Costs of press fit vs. floating...

[Ben A...]

I'm ordering a set of Speed Pro H116CP pistons for a stock LA360 rebuild--Street car.
Those pistons can be press fit or floating.
Trying to go whichever route is less costly...

I assume to go floating I would need to buy and install bushings on the rods? Is that hard? Do I need special tools?
Am I better off just getting a machine shop to press fit the pistons?

Thank you,
Ben

 

[JBurch]

Press them on and don't give it another thought. Full floating's only advantage is if you are constantly into the engine

 

[yellow rose]

Press them on and don't give it another thought. Full floating's only advantage is if you are constantly into the engine

That’s not true. Why did the 340 get floating pins? They didn’t expect the end user to be working on it all the time. Most of that stuff never saw a track. A lot of that stuff towed boats and motorcycles.

A floating pin is an upgrade. If you have bushed rods, have the pin ends checked for size and float them.

If you have press fit rods, have the shop measure the pin ends and if needed, hone them to get .0008-.0010 press fit and let them press them on. If they won’t verify and size the pin end for size and press fit, find a better shop.

 

[Ben A...]

That’s not true. Why did the 340 get floating pins? They didn’t expect the end user to be working on it all the time. Most of that stuff never saw a track. A lot of that stuff towed boats and motorcycles.

A floating pin is an upgrade. If you have bushed rods, have the pin ends checked for size and float them.

If you have press fit rods, have the shop measure the pin ends and if needed, hone them to get .0008-.0010 press fit and let them press them on. If they won’t verify and size the pin end for size and press fit, find a better shop.

The LA360 comes stock w/ press fit rods though correct? The H116CP pistons come with wrist pins, would those not be suitable for press fitting?

 

[RustyRatRod]

Yes the pins that come with those pistons are fine. Press them on and go.

 

[Ben A...]

Yes the pins that come with those pistons are fine. Press them on and go.

Thanks Rusty!

 

[MOPAROFFICIAL]

The press fit is at the rod, piston floats.

 

[4spdragtop]

Pros vs cons?

 

[moper]

360 street engine presses is fine. If you were going to race it or beat it on the street, I’d have the rods bushed and float them... but I’d probably be telling you to buy s better piston anyway.
Pressed pins can and do walk under heavy abuse.

 

[nm9stheham]

Pros vs cons?

As above... if you are being aggressive with lift and being precise with chamber sizes, compression ratio, etc., then taking the pistons on and off the rods a few times to make adjustments is one area where floating pins helps you. If you press the pins in, and have to make a change to the pistons later, pressing them off always presents some chance of damaging them.

 

[RustyRatRod]

Pros vs cons?

It's arguable. I've always read in the old real world mechanics books that full floating pins remove some of the load from the piston and allow a little more freedom thereby removing some stress and freeing a little friction. Seems plausible to me. Of course, there's the other end of it, the ease of assembly. You can bet you butt though that it's no coincidence that all of the real performance engines from the factory had floating pins. Also, MOST older (early 60s and prior) passenger car and light truck engines had them as well. The 1956 331 truck Hemi I have had floating pins and I utilized them in the rebuild.

 

[Dartfreak75]

I just ordered the same piston last week check out this seller they come with moly rings, and pins for 315 shipped. Speed Pro Chrysler/Dodge 360 Hypereutectic Flat Top 2VR Pistons+MOLY Rings +30 | eBay

 

[Krooser]

The ex-nascar high zoot Pankl rods I have were installed with a press fit. What's old is new again.