Stock Pistons "vs" Non forged .020 pistons

[supraguy31]

Hey yall, I just picked up a 7MGTE bottom end yesterday and After Tearing it down, I noticed that everything in it was really really clean. When I picked it up, the guy that I got it from said that it had a Spun bearing and it has 200,000+ miles on it.

Well, One I got the oil pan off, I noticed that the Oil Pump looked really clean (Nothing in the Filter), I started to search for the one rod that has the spun bearing and come to find out its not a Spun bearing, Who ever went into this motor forgot to Put Rod Bearings inside of the #6 rod

Pulled the #6 Piston out of the block and no Rod Bearing on either side. Pistons are in excellent shape, I checked the cylinders and It looks as though its been Honed out as I can still see the Hone marks in each cylinder and the rings are still in great shape. (Spring out really well)

My intentions were to Get this Engine Bored out and install .020 non forged Pistons, Since this engine has already been through and everything is Factory Toyota, would it be better to stay with the Stock Pistons? Ive heard that stock Pistons can take alot of boost and most of the time they are better than most of the non forged Pistons that are out there.

Do .020 Pistons really make that much Difference if they are non forged?

Im going to put my new Crank into this Block with my rods and Bearings, All I thought about doing is just installing those Pistons on my Rods, Doing a Light deglaze of each Cylinder since Ive pulled all the pistons and cant remember which cylinder they go into and re-assemble everything.

Any Recommendations would be greatly Appreciated

Robert

 

[Jaguar_5]

The .020 has nothing to do with it, you want to take off the minimum amount needed to get a proper clearance between the piston, and cylinder walls.

If you have to get new pistons, just get Wiseco forged pistons, from summit racing, for about $560 shipped

 

[supraguy31]

Well, I dont have to get new Pistons, The Block already has Pistons in them when I got it. Basically I got a Complete bottom end. Cylinder walls are in Perfect condition and I can still see the Hone marks on the Cylinder walls. (Someone did a Ring Job and forgot to Put rod Bearing Back into #6)

What I want to do is Use my new Crank since the one that is in there #6 Journal needs to be looked at, Use my New rods that go with the new Crank that I have, Just pull the Stock Pistons off the old rods, Insert my new Rods to the Stock Pistons, Lightly Deglaze the Cylinders and Assembly everything.

Basically, Im going a Complete rebuild but Im using the Stock toyota Pistons instead of taking the Block to a Machine shop, Having it Bored out 20 over and using non forged Pistons.

 

[Tim]

I doubt that someone would be stupid enough to not put the rod bearing back in. Chances are that that block had already been taken apart and when they found the problem, they just threw it back together and sold it..

 

[supraguy31]

It was in a Running car, The guy I got it from Bought the car and Boost 23 PSI for about a week, Knock got worse and he pulled the motor...

 

[starscream5000]

If the cylinder walls look good, how do you know that the block hasn't been bored out already and has .020 over pistons in it? Don't buy any pistons until you take it to a reputable machinist and have them tell you what you'll need as far as bore goes, along with oversized rod and main bearings (thrust washer too) .

 

[supraguy31]

Here are the Pistons that I pulled out of the motor. About 3 minutes each to clean the Pitons. Im not going to use the crank or the rods from this motor, I have my own rods and crank with Bearing that Im going to use. All Im going to do is use these Pistons instead of the .020 over one I have since these are what came out of it.

 

[Supracentral]

http://www.supramania.com/forums/showpost.php?p=180360&postcount=10

...

 

[Doward]

Measure the cylinder bores and determine your piston-wall clearances.

You want to find out first if the bores are good (*edit* as in, make sure the block didn't need a bore in the first place due to excessive wear, but the PO just honed and ringed the pistons anyway) - I *NEVER* trust another's word when it comes to what was done, and whether it was done right.

 

[NewWestSupras]

As long as your piston-to-bore clearances are within spec, the use of non-forged stockers should be fine if your not exceeding much over stock boost levels. Coating the pistons and balancing the bottom end are always good practices. Judicious choice of rings is important as well. All these factors are relevant to a long-lived rebuild, gl!