Farmall A Head Question

[papetk]

I’m rebuilding the head on my 47 Farmall A. I bought new valve guide sleeves but they are a different design than what was originally there. There’s a collar on the original ones that set the high off the head. The new ones have no collar. Overall height, inner and outer diameters are the same. Do I just measure the height off the head to be the same as the originals? Are these fine to use? Or, do I need to source other ones?

 

[Mrfred54]

I have used those on my head. No issues

 

[Mrfred54]

Also, I did not use valve seals. Figured a little oil on the valve stems for as much as I use the tractor would not hurt a thing. I does smoke a little blue at every start up but that doesn't bother me

 

[rustred]

I’m rebuilding the head on my 47 Farmall A. I bought new valve guide sleeves but they are a different design than what was originally there. There’s a collar on the original ones that set the high off the head. The new ones have no collar. Overall height, inner and outer diameters are the same. Do I just measure the height off the head to be the same as the originals? Are these fine to use? Or, do I need to source other ones?View attachment 128462

They are a cheap reproduction , you have no choice but to measure the top end. Plus u see how the original one is tapered , that is why they don’t use valve stem seals , the new one is iffy. Might need seals

 

[Fritz Maurer]

You better be prepared to grind the valves and seats....they may be too far out to lap.....the valve is now gonna land straight on a crooked seat that may not be concentric with the new guide.

The worn-out guides allowed for a little misalignment.

 

[rustred]

I just presumed the valves and seats would be reground or replaced as he said a head rebuild. Yes forget the lapping totally obsolete.

 

[Mrfred54]

I had the machine shop install them guides and then new valves and ground the seats

 

[papetk]

I did buy new valves and springs. With the new sleeves, am I required to grind the valves or is it possible lapping may do the trick?

 

[Fritz Maurer]

I did buy new valves and springs. With the new sleeves, am I required to grind the valves or is it possible lapping may do the trick?

It depends on how far out of misalignment the new guides put the valve in relation to the seat.

If you were to attempt lapping, it would be best to start out with at least one flat surface, i.e. a new valve or a refaced valve.

But if a number of valves are too far out , you will be charged the same price at the machine shop whether for one valve or eight because they are going to reseat the valves that you just lapped.

If you did buy new valves, you don't need to do anything to them. The idea is to line the seat up with the valve by removing metal from the seat until it makes contact with the valve a full 360º . You are literally moving the seat over to the center of the valve.

Can't hurt to try , though. It will become apparent right away if it's just a matter of skinning off some rust or have to go to the shop.

 

[rustred]

I did buy new valves and springs. With the new sleeves, am I required to grind the valves or is it possible lapping may do the trick?

This is machine shop work. Once guides are replaced the seats need to be ground or replaced also. Depending on how bad they are. Even the new valves are put in the machine and checked with a slight resurface. The old springs are also checked for tension. Get lapping out of your head as no machine shop does that. Only these backyard guys do that , but no way is it the proper thing to do. The seat must be ground and have the correct width and be positioned properly on the valve face. Seat is 45 degrees. Then you have 60 and 30 degree stones to do that.

 

[rustred]

Here is what you want the seat to look like. you see that black dot on the seat,.. that is the 45 degree seat width below is 60 degree angle and the top at head is the 30 degree angle. its hard to see the seat location on the valve face , its that line in the middle of the face. plus there is an interference angle of one degree between them , this has replaced lapping valves for decades and decades. plus head shops know all this. you want a good job it has to be done properly. and get all max power from the engine . show a pic of them seats on your head, as if they are too low they will need to be replaced as i did here.

 

[560Dennis]

I have the shop put in some steel valve seats and get the valve height correct. How your rocker arms worn down ?

 

[Fritz Maurer]

If possible, press the guides in. You can of course hammer them in, but the probability is better that a burr will form on the inside that will have to be removed.

 

[560Dennis]

If possible, press the guides in. You can of course hammer them in, but the probability is better that a burr will form on the inside that will have to be removed.

Hammer them in, what size hammer do you use ?

 

[Fritz Maurer]

Hammer them in, what size hammer do you use ?

Probably as big as the one shown in the picture, but i really didn't like it. Im finding out that these finished guides, whatever country they come from, are sometimes oversized OD slightly and go in very hard. I began measuring them to see what the problem was, I've seen them as high as .0005" over the. 0003 " required for a driving fit, for a total of nearly .001" oversize which is way too much. Never had one break while hammering it in, but then I didn't use that method very long. It is much smoother to press them in against pre- made depth stop.

Had a couple 5.7 Diesel heads a couple decades ago, the guides shrunk when installed and nearly all of them needed to be finish reamed.....which naturally takes out the oil spiral. This seems to have been going on for a while.

 

[Janicholson]

I’m rebuilding the head on my 47 Farmall A. I bought new valve guide sleeves but they are a different design than what was originally there. There’s a collar on the original ones that set the high off the head. The new ones have no collar. Overall height, inner and outer diameters are the same. Do I just measure the height off the head to be the same as the originals? Are these fine to use? Or, do I need to source other ones?View attachment 128462

Measure the height of the upper portion carefully, find a piece of pipe (maybe 1/2") and cut a chunk off at that length. (a lathe is handy for that, or a bit of filing) use this as a stop for instillation by putting it over the new guide when it is 1/2 the way in place. then drive the guide until it is flush with the stop. Easy and accurate. Jim