Rods and pistons?

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Jul 5, 2015 | 03:39 AM

HappySalesman

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Rods and pistons?

Hey all, looking to do a bottom end rebuild in my z, and ran into an issue.

I want to replace the piston and rods with forged parts, to give me a really solid foundation for my build.

However I can't really seem to find any pistons that fit the stock bore? The closest I saw was 3.903. If I wanna do this build, am I gonna have to get an overbore done?

Jul 5, 2015 | 04:42 AM

J0SH

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Normally people bore out a stock bore when they go to a forged setup. The stock cylinders never seem to be completely straight.

Jul 5, 2015 | 11:44 AM

HappySalesman

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Ah okay. Is it common to go with longer rods as well, or is that just for people wanting a stroker setup

Jul 5, 2015 | 12:36 PM

KCS

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Depends on the piston, but usually you will want to use a 6.125" rod. The Scat I Beams are nice for mild builds (<600rwhp) and are pretty inexpensive.

Jul 8, 2015 | 11:36 PM

HappySalesman

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this will probably sound really nooby, but with the slightly longer rods, what overall would change in the engine? I know obviously the piston will sit .127" higher in the cylinder, but at that point am I looking at having to flycut pistons or add valve reliefs?

Jul 9, 2015 | 03:32 AM

Quick Ranger

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Quote:

Originally Posted by HappySalesman

Most aftermarket pistons will be set up to use a 6.125 rod with a .927 pin. They will also have valve reliefs already.

Jul 9, 2015 | 09:04 AM

KCS

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Quote:

Originally Posted by HappySalesman

Stock rods are about 6.098" center to center, so a 6.125" rod is actually only .027" longer.

Aftermarket forged pistons will usually have a reduced compression height (distance from wrist pin centerline to top of piston) at about 1.300-1.305". They normally already have valve releifs cut into them, so you don't normally have to worry about that.