valve question

[larry harding]

i bought a used engine a while back that runs but could use a little help. the mains and rods are tight but the rings are worn. i can't get into an expensive overhaul right now and plan to go with new rings. hone the cylinders and would like to lap the valves if that is possible. i did a search but didn't find much on valve work.
1. i assume those two piece guides go out the bottom toward the tappet chamber, is that correct?
2.i am thinking of buying the tool that the vendors sell, but am unsure how it works. do you put it around the valve stem and tap down on the valve to remove the guides?
3.if i go through this process to clean the valves , are they going to be centered in the seat? on modern engines you install the guide then grind the seat so everything is centered.
4. is there a better way to improve the seats without removing the guides? i might be able to hand lap the valves a bit without removing the guides, but seems like real tedious work.

[George Miller]

You will have to take the guides out. The valves have a mushroom stem. So you can not take them out with out removing the guides. That is if you have original two pice guides. If you do take the guides out it is a good idea to keep them in the same pair they were when you took them out. I also like to put them back in the same hole. It might not matter but why take a chance.

[Chuck Sea/Tac]

1) yes
2) yes

[RonC]

If you can, Buy new pistons, pins and rings and have the cylinders honed and pistons and rings installed. Replace all the valves with new stainless valves and have the seats ground and valves installed. I would also replace the tappets with the newer self locking tappets

[Dick Steinkamp]

You don't have to remove the valve guides to lap in the valves (in fact, you shouldn't in order to keep the valve centered). Using a valve spring compressor, compress the springs enough to remove the keepers. The valve will not be held down by the spring now and you can move it up and down and rotate it easily.

If you want to remove the valves to clean up the valves, springs, etc. of dried oil and carbon, You will need to remove the guides, but re-insert the valves and guides to lap in the valves.

A machine shop (or club buddy with the proper tools) is needed to properly grind the valve seats in the block and the valve faces if they need more than just lapping.

[Keith True]

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First,see if you really need to take them out and fiddle with them.Where you are just doing a get it by for a while thing,the valves might be fine.Dribble a little gas around the heads of each valve when they are closed.If it rushes right down into the port you may need to lap them.If nothing runs down,or slowly seeps down just leave them alone.If you do need to lap them just take off the springs and lap them in place.You really need an overhaul but there are thousands of A's running around that have been patched like you want to.

[H. L. Chauvin]

Hi Larry,

A. Just a humble suggestion only from hands-on experiences .... as opposed to a suggestion from after reading 20 years of past Forum comments:

B. Your wanting to do a partial re-build sounds like what we did 50 years ago after our being advised as youngsters only by vintage, professional mechanics who are all gone today. They were all mechanical miracle workers.

1. Sounds like a typical Model A engine that was operated extensively with no air filter and wore the cylinders & rings with road dust particles collected in the air; however, good Babbitt sounds like former owner(s) changed oil regularly ...... so Model A "typical" from years gone by.

2. Cylinders are now of larger diameter at tops where less lubrication was provided. (No doubt former owner(s) did not use top cylinder lubricant in gas like MMO that we were always advised to use from true mechanics who worked on these non-air-filtered vintage engines.) Cylinders are now smaller diameter at bottoms where cylinders were well coated with oil; hence, cylinders are now tapered partially because of lack of lubrication at tops of cylinders. (Oil is not only a lubricant ..... it also reduces temperatures).

3. Also, at present, with oil burning and carbon build-up in piston grooves, piston grooves now have carbon crud causing rings to stick & stay compressed after they descend; and piston rings cannot expand rapidly as they rise .... thus not sealing cylinder walls at tops of cylinders. Cleaning all piston grooves in existing pistons will greatly assist new rings to expand and contract and seal tops of worn tapered cylinders.

4. Many hone cylinders with honing stones attached to an electric drill ..... we were taught to use a slow turning hand drill, sliding up & down slowly with kerosene or cutting oil so as not to further increase the diameter of the cylinders ...... works great to roughen cylinder walls and seat rings.

5. Remove valves spring keepers, valve springs, valve guides, and valves and place all parts in separate areas numbered from one to eight after cleaning same, to insure reinstalling same in same locations.

6. Verify each valve seat fit by light grinding with tool similar to Bratton's #9210 and #9220 valve grinding compound. If valve fit appears OK at seats, check valve clearance ...0.011" intake & 0.0013" exhaust. Grind valves with valve guides installed.

7. Cut top of cylinder ridge with ridge cutter.

8. Clean engine after each individual mechanical procedure.

Hope this helps just to get started in the right direction and avoid future unwanted problems after engine start-up.