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Discussion Starter · #1 ·
Hi guys, I am finally able to start on the shortblock. I will be using the standard GTE pistons and rings and a rehone, beefed up rods and beefed bearings.
I will be running a 76mm GT42, stock head, crower valve springs, reverse staggered HKS or straight Crane 280's, 1000cc injectors with 30 psi boost on an AEM. I don't know what kind of HP to expect though.

Fisrst thing first:
How much must piston-wall clearance be. Is 0.0055- 0.0060 O.K.?
I have been told that the stock GTE pistons don't expand like the uncoated performance ones because of the coating and oil gallies. Anyone has some insight into this?
 

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What's up with all these rebuilding engine threads lately. Maybe it's cause I need to rebuild mine also and I'm just noticing all of them at once. Did your shop turn up the boost controller on your engine and blow it up like they did mine?
 

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feeding your habit
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go by the FSM for piston/wall clearances.
 

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98mkiv said:
go by the FSM for piston/wall clearances.
Good advice; just not sure you will be able to meet the FSM standard after honing. Need to have a good discussion with your machinist.

Ken.
 

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feeding your habit
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yeah, re-using pistons has never seemed right to me if you touch the bores while they are out. New OEM pistons are not as expensive as you'd think.....

-M
 

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Cheifbootknocka
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I think a good reason to use stock pistons is that they dont have the clearance/ piston slap that the aftermarket pistons generally have.
 

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TooJayZee said:
I think a good reason to use stock pistons is that they dont have the clearance/ piston slap that the aftermarket pistons generally have.
Not saying he shouldn't use stock pistons. I was saying I'm not sure he can meet the FSM piston/wall clearance standard after he has the bores honed. Hopefully, he can, but I doubt it if he intends to meet the FSM standard.

Ken.
 

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Discussion Starter · #8 · (Edited)
Begone: Nopes, I have final say on everything they do on the car, from boost, timing, etc. That's why I do almost everything on the car. When it goes BOOM, I will be the only one to blame.

Ken: That's true, I did not consult the FSM because of that issue. I spoke with the machinest, about this, he's not sure. MAx clearance he'll do is 0.006. Any bigger and I'll have to get those good looking CP pistons.

I haven't read much on the amount of clearance people run on 600+rwhp engines
 

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Cheifbootknocka
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KenHenderson said:
Not saying he shouldn't use stock pistons. I was saying I'm not sure he can meet the FSM piston/wall clearance standard after he has the bores honed. Hopefully, he can, but I doubt it if he intends to meet the FSM standard.

Ken.
I agree. I was just blurting out my opinions. Once you hone the wall your clearance went out the window. Or does toyota offer a overbore piston I wonder ?
 

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Discussion Starter · #10 ·
A little update:

The new pistons turned out to be wider than they are supposed to be. They are still the stock bore, but a few thousands wider.The fit snugly inside the cylinder. They fit perfect after the honing. I'll stop by the machine guy tomorrow with a stock piston to compare them.

Maybe Toyota makes them a couple of thou bigger to allow for honing? It looks like it.

Also the machinist told me that the cylinders taper as they go down. There's a difference of 1 thousand from top to bottom. Maybe someone knows more about this.
 

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Cheifbootknocka
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Grumpy said:
Maybe Toyota makes them a couple of thou bigger to allow for honing? It looks like it.

Also the machinist told me that the cylinders taper as they go down. There's a difference of 1 thousand from top to bottom. Maybe someone knows more about this.
I hope toyota does make oversized pistons. The dealer should be able to tell you if thats what you got. The cyl bores generally do taper or so my machinist tells me on the 10+ motors ive built.
 

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Boost4fun
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That would be sth new to me. According to my info Toyota doesn´t sell (at least officially) oversized pistons, only complete shortblocks...Unfortunately
Would be interesting to know.
Gerd
 

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Discussion Starter · #13 · (Edited)
Ok, we measured the old pistons and the new ones.
The old ones are 3.380"
The new ones are 3.385" so a 0.005" difference.

This brings a new problem on the table. The OEM pistons rings that I bought have 0.032gap. I can't find anything on ring gap on the forums but the FSM states a max gap of 0.0394 on the 1st compression ring. My problem is what is acceptable and what's not.
 

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Discussion Starter · #15 ·
Sorry, forgot about the thread

The clearance is 0.006". Total bore is 3.391". Piston size is 3.385"
 

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Discussion Starter · #17 ·
I contacted Total Seal regarding a custom gapless application. There's a shortage of Redline Assembly lube on the island. I am waiting for for the redline shipment to arrive so I can start assembling the engine.
 
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