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Lifter/Tappet-to-Bore Clearance


Matt Wilson

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Hi guys,

 

I'm rebuilding a 265 to go into my '49 Power Wagon, and I checked the clearances between the tappets and their bores.  One manual says to use a dial indicator, and says the indicator reading is the actual clearance, so I did that, exactly as shown in the figure provided in the manual.  Most of the readings are 0.0025 - 0.003", with a couple of them being 0.0035", a couple being 0.0015 or 0.002" and one being 0.004".  Two manuals say the clearance should be 0.000 - 0.001" and another says it should be 0.000 - 0.0007".  Obviously, my readings are far beyond that, but I also have a hard time believing the clearance should be as small as the manuals say.  That just seems like asking for trouble to have such a tight fit.  Looking online to find clearance specs for lifters in other engines, it seems that most of them call for a minimum of 0.001" and as much as 0.0025" or some even say 0.003" is ok.  Of course, these are for engines like Chevy and Ford V8's, but at least they are for lifters with flat bottoms (not roller lifters).  Even so, most of my readings are at or beyond those upper limits.

 

I also measured the tappet diameters and found them all to be less than minimum for new parts (not too surprising, I suppose), and several are approaching the wear limit.  The new part dimensions are 0.6235 - 0.6240" and the wear limit is 0.6225".  Several of mine were in the 0.6227 - 0.6232" range.

 

I have a set of NOS 0.008" oversize tappets that I could take to a machine shop and have them bore out the holes, but sometimes doing something to fix a problem can cause more trouble.  Do I really need to worry about the clearances I'm seeing?  I'm a little leery of leaving them as is, because I had a 230 flathead with similar clearances and 3 or 4 of the tappets/bores eventually produced oily trails full of metal shavings.  I don't know if that's because of the looseness of the tappets in their bores or something else.  I seem to remember that some tappets didn't rotate like they should.  I suppose they could have been the same ones producing metal shavings, but I don't know for sure.

 

I'd like to hear your input.  If I do use the oversize lifters, what clearance do you recommend?

 

Thanks,

 

Matt

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Hey Matt

There's a few things coming into play here...especially with a 70+ year old engine.

Lifter to bore clearance:

It MUST be measured with a dial bore guage. Then that reading compared to the prospective lifter. In this method you will be able to determine the taper of the lifter bore as well.

A clearance of .001 to .0017 is adequate. Anything more and oil pressure can be affected.

Taper of the lifter bores can and will cause non rotation of the lifter, as well as an OS  lifter bore.

  If in doubt, and you should be with lifters worn to the min spec...replace them.

You will gain in 2 areas, one being a lifter that runs true, and you will regain the crown that's lost on your worn out ones.

 That being said, check your camshaft!!!

 If the taper on the lobe is gone, and I guarantee that it is....then putting new components against a junk cam will yield junk results....lifters that will fail....crowned lifters on a flat cam = destruction. 

  My advice in a nutshell...

Your spending good money to build this engine...build it right and it will repay you over and over...cut corners and you'll pay more in the long run.

 Ps. Make doubly sure you have adequate zddp in your oil, its essential since all new oils don't carry it. Heavy truck oils such as 15-40 used to be a good replacement,  not anymore. Theyve curtailed the use of it too.

Lucas, stp and several others make aftermarket additives...use them.

Good luck :^)

Edited by mechresto
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One small note ... there is no pressure fed oil to the lifters and tappet bores on the 23 and 25" engines. 

The lifters/bores are lubed by the connecting rod squirt holes.?

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Was your engine previously rebuilt ...undersize rods mains, bored out? An old high miles ect engine?

Ugly oil and filter?

I'm getting at why the lifter bore wear?

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21 hours ago, Dodgeb4ya said:

Was your engine previously rebuilt ...undersize rods mains, bored out? An old high miles ect engine?

Ugly oil and filter?

I'm getting at why the lifter bore wear?

No, actually, none of the above.  Well, I don't know the mileage on it, but the engine had never been rebored, and the crank journals were all standard size.  The engine wasn't particularly gunked up either.  It was definitely time for a rebuild, but I don't know why the lifters are as loose as they are. 

 

Now, my previous engine - the one with the trails of metal debris coming from the lifter bores - it had been rebuilt at least once before I rebuilt it, so it's more understandable on that one.

Edited by Matt Wilson
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I just worked on a 41 Buick 70 series....lifter spec of  .0025" max clearance.

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Thanks, that seems a lot more in line with what I would expect.  The Buick is not a flathead, right?  Not sure if that makes a difference or not, since the lifters in a flathead are closer to the exhaust region.  What's the diameter supposed to be on those Buick lifters?

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On 9/6/2018 at 8:39 PM, Matt Wilson said:

Thanks, that seems a lot more in line with what I would expect.  The Buick is not a flathead, right?  Not sure if that makes a difference or not, since the lifters in a flathead are closer to the exhaust region.  What's the diameter supposed to be on those Buick lifters?

The Buick lifter diameter is just under 1.00"

The engine is OHV... 

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  • 1 year later...

Hi All,

 

I'm resurrecting this topic.  Some months ago, I decided the clearances I was measuring were more than I was comfortable with, so I took my 0.008" oversize tappets and my block to a machinist to have the tappet bores machined oversize.  I provided the machinist with the manuals that specify the clearance for new parts (one manual says 0 - 0.0007" and the other says 0 - 0.001").  He performed the work and when I picked up the block from him, he said he had gotten all the clearances to around 0.0006 - 0.0008".  However, when I later measured the clearances using the method I previously described (dial indicator placed on the "head" of each tappet and rocking the tappet back and forth in its bore), I got numbers ranging from a little over one thousandth to about 0.0025".  This is significantly better than some of the previous clearances, but still far beyond the limits stated in the manuals.

 

I guess I'm to the point where I can either have the loosest bores sleeved to take up the clearance (some shops will do this) or I can just leave it as is.  A part of me thinks the clearances in this area of the engine must not be terribly important since I've NEVER seen anyone talk about them in any engine rebuild threads on this forum or any other flathead six forums that I visit.  I'm sure I'm not the only person who has an engine with excessive tappet bore clearances, but the fact that no one has ever traced any problems to these clearances makes me think they are not critical at all.  But then again, I can't help but to recall the metal shavings coming from my other flathead that had LARGE clearances, but as I mentioned before, there could have been other reasons for these metal particles.

 

So.....I'm revisiting this topic to see if anyone else has any additional input.  I know it may seem like I'm making a big deal of all this, but if this engine rebuild doesn't work out for any reason....I'm basically done with this truck.  My wife and my finances won't let me do any more projects of this level of expense again, so it's GOT to be right.

 

Thanks,

 

Matt

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I wouldn't worry about your clearance...I got .001" to.0015" on a good tight  running 413 six.

I checked in all bores.... high middle and low positions.

I could check another engine that's assembled if you like later...got to get it out to do that..

413 Flathead Lifter bore Clearance (10).JPG

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Well, I certainly appreciate the response!  I really don't want to put anyone out by asking to have more clearances measured, but if it's not much trouble, then go ahead;  Otherwise, please don't worry about it.

 

By the way, do you know what diameter those lifters are?  The larger the diameter, the greater the clearance can be (and should be).

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My lifters are .717"... my clearance is 1/2 of that reading. perfectly OK....     .00075"1421688431_TappetBoreClearance218230.625Bore(1).JPG.3b5f80d0791963259b8383234100869d.JPG

The 218,230 lifter bore is .625". The following info is out of a 1954 Dodge C1 shop manual....the V8 lifters are .904" and actually are a tighter clearance. I'm sure you are A-OK for clearance. The C1 book has the only lifter info i can find easily.

I will Measure some lifters in a 265 for you tomorrow.

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Yes!  That image from your shop manual is exactly like the one from my manual.  You mentioned that you checked your 413 with the lifters in the low, middle and high positions.  I suppose the 0.0015" reading was with lifter in the low position?  That's how it appears in the photo, and I think that's the position that really matters, per the image in the shop manual.  With the lifter any higher than that, the clearance will look larger, assuming the dial indicator is raised higher accordingly.

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Notice .003" IN and .005" EX are the limits...

Lifter readings didn't change but maybe .0003"... of no concern at all on these old engines.... new cars it's a big deal.

I've never dealt with these lifters being a issue and have  rebuilt at least 30 of these flat head sixes not including the flat head eights.

That's not including ones already rebuilt installs. Never an issue on lifters...if the lifter is too tight it won't spin then you have a serious issue of lifter face and cam wear.

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30 minutes ago, Dodgeb4ya said:

Notice .003" IN and .005" EX are the limits...

Lifter readings didn't change but maybe .0003"... of no concern at all on these old engines.... new cars it's a big deal.

I've never dealt with these lifters being a issue and have  rebuilt at least 30 of these flat head sixes not including the flat head eights.

That's not including ones already rebuilt installs. Never an issue on lifters...if the lifter is too tight it won't spin then you have a serious issue of lifter face and cam wear.

Wow, 0.003 and 0.005 are lifter-to-bore clearance limits?  Three of my manuals say the wear limit on this clearance is 0.0015".  I wonder if you might be looking at the valve stem-to-valve guide clearance?  Those numbers (0.003 for inyaoe and 0.005 for exhaust) match what my manuals state for that type of clearance.

 

With so many engines under your belt, and so many other people who have worked with them, and not a single person, as far as I can tell, has ever mentioned this to be a problem, I'm leaning toward letting it go.

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Here are the 265 Readings.0018". = .0009" actual clearance. IMO .002 to .0025" would be just fine...... actual clearance.

The lifters are to be checked washed and  dry ...I pushed and pulled as hard as I could...This is a good running engine 89,000 miles.

As for the spec chart...I posted...here is the rest of the pages if you can read it that refer to that lifter bore chart...I didn't state it wrong maybe the book did.

The shop manual specifies the "Lifter" max wear clearances in that chart...it's the same #'s for valve stem clearances too. Wrong or right just the info out of the factory book.

I'd get on with it and put the engine together before you possibly get booted by the wife?

265 Lifter Side Clearance Total Divide it by half for actual reading .0019 No. 12 Ex (1).JPG

265 Lifter Side Clearance Total Divide it by half for actual reading .0018 No. 12 Ex (2).JPG

IMG_1853 de.JPG

IMG_1953.JPG

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Well, that's interesting indeed.  Your manual says the dial indicator reading is to be divided by 2 to achieve the clearance.  My manual shows the same figure, but says the dial indicator reading is the direct measurement of the clearance and says nothing about dividing by 2 or otherwise modifying the number to get the clearance.  Interestingly, there is a section of one or more of my manuals, where it talks about using a dial indicator to measure the clearance between the valves and their guides, and it involves multiplying the dial indicator reading by 0.5 for the intake valve and by 0.44 for the exhaust valve.  This is with the dial indicator against the valve head and the valve head sticking up above the block a certain amount, where the motion would be exaggerated, so the true clearance is smaller, as indicated by the multiplication factor.  In light of this and the clearances listed in your manual, which look like valve stem clearances, rather that lifter bore clearances, I have to wonder if, when your manual was being written, someone erroneously copied the valve stem section into the lifter section.  Seems like too gross an error to be the case, but it does seem to look that way - either that or my manual is wrong.

 

In any case, your total reading of 0.0018" in a good-running engine is not terribly smaller than the largest of my readings, which is about 0.0025".  So again, it seems to point toward my clearances being ok

 

Thanks again!  I really do appreciate the help.

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Run with what you got...It will be good!?

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The interpolation of the tappet bore clearance by rocking the head back and forth seems like it would be prone to lots of variables, especially if one is supposed to plug the results into a formula to arrive at the supposed "real" clearance...

 

This reminds me of the manual's method for determining the piston to cylinder bore clearance as well. I didn't like the published method, so...

 

I measured both with various snap gauges and micrometers. This is probably how the shop that performed the machining discussed above measured it.

 

BUT....I agree with B4YA's assessment.... probably all good (nice Starrett, BTW...that's the real deal!).

 

Hey Matt, I was just thinking about you the other day...been meaning to check in. Did you get the crank back from Armando? Hopefully so, by now!!!

 

 

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16 hours ago, John-T-53 said:

The interpolation of the tappet bore clearance by rocking the head back and forth seems like it would be prone to lots of variables, especially if one is supposed to plug the results into a formula to arrive at the supposed "real" clearance...

 

This reminds me of the manual's method for determining the piston to cylinder bore clearance as well. I didn't like the published method, so...

 

I measured both with various snap gauges and micrometers. This is probably how the shop that performed the machining discussed above measured it.

 

BUT....I agree with B4YA's assessment.... probably all good (nice Starrett, BTW...that's the real deal!).

 

Hey Matt, I was just thinking about you the other day...been meaning to check in. Did you get the crank back from Armando? Hopefully so, by now!!!

 

 

Hey John! Thanks for the input.  Yes, I agree that the readings are probably not 100% accurate.  I have a set of snap gages (telescoping gages). Maybe I will try getting the clearances by using those, although I have found them to be somewhat subjective as well, requiring care and a sensitive touch to get a reasonably accurate reading.

 

As for Armando....funny you should ask, because I just got the crank back from him last night.  He had it for about 4-1/2 months (since mid-May).  I was beginning to get a little nervous about how long he was taking, but it's all good now.  I haven't double-checked his measurements, but I plan to.  Based on his reputation, I expect everything will be 100% spot-on.  The only thing he was not able to do was repair the damaged pilot bushing bore.  He says his lathe is not large enough to accommodate the 265 crankshaft, or he would have done that, and would have made a bushing for me.  I'll have to take it somewhere else to get that done.  Thanks for asking!

Edited by Matt Wilson
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6 hours ago, Matt Wilson said:

Hey John! Thanks for the input.  Yes, I agree that the readings are probably not 100% accurate.  I have a set of snap gages (telescoping gages). Maybe I will try getting the clearances by using those, although I have found them to be somewhat subjective as well, requiring care and a sensitive touch to get a reasonably accurate reading.

 

As for Armando....funny you should ask, because I just got the crank back from him last night.  He had it for about 4-1/2 months (since mid-May).  I was beginning to get a little nervous about how long he was taking, but it's all good now.  I haven't double-checked his measurements, but I plan to.  Based on his reputation, I expect everything will be 100% spot-on.  The only thing he was not able to do was repair the damaged pilot bushing bore.  He says his lathe is not large enough to accommodate the 265 crankshaft, or he would have done that, and would have made a bushing for me.  I'll have to take it somewhere else to get that done.  Thanks for asking!

 

Geezus..... I know he's always behind schedule, but not that far behind. Well, at least I warned you, but the finished product is all that matters now. He'll be grinding my 440 crank regardless, I don't care how long it takes. I think he took about three months when he did my last one for the 230 that I have in the truck now.

I'm looking forward to seeing some photos of the finished crank when you can get them posted here! Send me some photos of his shop too, if you don't mind....

 

 

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On ‎10‎/‎7‎/‎2019 at 5:37 PM, John-T-53 said:

 

Geezus..... I know he's always behind schedule, but not that far behind. Well, at least I warned you, but the finished product is all that matters now. He'll be grinding my 440 crank regardless, I don't care how long it takes. I think he took about three months when he did my last one for the 230 that I have in the truck now.

I'm looking forward to seeing some photos of the finished crank when you can get them posted here! Send me some photos of his shop too, if you don't mind....

 

 

Yeah, I was getting a little worried that this was going to turn into one of the 2-year deals that I read about on a couple of other forums.  I actually asked him about that before taking the crank to him, and he said he's only done that in instances when he knew the owner had a very long project and didn't need the crank back anytime soon.  Still, I was worried for a while, and am glad it didn't take as long as that.  Armando is known for taking a long time, but everyone said he's the best of the best, so that's what eventually won me over in deciding to use him for this work.  I made sure to call him just about every week, just to let him know I care.  He's always polite, a very nice guy and I treated him the same way.  He admits that he's not good at schedule matters.  I still have a little more stuff to do before I can reassemble the engine, so his timeline turned out not to be a big deal.  A couple more months and I think it would have been.

 

In any case, here is a photo of my crank in my garage this morning.  If you (or anyone) is interested in seeing an up-close pic of anything, let me know.  I guess I could take some close-ups of a couple of the journals, particularly the radii.

Crankshaft.png

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