that the minimum is 300 psi and all should be within 50 psi of each other.

I did adjust the valves prior to the compression test; one was tight and several were quite loose. Would have been interesting to do the compression test before and after valve adjustment to see if I gained any compression, but I just did it afterwards.

I ended up with 400, 390, and 380, which is well above the minimum, but I'm not sure what reading you get on a low-hour engine.

Anyone else have their numbers?

[LeonardL]

Your numbers are great dude! A brand new engine might be a bit higher PSI than what you have but it wouldn't be much. And even then once it breaks in they would settle to about what you have. Looks good to me!!

[bulletpruf]

Your numbers are great dude! A brand new engine might be a bit higher PSI than what you have but it wouldn't be much. And even then once it breaks in they would settle to about what you have. Looks good to me!!

Thanks, Leonard. Appreciate the feedback.

Scott

[dabear3428]

Are you having any issues with the engine?
those numbers look good, but how is the engine working?

[bulletpruf]

Are you having any issues with the engine?
those numbers look good, but how is the engine working?

It does not run great at low rpm. Hopefully the new injectors and freshly adjusted valves will clear that up. I also need to check the timing on the injection pump; haven't done that yet.

[CatD8RII]

Older Deere 3 cylinders (152 and 164) have a little lope to them at idle, especially if you go below 800 RPM. Just the nature of the beast.

[bulletpruf]

Ok, thanks for the info. It does clean up at higher rpms.

[Stan Disbrow]

Hi,

Yep. The various 152 and 164 engines I have had all loped at low idle as well. even after IP rebuilds and new injectors.

The current 174 Turbo does not. But the old ones spanned from 1966 to 1978 and the 174 is from 2008. So plenty of changes involved beyond just the displacement and the turbo. Such as the mechanical IP sports a solenoid on the bottom that adjusts it based on a thermal switch in the water jacket.

Stan

[bulletpruf]

Hi,

Yep. The various 152 and 164 engines I have had all loped at low idle as well. even after IP rebuilds and new injectors.

The current 174 Turbo does not. But the old ones spanned from 1966 to 1978 and the 174 is from 2008. So plenty of changes involved beyond just the displacement and the turbo. Such as the mechanical IP sports a solenoid on the bottom that adjusts it based on a thermal switch in the water jacket.

Stan

Ok, it will be interesting to see how she runs when I fire her up again. Just need to finish upgrading the fuel return line and my t-boots are supposed to be here today.

Thanks