Piston pin questions

[iTurbo]

I know this is a bit of a newb question, but can the factory rods be setup for floating pins if they were originally press-fit pins? Do they have to bore out the small end in order to put the bushing in, or does it just press in? Can the rod strength be compromised if going with a large .927 pin floating pin? What if you wanted to go with a smaller .866 pin? Would you just need the appropriate bushing, or does the bushing just get honed out to accept whatever pin?

[zin]

Any rod used with floating pins will have to have ther small end bushed. Most can be converted without sacrificing too much strength.

The bushings are normally pretty thin, and are there mostly because of material compatibilities, steel on steel would gall.

Mike

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Any rod used with floating pins will have to have ther small end bushed. Most can be converted without sacrificing too much strength.

The bushings are normally pretty thin, and are there mostly because of material compatibilities, steel on steel would gall.

Mike

[iTurbo]

I've seen factory floating pins in the 2.5L TI and 2.2L TIII motors I've taken apart. But all the 2.2L TI/TII motors I've had apart had pressed pins. I'm about to start on rebuilding a TII motor that had LW rods and pressed pins in Mahle pistons. I had the machine shop recondition a set of early HD rods and swap the pistons onto them for a cheap rod upgrade.

Problem now is that ONE of those pistons didn't work out so well and after pressing the pins back in it doesn't pivot on the pin nicely and 'creaks'. I may have to buy new aftermarket pistons at this point, which would surely come with floating pins. On top of that, it seems that all the readily available aftermarket forged pistons come with larger pins (.912 or .927) and not the standard .901 size. So I'm wondering what to do at this point....I have no problem investing in aftermarket pistons/rods, but I would rather do that with my 16v motors. As far as the 8v motors, I'm trying to save money and go with good stock stuff.

[turbovanman²]

Depends on how much meat there is on the big end. If you want to use earlier HD rods, just leave them be and push the piston pin in. You'd need a pretty thick bushing to knock it down to .866, if wanting to do that, just get some Eagle SRT rods off the SRT forums, cheaper way to go.

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It creaks? Have the machine shop hone the piston pin bores. Look at high HP V8's, they don't have bushed rods, and factory TII's are supposed to be floating, so if they aren't, then someone has been changing things around. If your having creaking isses on the bushing, then have the machine shop either replace the bushing or lightly hone it.

[iTurbo]

This TII that I'm about to reassemble is.....a little different.

I bought it from Dave Grove back in '99. I bought it as a Turbo II long block. It had the cross drilled head/block, forged crankshaft etc....but it had lightweight rods with press-fit Mahle pistons. According to Dave from our phone conversations, it was from Mopar Performance and used as a test mule for MP parts! It was my first eBay purchase ever!

So now that I'm rebuilding it, after many many thousands of miles of use and spinning a rod bearing over revving it racing a VW, I found that it had LW rods with pressed pins. I had a set of the early HD rods so I had the machine shop recondition them, but one piston didn't go so well and it 'creaks' when you pivot it on the pin after putting them together. I have found a few extra 8v swirl standard size Mahle pistons in my stash, so I'm hoping I can get by without having to buy aftermarket pistons... Will update this thread on how that goes.

[zin]

The Shelby TII engines didn't have floating pins because the bottom end was actually an early TI with a TII "top end".

Mike

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The Shelby TII engines didn't have floating pins because the bottom end was actually an early TI with a TII "top end".

Mike

[iTurbo]

Yeah, that is what confused me. It was all factory TII stuff (forged crank, cross drilled) except for the rods and piston pins. Who knows as far as what Mopar Performance or Direct Connection was doing back then though. Perhaps it was just something they threw together as a test mule.

[turbovanman²]

This TII that I'm about to reassemble is.....a little different.

I bought it from Dave Grove back in '99. I bought it as a Turbo II long block. It had the cross drilled head/block, forged crankshaft etc....but it had lightweight rods with press-fit Mahle pistons. According to Dave from our phone conversations, it was from Mopar Performance and used as a test mule for MP parts! It was my first eBay purchase ever!

So now that I'm rebuilding it, after many many thousands of miles of use and spinning a rod bearing over revving it racing a VW, I found that it had LW rods with pressed pins. I had a set of the early HD rods so I had the machine shop recondition them, but one piston didn't go so well and it 'creaks' when you pivot it on the pin after putting them together. I have found a few extra 8v swirl standard size Mahle pistons in my stash, so I'm hoping I can get by without having to buy aftermarket pistons... Will update this thread on how that goes.

Have the machine shop check that piston/rod and hone as necessary.


The Shelby TII engines didn't have floating pins because the bottom end was actually an early TI with a TII "top end".

Mike

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The Shelby TII engines didn't have floating pins because the bottom end was actually an early TI with a TII "top end".

Mike

Interesting info.

[iTurbo]

Well, thanks to my seemingly infinite stash of turbo Mopar parts, I was able to find some extra stock/standard size late model Mahle 2.2L turbo pistons (for 782 head and press pin). I dropped off three extras today for machinist to pick through and find the best one, so it seems I may have escaped biting the bullet here..

[zin]

Another case of "saved by the parts stash"!

Mike

PS since you've been rummaging through pistons, if you have a piston/rod assembly you'd be willing to sell, I've got a good home for it, PM me if you do, it's for an 86glh.

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Another case of "saved by the parts stash"!

Mike

PS since you've been rummaging through pistons, if you have a piston/rod assembly you'd be willing to sell, I've got a good home for it, PM me if you do, it's for an 86glh.

[iTurbo]

I do, as I'm pretty sure I'll have two good piston/rod assemblies left over after the machinist is done.

The extras I have are originally from an '88 2.2L Turbo I motor. Cast Mahle pistons in standard size attached to the factory lightweight rods. I have a couple extra later model HD TII rods too if you are needing it with that instead.

You wouldn't believe how many times I've been saved by the parts stash! Helped local friends a few times too!

[zin]

Saving me in a way too!

The LW rods are what I need, this is a Log T1, so same bottom end as a Shelby TII, the HD rod would throw off the balance even more than the LW rod. I just need it to make one of my engines "whole" again, the original engine from my GLHt developed a pin noise, which is much better than the bearing noise I thought it could be initially! But after driving it a few hundred miles and noticing it would come and go with load, I realized it wasn't an engine killing event and "Parked" it until I could make it whole again

So, shoot me a PM with the total to 92840 and I'll send you some $$ via PayPal, if that suites you.

Mike

[4 l-bodies]

Mike, if Jeremy doesn't have anything for you, I know I have some low mileage LW 2.2 press pin piston rods assemblies. LMK.
Todd

[iTurbo]

Well the machine shop called me back yesterday. Apparently the 'creaking' piston/rod assembly was due to the rod itself. He tried to swap another piston I had and the same thing happened.

So now I'm looking for an early HD rod, perhaps two just to be on the safe side. I'm almost positive the part number ends in 385. Mike, as soon as I'm through this ordeal and in the clear, I'll let you know what extras I have. If you need one really soon, you might contact Todd.

[zin]

I'll talk to Todd about a piston/rod assembly, sorry to hear it's being a PITA...

Mike