Connecting Rod issue
12-02-2010, 07:08 AM
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Connecting Rod issue Hey guys new to the forum with a question. I didnt know which engine forum to post this in. Anyways my buddy is building a 02 6.0L but as a LS3 clone. Well he bought these pistons http://www.summitracing.com/parts/ST...n/?prefilter=1 thinking these would work. On the website it says pin size .943 and press fit. Well when he brought them up to the machine shop when they went to put them together the guy said that the pin measured .943 and that the rod hole also measured .943 so the pin slid in perfect. I figured the hole in the rod would measure a lil under .943. Well the pistons did come with clips. We are confused because we thought it said they were press fit. Anyways getting to my point the machine shop put the pin in with the clips and said run it. I thought with any pin that doesnt get pressed in you need a bushing in the rod. The way it is set up right now its metal to metal contact in the hole I am very weary about running it like he said. Any ideas on what to do or if I should run it. This is our first time messing with the LS based engines. Thanks Guys!
12-02-2010, 09:41 AM
#2
I wouldn't run it like that. I've heard of a lot of "ma' and pa'" rebuilders doing that, but most performance shops wouldn't do that.
See if the old pins would work. They should measure larger than the pin bore in the rod so your friend would have his press fit, but they may need to hone the pistons to regain the piston-pin clearance.
See if the old pins would work. They should measure larger than the pin bore in the rod so your friend would have his press fit, but they may need to hone the pistons to regain the piston-pin clearance.
12-02-2010, 10:25 AM
#5
Correct. The piston does not care. As long as the pin spins freely, there should be no issue. You could go into pin bore clearance, but that is way overthinking this one. IMO they are prob a newer rod anyway, so it is accidentally the correct setup.
12-03-2010, 11:21 AM
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Well the rod measures .943 and it doesnt have a bushing so the only thing I can think of is this connecting rod must be for a press fit which is what it was orgionally and these pistons are for a rod that has a bushing that has a .943 inside diameter. The only question is trying to find the GM rod that has a bushing in it and has a .943 inside diameter
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12-03-2010, 12:13 PM
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Hey guys sorry I think I got my facts mixed up. I just talked to him an its a 6.0L motor out of a truck that he did an engine swamp in. Would that be the LQ4 or LQ9?? I am still trying to figure out these newer engines I know more about the older ones. Its a iron block that hes making a LS3 clone out of. I apologize for the mix up. Does this make a lil more sense now? Thanks for your patients guys!
12-03-2010, 12:47 PM
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Ok now I am really a complete idiot I think I figured it out. The aftermarket forged pistons are a pin size of .945 so you could only use them as a press pin on a stock rod. But if you bought an aftermarket rod you would use it as a floating. So if he got stock rods that were after 04 they would have the bushing and they would be .943 inside diameter and he would be able to use the pistons he bought ? And you cant use a stock piston on an aftermarket rod unless it was before 04 with the press pin but then you would have to have the pistons machined for the clips and use it as a floating piston I dont know if anyone would do that? Am I getting warmer??
Last edited by 66NovaSS327; 12-03-2010 at 12:49 PM. Reason: messed up
12-03-2010, 01:09 PM
#12
Ok now I am really a complete idiot I think I figured it out. The aftermarket forged pistons are a pin size of .945 so you could only use them as a press pin on a stock rod. But if you bought an aftermarket rod you would use it as a floating. So if he got stock rods that were after 04 they would have the bushing and they would be .943 inside diameter and he would be able to use the pistons he bought ? And you cant use a stock piston on an aftermarket rod unless it was before 04 with the press pin but then you would have to have the pistons machined for the clips and use it as a floating piston I dont know if anyone would do that? Am I getting warmer??
Depending on the year of production, you can find OEM rods with either the press fit or floating pin, so obviously there are OEM pistons out there with grooves for those rods with the ends bushed for floating pins.
The aftermarket also offers rods for either press fit or floating pins, so you can mix and match any combination as long as the pins match up. You can actually use a SCAT rod (which can have a pressed pin) with a stock piston if you wanted to, or an aftermarket Wiseco forged piston with a stock floating pin rod.
As far as the pins are concerned, the important part is that you match up the dimensions (diamater and length) as well as design (press or floating).
12-03-2010, 01:14 PM
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So yeah now we are just going to get stock rods after 04 that have the bushings and we should be all set since the pistons he got use the floating pin and measure .943. Which obviously will work with the stock rod after 04. Thanks again for your time and patience guys I have learned quite a bit even know its not much haha
12-03-2010, 01:17 PM
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Part of it was my fault I was misunderstanding the situation. Its an 02 so thats why the wrist pins were pressed in. The pistons we got are only made to go on after 04 rods from what I have just learned... I believe.
12-03-2010, 01:18 PM
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Thanks for the info we know someone with a used set for 80 dollars and then will have them checked out to make sure there ok. Its kind of a budget build.