Masive knocking noise and spark plug all oily

**Scottydoggs** · 11-19-2011

its going to blow up again but faster this time, you CANT run different compression pistons, its wont last long. every piston is fighting with the others ones, different weight, different compression, it wont work.

**OH4CompG** · 11-19-2011

Engine is out of balance. Extra wear and tear on bearings. Speaking of which are you using correct bearings while you're swapping pistons left and right? KR potential will be higher with the higher compression pistons. Not only is it a tuning nightmare, eventually it will grenade again.

**chunky** · 11-19-2011

what the fvck is wrong with you??? how are you smart enough to turn a wrench, but can't understand this stuff? go cut a spoke out of one of your wheels and drive on the highway and see is you notice the weight difference.

**Z34Phoenix** · 11-19-2011

I dont understand this... like said above...

FYI just weighing the pistons doesnt mean they will be in balance. remember this is a rotating assembly. its balance that is the issue. if the rods are diff then they wont balance the same. and if the piston has more weight up top or bellow it can throw off the balance too.

you need to run all the same pistons in the engine. no exceptions.

dont even try to start that motor. put all the same piston in or swap the short block. you may get a little time out of it but you will just be repairing it again. do it right and be done. also if your running a stock PCM/tune then the car should be stock. pulley pistons ect.

PS.
the smart A in me says for you to just stop! sell the car and get a one speed huffy bike. i just dont understand why someone would do something like this.

**guimond47** · 11-19-2011

Fine ill throw gtp pistons in the back too then . Does the crank matter if its gt or gtpp?

**Scottydoggs** · 11-19-2011

i give this guy a A for effort, most who cant identify where the cam is or other parts names, well they most often tear it all apart, and are then stuck on how to put it back together.

in all seriousness, no one here is steering you in the wrong direction, scrap the bottom end all together, buy a used short block and fix it one time and do it the right way, and your hands will stay clean for quite some time.

all this mix matching of block internals will only have you doing all this work again in a short amount of time, and with all the money you are wasting on gaskets and fluids, you could of have had a good running block.

**Scottydoggs** · 11-19-2011

let me add, when we do a back yard rebuild with these engines they never last long, unless you drop off the block and have it align bored the (crank journals) and your blocks piston holes must be all sorts of messed up, and would need to be bored .30 over, and new rings installed, and all new bearings. in the long run a lot of us get used blocks, and mod the living day lights out of them, and they hold up.

a used block is way cheaper than a proper rebuild, thats just a fact.

**guimond47** · 11-19-2011

Im selling the thing so idc.. Does gtp pistons hold up wit a gt crank?

**1999BLKGTP** · 11-20-2011

Please do not judge all Canadians by this one!!!

**FordMan77** · 11-20-2011

It's not a matter of holding up to the GT crank, its a matter of BALANCE. If the GT crank is not balanced to work w/ the GTP rod/piston combo then it will not work. IIRC the rod bearing (and possibly mains) are different in the GTP vs the GT motor, I would say no.

This is hurting my head. Since you say you are selling it, please do the potential buyer a favor and go get a COMPLETE LONGBLOCK from a good running motor, swap over your accessories, intake, etc. and call it done.

You will be doing this again when it grenades, which will be shortly. Why go through all the hassle of installing it just to blow it up again?? I don't understand the logic here. Either sell the car with a good motor or sell it as a rolling shell and move on. Nothing good will come of this.