Farmall H Compression

[Rein_Quest]

So I have an H. I believe it s gas because it looks like a standard manifold and only one tank but the carb and hood do look like they re off a distillate.

I got 75-55-55-55; back to front. I m wondering if I did the test wrong. I think we only wound it twice. It runs fair and doesn t smoke. Only starting issues have been a damp magneto otherwise it s been great starter.

I guess the tester could be bad. It s only been used on a lawn tractor and the H. The rider didn t run and supposedly tested 25 but the H is my personal first test so I wonder if I screwed up.

 

[rustred]

you need to have the throttle at least 1/2 advanced so the butterfly is open. then do the test on a warm engine. you need 5 puff's or revolutions per cyl. the first two will pretty much be maximum. you will get a small increase after that. do all cyl's the same with 5 revolutions. not crank till the guage stop moving as some people say. the front is #1 cyl. so why not start with it. those 55 lb ones are low. recheck and post.

 

[NawlensGator]

I did a compression check on a C123 engine (IH 140) and all cylinders were between 155 and 160 psig. The engine smoked bad, the spark plugs were always fouled (wet), and when we rebuilt it the sleeves were worn and needed replacing. Point is, compression checks can be good, but the engine still needs rebuilding.

 

[Rein_Quest]

Thanks I ll retest this coming weekend. I don t live on the property where it s kept. When you say warm should it be on the Run indicator of the thermostat? Also would it affect anything if the throttle is above half? Because I know it didn t have that up. Habit is to short it at low idle.

I appreciate the other advice about what sounds like good compression but still needed work. Right now it doesn t smoke and the plugs don t seem fouled. Maybe I m just too used to the M but I was feeling like I wasn t getting the HP so I was checking the compression. Could need the mag timing tuned but I ve never done that before.

 

[BarnyardEngineering]

With those compression numbers it should not start without being pulled down the road by another tractor.

Personally I've never noticed much of a difference with throttle open or closed, other plugs in or out, but two revolutions of the engine is NOT enough to get an accurate compression reading.

 

[used red MN]

To make darn sure it you should check the valve lash first. I believe the spec is 0.017 in. for both
in. and ex. It is understandable that if a valve is being held slightly off it seat the compression in
that cylinder will be low.

 

[Rein_Quest]

That sounds right, I m know that number is in the manual. I ve been wondering how easy that is to check because I m pretty sure my hand crank is froze up.

 

[Rein_Quest]

I re-ran the test and all were 75-80.

I did not have a chance to check the clearances under the valve cover. Still wondering how easy that is if you can t use the hand crank to advance it.

My dad would say "it starts easy, it does what we want it to, it s good".

I think this might be an indicator to plan for a fall season and do a rebuild.

What s your advice?