ginnie's

so the cracked block in my daughters 3.1 was the back frost plug that's good news.
the bad new she melted one pistion......

Cylinder wall looks like it will be ok.



I had picked up a 2.8 that I was going to use, tested the compression had a couple of bad cylinders so I pulled the valve covers looks like the oil had never been changed.. good thing it was only $100.00

The 3.1 had dish pistions the 2.8 has flat tops



If the flat tops check out OK can I use them in the 3.1 I read these are non interference motors. Little more compression and save a couple of buck on parts the bore messures the same at this point guess wrist pin placement is the next question.

Six_Shooter

iTrader: (2)

You can only use the 2.8 pistons with the 2.8 crank, keeping it a 2.8. The writs pin height is different between the 2.8 pistons and the 3.1 pistons, to account for the difference in stroke.

To use the 2.8 pistons with the 3.1 crank, would cause the pistons to protrude from the bore at TDC. I don't recall exactly how much, since IIRC the 2.8 pistons are actually a few thousandths down in the bore at TDC. If I had to make an educated guess, the pistons would be close to .030 out of the bore. Even using FWD head gaskets this would put the quench height too close. Just as a compatison, the gen3 FWD engines have the piston proud of the deck height by .020", and use a .060" compressed gasket thickness leaving .040" quench height, about as close is as recommended.

project89

iTrader: (1)

u can use the 2.8 pistons with the 3.1 crank but they have to be fly cut.

i have a post here somewere were i cut apart the stock 2.8 pistons to mesure them and see how far u can safley fly cut them

in that post it also tells u what the cr would be with the cut pistions and each different head gasket

ginnie's

Ok does anyone have a stock 3.1 piston kicking around?

The piston protrude way more than whats going to work with the tools I have at my disposal

fasteddi

iTrader: (2)

i have some 3.1L pistons laying arround. What exact measurments do you need?

Six_Shooter

iTrader: (2)

I think he wants to buy some.

fasteddi

iTrader: (2)

oh ok. I have 5 good ones...

ginnie's

Standard Bore?
I was hoping for one my daughter is on a budget.........
a quick hone new rings and bearings its not a performance car for her the stock 3.1 is lots it just "pretty" her words not mine.

90 Fire engine red firebird with Ttops.

fasteddi

iTrader: (2)

I pmed you. Shipping is so exspencive to canada.

ginnie's

it lives! Thanks again Eddi!
It sounds good have a low idle and a bit of a stubble in gear at idle but other than that the daughter is pretty stoked!
TPS was showing .64 at idle warmed up, double checked the timing 10 degrees in D with the spark monitor unplgged, could not find any vacuum leaks with the stethoscope.
Oil pressure was rock solid, the IAC was at .43 at Idle, block learn was 121 but that should change after she drives it a bit no codes on the scan tool.
My only real problem was the EGR had to take the manifold in and have it drilled out and heli coiled........ oh yeah and the bracket the bolts to the air pump looked at it half a dozen time's could not remember what it was for the daughter figured it out!
Made her clean 90% of the matting surfaces for gaskets and help as much a she could she will appreciate it more with the new sense of ownership from getting dirt under her nail!!

project89

iTrader: (1)

the idle will clear up , search for 3.1 idle relearn , and u can get it done very fast, versues just driving it around and it taking a while

fasteddi

iTrader: (2)

No problem man, im glad the piston worked out well for you.

ginnie's

The idle has improve dramatically and the old 3.1 purrs now the daughter says it seems to have a bit more umph according to the butt dyno so she is pretty happy at the moment. It smells a little rich at idle I guess I will have to hook the scan tool back up and check things out. Is there a page that shows sensor operating parameters I can reference?

fasteddi

iTrader: (2)

What all parameters can you read out with your device? Im sure that me and others on here can tell you if your parameters are in order. I check the pages daily and so do others so we can help ya out. Im glad to hear that the engine is up and running good.