A question for the machinist in the group

[KenHaverhill]

I need some advice , I am installing new valves in a 1920 Fordson tractor. The valves have larger diameter stems and are all that is currently available
which is ok my guides are a little worn anyways. the new valves measure 11/32 .344 in diameter and I am not sure what size ream to buy , I dont want them to be to tight when hot ? Thanks in advance

[Scott_Conger]

For starters, measure the stems with a calibrated micrometer (not a dial caliper) and see if they don't actually measure .342.

[George Andreasen]

Be aware that the reamer requires a guide that fits in the valve head hole. Otherwise, the reamer can get tilted during the operation. Any machinist should be able to make one for you from mild steel, so that it's a "light" fit in the portion of the hole that is straight. After installing the guide, you simply run the reamer through the hole in its center, insuring a straight path. Go easy, never backwards and blow chips out as the reamer goes down.

[KenHaverhill]

The valve stems measure .344 ,my concern is how much clearance is needed for correct operation which would give me the correct size ream to buy,thanks again

[Scott_Conger]

This is what George is talking about. Just did a quick refresh on a pretty good engine that came with a blown up Mag. Engine ran very well with no oil burning except for a "puff" of smoke when it was first started. Decided to renew worn guides while I was at it. This is my setup...Use of the piloted reamer by hand requires diligent attention to keep it cutting with each revolution. This will cut a true-sized hole. If you just fart around and talk to your pal while lightly spinning this reamer, you will end up with results that you will not be happy with.

[Scott_Conger]

Ken

These sorts of reamers come specifically for either bronze or similar material, or for Cast Iron. You want Cast Iron. To make a true hole .002 larger than your stem, this is what you want...call them, give them the true diameter of your valve and application, and I am sure that this is what they will suggest: https://www.cylinderheadsupply.com/kl1136.html.

I get valves from Lang's and the ones they sell are .002 U/S and take a fractional reamer if I recall correctly. It's -5 out and too cold to go to the shop to check, so memory will have to serve.

[Scott_Conger]

Now, in fairness to full disclosure, it is highly unlikely that you will end up with valves that are still entirely centered on their seats. I always take my new valves to my favorite engine shop to have the seat face "kissed" to ensure no travel/handling damage remains, and then always end up cutting new seats that are centralized on the newly reamed guides. I use NeWay cutters and they are fantastic. I bought them when I had to do a cobble job for a friend in his driveway. Someone had reamed the guides free-hand and the valves came up at all sorts or crazy angles. Not a single one seated and all exhaust valves were terribly burned as a result. This was on a T with a "new engine". It was a very hard-to-start car from the get-go, and after about 4K miles was simply done for. Recutting the seats to line up with the crazy valves reinvigorated the car for many more miles. While it was gratifying to hear that car finally run right, the best thing was I ended up with great tools that have paid for themselves many times over.

[KenHaverhill]

Thanks for the help

[HaroldRJr]

I am set up pretty well for "valve jobs" in that I cut modern 3-angle valve seats with a very nice Neway carbide valve seat cutter outfit, and I very accurately reface valves with a very old fashioned (but very accurate) manually operated valve refacing fixture that also has a carbide cutter. In fact, I firmly believe that I can do as accurate a valve job as any auto parts store back-room machine shop, it's just that I probably take much longer to do a valve job. But that's okay, being long-since retired,....I've got time, right? I can say that I've done several valve jobs with this equipment and they've all turned out very well.

However, I've never reamed or knurled valve guides and I'd like to add to my "valve job" equipment (and skills) with whatever it takes to accurately deal with valve guides that are somewhat worn, but not to the degree that they need replacing. So, I'm very interested in George and Scotts posts above in this thread that addresses accurate reaming of valve guides. Accordingly, I have a question for either George or Scott, or whoever else might chime in on this:

George Andreasen mentioned that the valve guide reamer needs "a guide that fits in the valve hole", or, I guess I'd say "port".

Conjecture here for sure, as I mentioned that I have no experience reaming valve guides. However, I would think that having the reamer "guide" index off of the existing valve seat rather than the "hole" or the port itself, for a couple reasons:

First, the valve guides, altho' worn, originally did (and still do) remain concentric with (or, in line with) the existing valve seat. And second, the "hole" or port, is just a cast opening,...with just rough cast surfaces rather than a machined surface.

Again, never done this, but I really think there is a good chance that guiding the reamer with the guide positioned in a way that is not necessarily concentric with the existing valve seat might necessitate having to totally re-cut a new valve seat, which could conceivably entail removing a lot more material from the engine block,....really not a good thing in my opinion.

So,....does this make sense, or am I "overthinking" the issue,...??? I seem to be able to "touch-up" existing valve seats quite successfully with the 3-angle, narrow valve seat method, with the Neway expandable pilot WITHOUT a guide to stabilize the top end of the pilot, but I agree with George & Scott that it sure seems that reaming guides should not merely be done "freehand" but that the top end of the reamer should be "guided" and stabilized for accuracy,.....harold

P.S. Sorry to be so long-winded, but I always have a hard time explaining what I'm trying to say!

[Gene]

My dad was a MM mechanic and he ground 2 angled on a valve head, and where the two angles came together was what seated in the block. He also had a system where the valve rotated a little ever time the valve lifted. I was to little to know much about what was going on. Can anyone make a comment on this. He use to say I never had a valve job come back on me.

[NHUSA]

Ken,
I got a replacement motor for my 19 from Bill Thompson.
He should be able to help.
He lives in Sudbury and I believe he works at Clematis Machine shop in Waltham.
He last logged onto the old site on Dec 31 -
If you do a search on his name, town, and MTFCA you may be able to send him an email.