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Binding wrist pin...
- Thread starter Morris
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I think what he means is have them honed to fit kinda like king pin reaming.
tomshobby
Yoda
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Yes. They are usually made with an interference fit so they can be made to match. The reason is that they need to be a very close fit. If they were made to an off the shelf dimension they would not account for any wear or the +/- would either be tight or loose. The pin doesn't have the ability to withstand the hammering of ignition like the rod bearings on the crank.
Also when they are fitted they will be aligned with the lower bearing. ie - no twist.
Also when they are fitted they will be aligned with the lower bearing. ie - no twist.
Spridget64SC
Jedi Trainee
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Morris:
If this was a straight rebuild with existing components, check for burrs on the wrist pin or the bushing. I run into this often on rebuilds and will clean up the wrist pin bushing with some 3M Scotchbrite pad or very fine (320+) body paper in the parts washer. Hold the wrist pin in the vise with some aluminum soft jaws, either fancy or homemade (bent sheet) and polish the wrist pin with some fine (320+) cloth strips. Use a shoe polishing motion and rotate the pin. Do this lightly and then clean well. With every thing clean and nice, the pin should slide nicely in the bushing and also in the piston. Check the piston pin bores for scores. You can do the same with the piston and some fine paper wrapped around your finger. Just a nice light polishing effort.
If you put in a new pin bushing in the rod, or maybe put in a new pin or piston combination, then it is best to go to a machine shop and have them hone the bushing to size. I go for a 0.0004-6" fit. Less than a thousandth. They'll need the pin to fit.
The bushing should not require reaming. That's too coarse an adjustment. Just honing.
If the 1500 uses circlips in the end of the piston pin bores to locate the wrist pin, then you might have picked up a few light scores on things when removing the pin. Clean up everything and hand fit on the bench to find.
HTH
Mike Miller
If this was a straight rebuild with existing components, check for burrs on the wrist pin or the bushing. I run into this often on rebuilds and will clean up the wrist pin bushing with some 3M Scotchbrite pad or very fine (320+) body paper in the parts washer. Hold the wrist pin in the vise with some aluminum soft jaws, either fancy or homemade (bent sheet) and polish the wrist pin with some fine (320+) cloth strips. Use a shoe polishing motion and rotate the pin. Do this lightly and then clean well. With every thing clean and nice, the pin should slide nicely in the bushing and also in the piston. Check the piston pin bores for scores. You can do the same with the piston and some fine paper wrapped around your finger. Just a nice light polishing effort.
If you put in a new pin bushing in the rod, or maybe put in a new pin or piston combination, then it is best to go to a machine shop and have them hone the bushing to size. I go for a 0.0004-6" fit. Less than a thousandth. They'll need the pin to fit.
The bushing should not require reaming. That's too coarse an adjustment. Just honing.
If the 1500 uses circlips in the end of the piston pin bores to locate the wrist pin, then you might have picked up a few light scores on things when removing the pin. Clean up everything and hand fit on the bench to find.
HTH
Mike Miller
Hap Waldrop
Yoda
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Yep, Morris you probably remember, the post I made a few years ago about Ray's connecting rods I did for him in the hot rod 1275 I built for him. I showed pictures of how the big ends of the rods were resizied on my Sunnen hone, well you do the same job on small ends with floating pin type pistons with smaller SL mandrels made for this job, your pin size is .812" on the 1500, same as the 1275 (of course the 1275 are a press fit stock pin unlike the 1500 which has floating pins), you'll need about .001 cleanrece for this union. I'd also during assembly use light smear of a good moly assembly lube, not that red crap they sell at Autozone, CRC makes a good one, you can get it at NAPA, comes in a black tube.
And one is correct to beleive, that with new bushings it would almost always require honing to fit.
Also worth mentioning you sometimes have to hone a piston for a pin fit as well, I order all my JE race piston without pin fit and do it myself, and sometime even on a stock off the shelf piston I don't like the fit between the pin and piston's pin bore hole and will hone them just a tad to get the fit I'm looking for, this would apply to either a press fit or flaoting pin application. Another thing to keep a eye on is lubricatin during assembly between the pin and the auminum of the piston, I use a special lubrication oil for this made by Goodsen Tool, it is specially made for this, it spray in thin like a regular lubricating oil, then thickens up to stay stuck on the parts untill inttial crank up is done. This all might seem anal, but I had engine one time where the pin to pin bore clearence was good but during starter spin over to get oil pressure the pin bore aluminum galded to the pin and actaully locked the motor down, and after that I always used Goodson Tool press fit oil, the more engines you build the more things will/can show their ugly heads, and the more anal one will get to fend off even he most unuseal issue.
And one is correct to beleive, that with new bushings it would almost always require honing to fit.
Also worth mentioning you sometimes have to hone a piston for a pin fit as well, I order all my JE race piston without pin fit and do it myself, and sometime even on a stock off the shelf piston I don't like the fit between the pin and piston's pin bore hole and will hone them just a tad to get the fit I'm looking for, this would apply to either a press fit or flaoting pin application. Another thing to keep a eye on is lubricatin during assembly between the pin and the auminum of the piston, I use a special lubrication oil for this made by Goodsen Tool, it is specially made for this, it spray in thin like a regular lubricating oil, then thickens up to stay stuck on the parts untill inttial crank up is done. This all might seem anal, but I had engine one time where the pin to pin bore clearence was good but during starter spin over to get oil pressure the pin bore aluminum galded to the pin and actaully locked the motor down, and after that I always used Goodson Tool press fit oil, the more engines you build the more things will/can show their ugly heads, and the more anal one will get to fend off even he most unuseal issue.
Hap Waldrop
Yoda
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Morris said:
Its too thin it drains off, I would use that stuff and then put a pastic bag over the engine at stopping poit at day's end, come back in the next morning to find a puddle of it in the bottom of the plastic bag wrapped around the engine, that told me it was not staying put. The CRC assembly lube is readily availabe at NAPA stores, its a pure moly product and more like cream than a liquid, it stays put where you put it. Most pro engine builder swear by the stuff, I even got some Red Line assembly lube and it sucked compared to the CRC stuff.