4A-GE MK1 Engine Piston to wall clearance??

SW21T · 10-25-2009, 02:29 PM

I bought a set of pistons (# PS2012A) and I have no clue how to get the piston to wall clearance so I can get it bored out. They are 0.20" over the standerd size. I have looked and found nothing.

Thanks

328FTW · 10-25-2009, 07:58 PM

Not going to pretend to be an expert but it depends on what you are doing and what pistons you use. If you are racing the clearances are a bit different (in fact I think a bit "looser" than a tight road setup, not sure) and if your pistons are forged/hyper-eutectic/cast it makes a difference to how much they expand and your given clearances. This should be the sort of stuff the engine builder runs over with you and can explain so I'll lay off the heavy theory of different piston types and how they expand lol.

Sang · 10-25-2009, 08:17 PM

It shouldn't matter what you are using the pistons for. Some claim they shave an extra bit out of the bore if it's in a boosted application.

Point of the matter is, your pistons should have came with a spec sheet for you to give to your machine shop, along with the pistons and block. The manufacturer bases these clearances on the metallurgical properties of the piston itself.

328FTW · 10-25-2009, 08:23 PM

Quote:

Originally Posted by Sang

It shouldn't matter what you are using the pistons for. Some claim they shave an extra bit out of the bore if it's in a boosted application.

It's an opinion thing some swear by certain methods some claim it's rubbish in the end if they fu** you land up with pistons seized in the bores

. But yeah there should be a spec sheet about somewhere even if you have to look it up or ask the engine builder to get a hold of it.

10-25-2009, 02:29 PM	#1 (permalink)
SW21T 400HP 3rd gen?? Join Date: Nov 2008 Location: Washington St Posts: 1,853 Thanks: 143 Thanked 32 Times in 30 Posts iTrader Rating: (18/100% )	Piston to wall clearance?? I bought a set of pistons (# PS2012A) and I have no clue how to get the piston to wall clearance so I can get it bored out. They are 0.20" over the standerd size. I have looked and found nothing. Thanks

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10-25-2009, 07:58 PM	#2 (permalink)
328FTW Crazy Nasty Honey Badger Join Date: Aug 2008 Location: New Zealand Posts: 5,222 Thanks: 24 Thanked 266 Times in 239 Posts My Google Map iTrader Rating: (1/100% )	Not going to pretend to be an expert but it depends on what you are doing and what pistons you use. If you are racing the clearances are a bit different (in fact I think a bit "looser" than a tight road setup, not sure) and if your pistons are forged/hyper-eutectic/cast it makes a difference to how much they expand and your given clearances. This should be the sort of stuff the engine builder runs over with you and can explain so I'll lay off the heavy theory of different piston types and how they expand lol.

10-25-2009, 08:17 PM	#3 (permalink)
Sang Turtle Join Date: Jul 2006 Location: FL Posts: 4,096 Thanks: 18 Thanked 267 Times in 246 Posts iTrader Rating: (5/100% )	It shouldn't matter what you are using the pistons for. Some claim they shave an extra bit out of the bore if it's in a boosted application. Point of the matter is, your pistons should have came with a spec sheet for you to give to your machine shop, along with the pistons and block. The manufacturer bases these clearances on the metallurgical properties of the piston itself.