1946 Farmall B rebuild no compressio

Murray46b · Aug 16, 2015

Hi All,

Here is my problem. I have a 1946 Farmall B. It ran good but had a cracked water jacket. I found a good block. Bought a gasket set and sleeves and pistons and rings set. Swappped it all out. Made sure cam and crank single marks aligned. Have got good fire.
My problem is I have no compression except on number 3 cylinder. I took head back off. Honed cylinders again. Cleaned well with brake cleaner. Put all back together. Now I have compression on 1 and 4 cylinders and zero comppression on 2 and 3.
Can someone please tell me what is going on???? I am at a total loss here.

John

Angle Iron · Aug 16, 2015

(quoted from post at 10:40:37 08/16/15) Hi All,

Here is my problem. I have a 1946 Farmall B. It ran good but had a cracked water jacket. I found a good block. Bought a gasket set and sleeves and pistons and rings set. Swappped it all out. Made sure cam and crank single marks aligned. Have got good fire.
My problem is I have no compression except on number 3 cylinder. I took head back off. Honed cylinders again. Cleaned well with brake cleaner. Put all back together. Now I have compression on 1 and 4 cylinders and zero comppression on 2 and 3.
Can someone please tell me what is going on???? I am at a total loss here.

Did you set the valve clearance after you did the other work?

John

Murray46b · Aug 16, 2015

No I did nothing with valves. How do I set/check valve clearance?

Thanks

deene · Aug 16, 2015

since it has changed on you like that I would be inclined to think camshaft out of time or perhaps if the drive gear or driven gear are keyed that one or the other might be slipping on you causing the valves to not open correctly..i would look into the bores with the spark plugs out and watch the valves opening and closing on each cylinder to see if the timing on piston rising in relation to intake opening and closing and exhaust staying shut to tdc is remotely close..also check valve lash and make sure you don't have them to tight so they don't close all the way..someplace to start anyway hope this helps

deene · Aug 16, 2015

feeler guage between rocker arm and valve stem I don't have the clearances you need but id start with 22 thousandths or .022 and go from there.. this is pretty big for most stuff and you should have plenty of room between piston and valve but set them at this and roll over with hand crank instead of starter and make sure that gets you some compression without jamming things together....someone here will surely chime in on the correct clearance for you but this should get you started

David G · Aug 16, 2015

Set the valves, get a manual, the valves HAVE to be set on the low place of the cam.

rustred · Aug 16, 2015

thats pretty scary, how do expect it to run,each engine has spec's to follow. the valves must be set correctly to .014 when hot. you set then with each cyl. on top dead centre of the compression stroke. following the firing order, 1342.
never heard of honing cyl's with pistons in bore. also if the sleeves are new why hone them as nothing will compare to the factory crosshatch pattern. did you stagger the ring gaps? as need to do that. are rings installed the correct way?
you need the timing set on the money also.
after run for an hr. you need head retorqued and valves reset.

Murray46b · Aug 16, 2015

(quoted from post at 11:55:53 08/16/15) thats pretty scary, how do expect it to run,each engine has spec's to follow. the valves must be set correctly to .014 when hot. you set then with each cyl. on top dead centre of the compression stroke. following the firing order, 1342.
never heard of honing cyl's with pistons in bore. also if the sleeves are new why hone them as nothing will compare to the factory crosshatch pattern. did you stagger the ring gaps? as need to do that. are rings installed the correct way?
you need the timing set on the money also.
after run for an hr. you need head retorqued and valves reset.

I never took the head apart. Same valve trane. Same push rods. Same cam and lifters. Why would I need to change my valve settings ?

Patsdeere · Aug 16, 2015

They would be worth a check. No two blocks
are the same. Slight differences in where
things got bored could make a slight
difference.

old · Aug 16, 2015

Very simple. Any time the head has been taken off you have to readjust the valves since no 2 head gasket are the exact same and you can not get every thing back on the exact same way it came off since nothing if perfect

Murray46b · Aug 16, 2015

(quoted from post at 12:19:44 08/16/15) Very simple. Any time the head has been taken off you have to readjust the valves since no 2 head gasket are the exact same and you can not get every thing back on the exact same way it came off since nothing if perfect

That makes sense. The valves need to be set then. Thanks

old · Aug 16, 2015

Yep no matter what if you remove a head be it one time or ten times each time you have to adjust the valves or they will not be what they should be set at and cause all sorts of oddproblems

David G · Aug 16, 2015

Did you hone cylinders with pistons in, if so I would disassemble completely, reclean and reassemble.

Murray46b · Aug 16, 2015

Thanks to all who commented!!!!!! It was my valvle clearance. Manual states .014. Set the balves and it fired right up.
You all know what your talking about!!

1946 Farmall B rebuild no compressio

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