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Title says it. What's the minimum vs maximum? Thanks!
Wrist pin/rod clearance...floating 340 rods.
- Thread starter Cranky
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RustyRatRod
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Dang if I can find anything on it. I would say something like .0005 - .002. It won't be much.
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I couldn't find anything on the net either and I can't find my 'cheat sheet' pad (been too long since building anything) but a buddy of mine just commented that it should be .0006 to .0012. I have .0005 on a few with .001 on a couple....
Supershafts
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I'd stay with the .005 for the min side
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That much eh??
Supershafts
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The crank side should have .007 to start and up to .020 or slightly more so i'd like .005 up top, not exactly sure if the growth issue is that much of a concern as just a little more room to move side to side after hot
Meep-Meep
дворянин
Hell no .005". I bet it's more like .0005" to .001".
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OK, here you go. Right out of the 1968 factory book. .0000" - .0005". I have never seen a spec calling out zero until now. It also says in parentheses "light thumb push @ 70 deg F.
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OK, here you go. Right out of the 1968 factory book. .0000" - .0005". I have never seen a spec calling out zero until now. It also says in parentheses "light thumb push @ 70 deg F.
Supershafts
Well-Known Member
Wait i might be missing what he wants here are you looking for the wrist pin clearance or the rod to piston side clearance ?
If you're looking for the wrist pin clearance than yes it is .0010 or .0015
I had missed what he was looking for since he had rod and wrist pin rather than just wrist pin clearance...
That was why i mentioned the rod side clearance at the big end.
If you're looking for the wrist pin clearance than yes it is .0010 or .0015
I had missed what he was looking for since he had rod and wrist pin rather than just wrist pin clearance...
That was why i mentioned the rod side clearance at the big end.
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Wrist pin 'to' rod clearance. Where I live writing 'wrist pin/rod clearance means how much does the rod fit need to be over the pin. Even tho .0015 would probably work, I would think it's on the loose side.
Meep, never seen .0000 before either and that would definitely not be a light thumb push unless the rod was over 200 degrees and even then, it might not be a light push! At .0005, you have to hold your mouth to the left to get the pin to go in and with a light oil (10wt), it feels 'gritty' unless you rotate it pretty fast. The ones that are .001 feel pretty good. With .030wt, there is more 'grab' but once the oil film breaks loose, they feel better when the pin is turned but I think they will be fine. I'm about to take the mess to get it balanced so I'll talk to the machinist when I go. Sometimes we have pretty good conversations since I'm a machinist too but just not with engine machine work but I worked with close tolerances on other types of equipment and it's been many years since building an engine using floating rods so there's some cob webs going on in my cranium but I have two more engines in the works right after this one is done. Tanks everyone!
Meep, never seen .0000 before either and that would definitely not be a light thumb push unless the rod was over 200 degrees and even then, it might not be a light push! At .0005, you have to hold your mouth to the left to get the pin to go in and with a light oil (10wt), it feels 'gritty' unless you rotate it pretty fast. The ones that are .001 feel pretty good. With .030wt, there is more 'grab' but once the oil film breaks loose, they feel better when the pin is turned but I think they will be fine. I'm about to take the mess to get it balanced so I'll talk to the machinist when I go. Sometimes we have pretty good conversations since I'm a machinist too but just not with engine machine work but I worked with close tolerances on other types of equipment and it's been many years since building an engine using floating rods so there's some cob webs going on in my cranium but I have two more engines in the works right after this one is done. Tanks everyone!
RustyRatRod
Well-Known Member
Wrist pin always means wrist pin where I come from. Yeah, I knew it wouldn't be much at all. Guess it's a good thing you didn't run out and set it up at .005". (rolls eyes)
67 B-body
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Hmm,,,
Meep-Meep
дворянин
They did spec a light thumb push at 70 deg F. If you have both parts really, really clean - and I mean clean - you can do a light push at almost nothing. I'm putting together a 390 for my truck and the pin almost gets stuck trying to slide it through the piston and rod but a delicate touch and she goes right in and floats nicely. The Ford book specs around .0007".
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Rod side clearance will be on the order of .020".
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Rod side clearance will be on the order of .020".
RustyRatRod
Well-Known Member
That makes sense....even "zero" makes sense, because as it heats up, the pin enlarges, but so does the little end of the rod.
Supershafts
Well-Known Member
Well again i read wrist pin / rod clearance, so when checking wrist pin clearance the word rod never shows up, when checking rod clearance it is always at the main, we never use wrist and rod together, so when i had mistakenly read what i never ever used around here wrist / rod , and yes wrist pin is wrist pin, and you did not write wrist pin clearance you added to it and had a /
After meep used light thumb push i knew it was only the wrist pin, then i corrected it.
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