Odd Bore Job

[graipaip]

Ok all you Engine guys. Come across something today kinda got me stummped and also interested all at the same time. Got a 327 in on trade sapose to run ( never herd it run ). so me being me i tore it apart to see how i screwed my self. LOL well all looks good has some good parts to it BUT. 1,3,5,2 are .030 and 4,6,8,7 are standard. Now this engine has been balanced and there is no signs of it ever comming apart from a blow up or anything. So i am trying to figure out is this some old guys idea gone wrong or is it some sorta racers way of making power or Lots of RPM.
Not sure where it would help anything or do any good but just seams to be to " on purpose " to be a mistake on the builders part. Come on weve all built an engine with a case of beer before but could you really screw one up the bad and eavenly all at the same time.

[msims]

is it .030 or .003 over

[8I MALIBU]

Could just be a remanufactured motor from autozone or oreillys. I know when I worked at the Aaron's Automotive plant here in Joplin they did stupid stuff like that all the time.

[graipaip]

Its stamped .030 on the 4 of the pistons. Just kinda odd that eaven with there being diffrent size pistons in it i have seen that. But to be placed in the block the way they are is where its strange to me. Then to have the 2 bolt to 4 bolt conversion on it ( which i did not state above ) and to be all balanced out that can't be a Autozone motor.

[msims]

are u sure the 4 pistons are standard or are they .030 tht had ink marking numbers rather thn stamped # on thm??? the ink burned off

[graipaip]

got out the mic 4.00 on the standard and 4.279 to 4.299 on the 30 over side i dont have an actual bore scope all i could use was my mic on the top ridge. There is no build up on the ridge as the motor does not have much run time on it.

[graipaip]

here is a pic of one of the pistons Stamped.

[toddmoore4114]

L2256 trw is a 350 piston.......

[graipaip]

Yep it is. Casting number shows 68 to 79 350 or 327 ( 3970010 ) i just went with the 327 just because i had my hopes up when i got it. lol
Not going to pull the crank out to check any further at least not till i get to here it run then maybe i will.

[msims]

4.00 then .030 over ould be 4.030 not 4.279 - 4.299 ,,,you mean 4.0279-4.0299
????

[8I MALIBU]

Yea sounds like that was definitely done on purpose. I wonder how they got it to balance out with different size pistons?

[secondwindracing]

the way you are measuring it you mise well use a tape measure. you have to use a dial bore guage to get the rite reading.dave

[ssbarracudafan]

This is common for a part store reman.. As far as balancing, that is easy for a shop. It use to be a way to cheat on a "stock" class car, leave #1 stock and bore the rest. Becouse tech would only check #1, thats why now they check cylinders at random.

[amcamx]

What you can get by with, on an internal balanced motor, seems to be a lot.
Heavier .030 over popup domed pistons, and not be balanced, and then take it to 8,000rpm, etc.
I ran a 273 crank in a .040 over 340 motor for 18 years, street, and strip use. It did shake some at 7,200rpm.
I took a Chev 400 external balanced motor, in to be balanced, and they had a fit. I had damaged a piston, and bought a new one, and it was 31 grams too heavy. That is about an once, and they said the piston cannot be lightened that much.
The shop said that the pistons can be heavy or light, but they must be the same.
How can you call a Chev 400 balanced anyway, with over three pounds on the outside of the Flywheel.