Tappet bores - New are .6235"

[Bryan]

I took all of the tappets out of my new block, have cleaned them up and inspected. All of them are measuring exactly .6235 at all points on the sides.   About 6 have minor wear rings perpendicular to vertical.  Since they move up and down I suspect these are from me turning the lifters around while taking the valves out.  Don't have a bore gauge to measure the bores, but only about 2 bores have any perceptible wobble when I try to move the tappet back and forth (side to side).  If it gets warm maybe I'll try a dial indicator while wobbling the tappet.  The bores look smooth.   Question, if I go my regular perfectionist route and buy oversized tappets, how common or how likely is it for a machine shop to rebore the tappet holes?  Is this common?  

[Sniper]

I dug into my 57 FSM which shows how to check and what the clearances are.  My earlier stuff didn't say, which is why I seriously dislike the multi-year consolidation manuals.  I attached the info here.

 

 

[martybose]

Just out of curiosity, are oversize lifters even available now?

[Bryan]

2 hours ago, martybose said:

Just out of curiosity, are oversize lifters even available now?

They are as far as I know. VPW.

[Matt Wilson]

I'm going to try to go through my saga (which is ongoing) and see if that offers any direction for you.

 

Here goes.....

 

I had a 230 engine in my '49 Power Wagon.  I rebuilt the 230 about 19 years ago.  Tried to do everything as correctly as I possibly could, being very picky,referring to the manual for everything (actually three different manuals I had at the time and occasionally a fourth), getting stuff redone when it was not done correctly the first time, etc.  That is, except for one area - the tappets and their bores.  I measured the clearances the way Sniper's manual excerpt describes.  In fact, I have a manual that shows the same procedure, except that its stated wear limit is 0.0015" clearance instead of 0.002" (the stated new part clearance is 0.0000 - 0.001", which is smaller than I expected, honestly, and obviously, you don't actually want zero clearance, but I guess they had to give a range).  That manual is Army manual TM 9-1840A/TO 19-75B-15, which is for the Dodge M-37 (military truck, in case you're not familiar).  It uses the same engine as my Power Wagon, with minor differences, and same engine as most any other light truck or passenger car.  When I measured the clearances, they all came back significantly beyond the wear limit, with some being 3 - 4 times that.  Being somewhat inexperienced, I didn't know what to do about this, and I was probably exhausted from the whole process of the rebuild, as there were many issues along the way (another story).  I think I knew that oversize tappets were available (because that manual talks about this), but I seem to recall talking to several machine shops and they didn't have the tooling to oversize the bores, and I do recall very clearly that they all said this amount of clearance would be fine, saying this clearance is not that critical.  So having gotten expert input, I went ahead with the situation as I just described.  I reassembled the engine, installed it, and it ran well for several thousand miles (probably in the neighborhood of 8,000 miles, but it's hard to say for sure because the odometer didn't work - but it was my daily driver for over a year and I knew how many miles all my routes were, and my routine was pretty consistent). 

 

One day, I took the valve/tappet covers off to look in there and noticed four or five of the tappets had streams of oil full of metallic shavings flowing from the bores.  Beautiful, glitter-filled oil, but very alarming.   My mind immediately thought of the large clearances, but to this day, I don't really know if that's what caused the metal shavings or not.  I also remembered an early valve adjustment session when I noticed that a few of the tappets weren't rotating, or at least not consistently like most of them.  So I wondered if that could have contributed to the glittery oil.  Mostly, I blamed the excessive clearances, but in any case, I couldn't continue to run the engine like that, so I pulled it with the intention of repairing it, but it sat mounted on my stand for several years while I licked my wounds and focused on other things happening in life and tried to get motivated again.

 

Fast-forward several years and I finally had time and took interest in the truck again and decided I would install a 25" engine, then made up my mind it would be a 265.  As I was planning that build, I swore that I would do whatever was needed to achieve proper tappet-to-bore clearances (along with everything else being correct).  When I performed the clearance checks, most or all of them were beyond the 0.0015" wear limit stated in the manual I mentioned above.  Several had 2 - 3 times the allowed wear limit clearance.  I bought 0.008" oversize tappets, which are available from several sources, and took them and the block to a machinist to rework the bores so they would have 0.001" or slightly less clearance with the tappets.  When I got them back, I found the clearances were now beyond wear limits compared to the 0.008" oversized tappets.  The machinist had screwed up.  Perhaps I should have taken everything back to the machinist and demand he make it right, but based on comments he made relating to other work I had done at the time, I had no confidence he would be willing to do that.  Also, if he screwed this up this time, why should I expect him to get things right the next time.  Instead, I began figuring out my next move. 

 

I considered having the tappets plated to take up the excess clearance, but there were issues with that approach.  I also considered opening the bores to accommodate press-fit bushings that would then be honed to fit the oversized tappets, but that's when I found some 0.030" oversize tappets.  I spoke to several machine shops and they all expressed a lack of interest or equipment for doing the job (a lot of them seem to think they need a specialized CNC setup with custom fixturing, like they use for their high-end racing V8 tappet bore work, but I'm not convinced that's what's needed if you can find someone who's willing to just take the time to set up their mill for this job).  However, one shop gave me some guidance and some encouragement to do it myself (of course, it begs the question....why wouldn't he do it, if he's so confident I could do it?).  Anyway, armed with that, I set out to gather the tooling I need to do the job myself.  With the guidance I received from the machinist and from a local tooling shop, I bought a standard chucking reamer to open up the bores part-way and a custom piloted reamer to open them the remaining amount so that I would get right at 0.001" clearance.  I have those tools now and will hopefully get to that job in the next several weeks.  I'm nervous, because I'm not really set up to do that kind of work, but the machinist and the tool company thought I could do it.  I do have my old 230 block that I plan to practice on first, so that should give me some foreknowledge of how it will go on my "real" engine (the 265).  In the end, I may chicken out and try again to find a shop to do it for me using my reamers.

 

So what is all of this telling you?  You can take what you can glean from it, but I think one thing it says is that it might be easier said than done to find someone who is willing and is competent to do this kind of work.  Some shops will advertise that they do this type of work, but when you talk to them, they'll say they can't do our engines because they only have fixturing for a limited range of engines.  Honestly, I don't think special fixturing is required.  If you lay the block upside-down on a milling machine and perhaps shim it as necessary to align the milling head with the tappet bores (you can't assume that the bores are exactly perpendicular to the block deck due to normal factory machining errors), I think you (your machinist) should be able to do this job.  If the bores are not very far off, the mill could be used to make them perpendicular to the deck, although actually, the preference is probably to make them perpendicular to the camshaft bearing bores if that's possible.  In any case, I doubt the bore alignment is off by enough to matter for most of us.  The point of all this is that I think a machinist who cares and has a large enough milling machine can do a perfectly good job of oversizing the bores.

 

i think my story also says that if your clearances are only slightly out of sorts (say right at the wear limit or a few ten-thousandths beyond), then maybe it's worth keeping things as they are, or perhaps finding some of the 0.001" oversize tappets that some manuals talk about.  Those might be just enough to bring clearances right back where they should be, although be aware that your bores are no longer perfectly circular, so oversized tappets might be a little tight in the fore-and-aft direction, since that's the direction of least bore wear.

 

A point for measuring bores is to consider using plug gages.  I tried endlessly to use telescoping (snap) gages and outside micrometers, and I think I got fairly accurate answers, but when double-checking my measurements, I would occasionally get a number way out in left field.  Those gages are tough to use.  There are probably other measurement tools I could have bought, but even those sounded difficult to use.  I finally discovered plug gages at McMaster-Carr, which come in 0.0005" increments.  Those are best used for holes that are close to circular, like mine, and the more out of round they are, the larger the error.  I bring it up only as a consideration.

 

Another point is that I rarely hear anyone else talk about having issues with this area of the engine, and it seems that people frequently ignore these clearances during rebuilds, so unless you have truly excessive clearances, or damage to the bores or tappets, it may not be a big concern.  A couple of my manuals even mention that tappets rarely need replacement since they are constantly bathed or sprayed with oil.

 

Another piece of info...different repair manuals call out different clearance specs, so that adds to the confusion over what's acceptable.  The M-37 manual I mentioned above calls for a new-part clearance of 0.0000 - 0.001 and a wear limit of 0.0015.  Another manual (TM 9-808, which is a WWII Dodge 3/4-ton truck manual) calls for new-part clearance of 0.0000 - 0.0007 (yes, seven ten-thousandths), and a wear limit of 0.0025 in terms of tappet stem diameter wear, with no mention of bore wear.  Another manual, D-12154, which covers Chrysler Six Cylinder Industrial Engines, calls for a new-part clearance of 0.0000 - 0.001 and wear limit clearance of 0.0015, like the first manual I mentioned.  Then there is Sniper's manual that seems to indicate a wear limit of 0.002".

 

Finally, you asked in a separate post about whether the tappets have a crown where they contact the cam.  To my knowledge, all of the Chrysler/Dodge/Plymouth/DeSoto flathead six tappets do have a crown.  It's not obvious to the naked eye, but if you hold a tappet up to a straight edge, or better yet, if you hold two of them with their cam contact faces against each other, you'll see that those faces do not sit flat on each other.  If you re-use your existing tappets, you should get them resurfaced by a cam grinder.  Many of them (probably most or all of them) offer this service.

 

Hopefully this is of some help, even though it may be hard to decide what the takeways are.  Let me know if you have questions.

Edited January 30, 2022 by Matt Wilson

[Bryan]

Wow!   That's what I was worried about, a machine shop messing it up.  I'll check the clearances using the method Sniper presented and will see what I got.   I did measure the tappet mushroom end with a straightedge, and they are crowned.  Might get a couple of tappets, one standard and if possible a .001 oversize to see how they fit.  I have tappets that look in good shape, but a few have rings around them that you can feel with a fingernail (barely).  Thanks again for the input.   Bryan

[Matt Wilson]

No problem.  Hopefully there is some insight somewhere in there.  As for the rings around those few tappets of yours, I don't know if I would worry about that.  I think the barrel section of the tappet can tolerate some damage here and there, as long as it's relatively small in area compared to the overall size of the barrel, and as long as there is no raised material to cause damage to the bore.  The condition of the bottom end where it contacts the cam lobe, and the diameter of the barrel (since that affects clearance within the bore) are the most critical things.  Also, the condition of the adjuster screw, where it contacts the valve tip is important, meaning you don't want it be dished out from wear.  I would get the tappet cam contact surface re-worked and have the adjuster tip refaced too.

 

I'm sure there are shops out there who CAN and WILL do a good job on tappet bores, without needing special equipment.  I've read about them, but they are apparently hard to find, even in the large metroplex of Dallas-Fort Worth, where I live.  I think I could probably convince the one machinist who gave me encouragement to do the reaming myself to do it if I tried a little harder.  I think he is just busy and it's a little bit of an unusual type of job for him, so he was hesitant.  I may try to go to him again and see if he'll do it, but we'll see...

 

I've never tried to buy the 0.001 oversized tappets, but I suppose they are out there.  I found the 0.030" oversize tappets to be hard to find, but I found them at AMS Obsolete in Georgia.  They were pricey, but I was grateful to find them.  You might give them a try for the 0.001 parts.  You could also try Vintage Power Wagons, Andy Bernbaum, Midwest Military in MN (John Bizal).

 

One thing I should note that is that when I've bought replacement tappets, especially the oversize ones, several of them have had rust on them.  In some cases, it was enough that they were unusable and unrepairable, so I called the supplier to get replacements, but they instead credited me for those, saying the rest of their stock were probably not any better.  They were obviously not going to take the time to inspect them closely enough to find the ones that had no rust.  Replacements I found elsewhere sometimes had some rust as well, even though I specifically asked for ones without rust.  Some of the 0.030 oversized parts have some rust.  If the rust is minimal in area and is confined to the barrel section, then I give it a little localized polishing and I don't worry about it any further, but if there's any at all on the cam contact surface, as is the case in several of the 0.030 oversize parts, then I won't use it as is.  If it looks like it's just very, very shallow surface rust, then I might try giving it a slight polish (just a few swipes with some 320-grit paper as suggested by one long-time cam grinder).  If the cam contact surface has anything deeper than that, then I consider it no good and I will send those tappets off for resurfacing.  I could try to ask the supplier to replace them, but I have no confidence that what I would get would be any better, as it would require the supplier to remove ALL the cosmoline and examine each tappet VERY closely under some level of magnification to be sure there is absolutely NO rust.  That's very tedious and if they miss even a small spot, I'll still have to do something about it, so it's just not worth it to them to take that kind of time.  It's not ideal, but I don't think I can fault them for that.  I just have to be ready to send those tappets off for refacing and I figure it's a part of dealing with the situation.  Others may see it differently, but in my view, most suppliers are simply not going to take that kind of time, especially if there's a good chance they'll miss something anyway.

 

I just started following your engine disassembly thread last night and I'll keep an eye on it periodically.  I'll be interested to see how your tappet situation pans out.

 

Good luck!

Edited January 30, 2022 by Matt Wilson

[Bryan]

Measured the tappets in bores today besides other stuff.   5-1 measured .001. The rest ( 5-2, 6-1, 6-2 and 1-1 ) measured less than .002. More like .00175 to .002.   Heck, I might buy a standard size new tappet and see what it measures. All the old ones were .6235 consistently.  Was hard to use the dial indicator, was trying to keep it clean.  You have to get it perpendicular in 2 directions, and the point sweeps sideways at an angle when you adjust it. Plus getting it at zero so it just a little pressure barely moves the needle.

[Bryan]

Tappet question.  Does anybody have some new standard tappets that they could measure with a digital caliper exactly and see what diameter they are?  My present ones are .6235

[Matt Wilson]

The tappets I put in my 230 were probably new (NOS) at the time, and I think I can put my hands (and micrometer) on them when I get back in town at the end of this week.  I'll try to remember to do that.  I expect they will be somewhere in the range of 0.6235 - 0.6240, as that's what the manuals all state they should be for new parts. 

 

I can tell you by memory that all the unused oversize tappets I've measured (several dozen of them) were right in the range where they were supposed to be for new parts, and I seem to recall that most of them were at or very near the bottom of that range.  So your measurements for your tappets (0.6235) sound just right for standard size tappets, although at the very bottom of the range.  It sounds like they have very little wear.

[James_Douglas]

I will be doing a new engine later in the year. I plan on having all the tappet bores sleeved with one of the many bronze blends available for such use. One can then use a tighter clearance due to the silicon in the bronze. I can then use also new standard size tappets.

 

James

[Bryan]

5 hours ago, James_Douglas said:

I will be doing a new engine later in the year. I plan on having all the tappet bores sleeved with one of the many bronze blends available for such use. One can then use a tighter clearance due to the silicon in the bronze. I can then use also new standard size tappets.

 

James

Are you going to cut the tops off of them and blend them into the ports?

[James_Douglas]

I am not sure I understand the question. One overbores the tappet bore holes and then presses in the silicone bronze sleeves then hones or reams them to the stock hole size. You then slip in the tappets in the normal manner.

 

I think you are talking about bronze valve guides. I am talking about tappet bores. For valve guides, I am going to have bronze one machined in place of the cast iron ones. I am looking into some kind of seal on the intake guides as well.

 

James

[Bryan]

36 minutes ago, James_Douglas said:

I am not sure I understand the question. One overbores the tappet bore holes and then presses in the silicone bronze sleeves then hones or reams them to the stock hole size. You then slip in the tappets in the normal manner.

 

I think you are talking about bronze valve guides. I am talking about tappet bores. For valve guides, I am going to have bronze one machined in place of the cast iron ones. I am looking into some kind of seal on the intake guides as well.

 

James

You're right. Had something else on my mind and got into a rush.

[Bryan]

I ordered 2 standard tappets with screw heads from Vic's Dodge garage (trucks).  Good thing about their site is they only charged about $3.60 for shipping. Another well known site I looked at had $15 shipping.  I'll measure them.

[Bryan]

Got the 2 tappets from Vic's Dodge garage. Both bearing surfaces measured exactly .6235 like the ones I have.  Reckon I'll keep the existing ones and just replace a few with rough surfaces, send them off to have the tops and bottoms refinished.

[Bryan]

Bottoms have a crown in the middle which I think is normal.

[MarcDeSoto]

All this talk about tappets makes me wish the radio show Click and Clack, the Tappet Bros. was still on!  Funny, when I rebuilt my engine, I had no problem at all with the tappets.  I think they were machined and then I put the original tappets back in.  

[Bryan]

2 minutes ago, MarcDeSoto said:

All this talk about tappets makes me wish the radio show Click and Clack, the Tappet Bros. was still on!  

They stopped a few years back, think was on Saturday mornings.  Funny and informative.

[MarcDeSoto]

You can still hear them streaming on the Net.  I read that they were on for 37 years!  I was surprised to learn that they were in CARS and CARS 3.  The older brother Tom died in 2014.  Ray with the black moustache is still around born in 1949.   It was not a serious auto show, probably 75% jokes and 25% shop talk.  They probably would not have made it to a national audience if it was serious show.  I saw that they wrote some books also.  One is Maternal Combustion!