Block .40 over, Throw it away?

[Snake Killer]

Recently the motor in my 87 went south for the winter, and now i'm rebuilding.

I bought the car used with a "fresh" motor from a machine shop, and the previous owner said he knew nothing of the motor build, build quality, ect ect, with turns out to be ****, but after pulling the motor i've discovered its been punched out to .40 and the pistons have big cracks in them.

The cylinder walls look fine, crank needs to be turned, needs new bearings all around, pistons, rings, probably a crank depending on how bad it is, but every machine shop i've called has just told me to throw away the motor? They said if I'm trying to make any boost on this block, with it being over that much, its going to go kaboom, and I wont be happy.


So i'm asking anyone and everyones opion on the matter, is it worth putting back together, or am I doomed to find a short block and start all over?

 

[SPOOLN]

These 109s are very strong block, I would find a good machine shop. Have them hone and measure the cylinders. I would have it magnafluxed for cracks around the webbing. Only thing is, why did the piston have cracks. Thats what i would look for. Where both head gaskets blown? Something to consider. If all is good i would use file fit rings and build it.

 

[TR Custom Parts]

What about sleeving the cylinders??

 

[turbot2112]

i have a jasper motor in my car and im pretty positive its 40 over. the motor has been very good to me and im running around 22 and sometimes 24 pounds of boost . was told that all jasper 109 blocks come 40 over. if i were to break it tommorrow i would get another one.

 

[MSA231V6]

Keep it. A friend of mine is running consistent 10s (and has been for a while) on a 109 block that is 40 over and is using a non-turbo crank. These motors will last if you treat them right.

 

[Blue87T]

I bought a cheap ATK engine and its 40 over... runs ok but I havent had it to the track yet.

 

[SloGN]

0.40 engine

what it boils down what type of pistons where in that engine, how much knock did it see those are things to consider when a engine fails in these cars.


my current engine in my car is .40 over with about the same mods and have beat the living crap out of it. and i recently pulled the motor and put on some ported irons and just freshened up the bottom end with new bearings.

a friend had a .60 over motor and ran it for a while. till it got a rod knock. like the others guys have said have a machine shop check to see if the bore is still true @ .40 over if it is i would hone that mother and get some decent pistons and ride the piece til it blows again.

 

[turbot2112]

also, people have said that with the cylinder walls being bored .040 they will heat up quicker and you get more knock with less boost. makes sense , but i have never seen a diffrence .

 

[Ormand]

also, people have said that with the cylinder walls being bored .040 they will heat up quicker

That makes NO sense to me. The heat comes from the combustion chamber. With thinner cylinder walls, the coolant will take heat away quicker, cylinder wall temps should be LOWER where the metal is thinner. Whoever told you that apparently has never taken a course in heat transfer. Or maybe he/she took the course in Las Vegas.

 

[buickpower]

I think he means the engine as a whole will heat up somewhat more quickly, which it will, but like you say not necessarily the cylinder walls. Thin walls will transfer heat more quickly, but that heat gets transferred to the coolant, which as a result gets heated more quickly. Steady state operating temp on the other hand, shouldn't change drastically unless the cooling system is now incapable of handling it's dissipation duties.

In regards to the original poster, your block should be fine for operating temp wise unless you have a really clogged radiator.

 

[Snake Killer]

Well i'll k eep the block then, thanks for all the replies.

The answer to what kind of pistons they were is, i frankly dont know.

I know the guy who built the motor was on a budget, and they dont look like any pistons i've ever seens ( CP pistons in my SRT-4 ) they look stock as hell just bigger, rings looked like they were used, and just not a well put together motor.


I'll be doing things right as this is my dream car, and i've got alot of life left, i'm only 20~, i figure i'll have the car for another 80 years.

 

[Mike Licht]

Sounds like it had a Hyper or cast piston. If you replace them with a forged piston you will need to hone out a few thousands for the extra clearance will will fix it up I would do that
Mike

 

[Snake Killer]

I would rather do that than throw the block away.

Consider it done, and I thank everyone for thier responses.

 

[ronbuick]

I have a .040 in my wagon, seems to be fine!

Ron