Messed up stroker, WWYD?

[Dagamus(NM)]

So over the past few years I have been rebuilding a stroker that I bought second hand. The engine was sold to me as a 2.7L several years back from a fella in Chicago. He said it was built by some shop in California in conjunction with Ireland Engineering etc etc and it had about 20 hours of race time on it.

Well it turned out to have so much blow by that I could hold my hand to the tail pipe and it would get covered with little black speckles. It had custom pistons and a forged turbo diesel crank so I decided to get it rebuilt.

I had to have a few foot surgeries and recover from them so the engine sat at the machine shop for quite some time. While I was rather medicated I made the decision to swap to s50 rods as I had done with my other stroker. I did not stop and think that the rods in the block were 130mm eta rods rather than 135mm 2.5i.

Well, the machine shop simply followed my instructions so I am left with pistons that will likely poke +5mm too far out of the block.

Options are to:

1) buy new pistons designed to work with this setup. Would need to have rings filed and check wrist pins against small end of rods. (Already have rings matched to this block with current pistons)

2) go to 2.5i crank (need to pay for all of the machining to match crank to block, rods, already have this done for the TD crank and this block)

3) go back to the eta rods (rod to stroke ratio decreases, might have been part of why rings were tossed) simply have them matched to the crank and hang the pistons on the rods

I have another block, the rotating assembly from both an seta and 2.5i. I could save the s50 rods for that block and hang them on the 2.5i crank with stock pistons or get custom pistons made to put on them.

Pretty sure 3 makes the most sense. Already had the bearings coated and don't really have the money at the moment for the other options. Not optimal, but at least I only have to pay for the rods to be conditioned, sized etc. and the pistons placed onto them.

[djjerme]

What are you intending to do with the motor? Is it a track car, daily driver..etc?

I'd say get the right rods since those can be found fairly easily and cheaply. Eta rods aren't terrible and are fine in race motors (friends eta has several completed 25 hours of Thunderhill on it.)

[Dagamus(NM)]

I still have the eta rods. They are in great shape, honestly cannot believe that I messed that up. I guess dilaudid will do that though.

This is a turbo'd weekend car. Live in the garage doing nothing most of the time.

[SkiFree]

ETA rods, new rings (will need piston job number [on the underside of the piston crown]). Have machine shop check piston/bore clearances, hone, etc. If the bores are gouged/worn, your issue will happen again.

The IE forged pistons require a fair amount of piston to bore gap. If the car was not allowed to warm up before romping on it, that would cause a lot of blow-by and ring wear in short order.

In regards to your #1 option, try not to ever have forged pistons made to fit a given hole. It should always be vice-versa.

[rturbo 930]

In regards to your #1 option, try not to ever have forged pistons made to fit a given hole. It should always be vice-versa.

I'm curious, why is that?

[Dagamus(NM)]

ETA rods, new rings (will need piston job number [on the underside of the piston crown]). Have machine shop check piston/bore clearances, hone, etc. If the bores are gouged/worn, your issue will happen again.

The IE forged pistons require a fair amount of piston to bore gap. If the car was not allowed to warm up before romping on it, that would cause a lot of blow-by and ring wear in short order.

In regards to your #1 option, try not to ever have forged pistons made to fit a given hole. It should always be vice-versa.

The pistons are made by JE but apparently before they laser etched the job number on the bottom. The pistons are 85mm and that is all they say on the bottom. KH appears to be 34.2mm but I am not using a very precise measurement method. The crown matches that of an i piston.

The benefit to getting new pistons would be having deep valve reliefs cut into them. Not sure how deep they need to be for non-interference though and if using a 135mm rod then how thick can the crown be if I am already pushing the center of the wrist pin up 5mm from where it is now.

The block was bored out by the previous owner, my machine shop said everything looks very close to exact spec. The rings are all fit to the individual bores. Piston crowns have the moly coating on them.

I have a long list of everything that they did to the block, crank, rods, etc. but yeah, the block was hot tanked, decked, honed. Crank was polished, rods had new bronze bushings installed and the big end sized with coated bearings.

My other stroker has the Ross I.E. spec pistons in it and those are sloppy when cold with quite a bit of expansion in them.

Well, it seems that the eta rods are going back in. Going to take them back over to the machine shop now. I needed to drop off a head anyhow.

[SkiFree]

I'm curious, why is that?

Much less chance of error. If an individual specs the bore size for pistons (not the machinist), the chance of problems are much greater. You don't read about it much given the personal embarrassment.

The pistons are made by JE but apparently before they laser etched the job number on the bottom. The pistons are 85mm and that is all they say on the bottom. KH appears to be 34.2mm but I am not using a very precise measurement method. The crown matches that of an i piston.

The benefit to getting new pistons would be having deep valve reliefs cut into them. Not sure how deep they need to be for non-interference though and if using a 135mm rod then how thick can the crown be if I am already pushing the center of the wrist pin up 5mm from where it is now.

The block was bored out by the previous owner, my machine shop said everything looks very close to exact spec. The rings are all fit to the individual bores. Piston crowns have the moly coating on them.

I have a long list of everything that they did to the block, crank, rods, etc. but yeah, the block was hot tanked, decked, honed. Crank was polished, rods had new bronze bushings installed and the big end sized with coated bearings.

My other stroker has the Ross I.E. spec pistons in it and those are sloppy when cold with quite a bit of expansion in them.

Well, it seems that the eta rods are going back in. Going to take them back over to the machine shop now. I needed to drop off a head anyhow.

If we are talking IE/JE pistons on this stroker, then they are at least 8-10 years old! As long as your machine shop says the piston/bore still check out, then great.

You have brought up the issue with doing a non-interference piston and it's affect on the rings/wrist pin. It introduces more issues while it only solves an issue easily avoided by decent maintenance.

[Dagamus(NM)]

Much less chance of error. If an individual specs the bore size for pistons (not the machinist), the chance of problems are much greater. You don't read about it much given the personal embarrassment.




If we are talking IE/JE pistons on this stroker, then they are at least 8-10 years old! As long as your machine shop says the piston/bore still check out, then great.

You have brought up the issue with doing a non-interference piston and it's affect on the rings/wrist pin. It introduces more issues while it only solves an issue easily avoided by decent maintenance.

The block was at the machine shop the past four years. 18 months x2 for surgeries put everything way behind. It was at least two years from when I got it to when I tore it down so yeah, old JE pistons. The Ross pistons I got from IE in 2003.

If I was to have pistons made with 130mm rods I would think it would be fine for cutting deep valve pockets. Once the wrist pin gets pushed up for a stroker it becomes an issue as the rings are pushed towards the crown.

Well the head was dropped off to get disassembled and inspected. See if the valve guides need replacing. I'll get the cam measured as I cannot recall the specs. They were lost along with the e30tech database. 272/272 maybe, 11.4mm lift is what comes to mind but who knows. I know the other has a 288/288.

I need to get the block up on the stand while I wait and paint it. I let my son pick out the color for the block. He chose Chrysler red. He is four so I rolled with it.

[digger]

if you have s50 rods why would you order pistons to suit 130mm rods?,

metric mechanic manage to fit non interference pistons with 135mm rods and 89.6 stroke which has 24-25mm compression height, not that making the valve reliefs that deep is a good idea in the first place

[Dagamus(NM)]

if you have s50 rods why would you order pistons to suit 130mm rods?,

metric mechanic manage to fit non interference pistons with 135mm rods and 89.6 stroke which has 24-25mm compression height, not that making the valve reliefs that deep is a good idea in the first place

Separate thoughts. I wouldn't get 130mm pistons for s50 rods.

I am not sure how deep the reliefs would have to be cut to make an m20 non-interference. Seems like it would be a fair amount. Could get creative with the dome of the piston to maintain compression. I am curious to see what metric mechanic non interference pistons look like.

Separate thought. What kind of bolts do you use to secure your block to your engine stand?

[digger]

Separate thoughts. I wouldn't get 130mm pistons for s50 rods.

Obviously lol, I mean you have both eta rods and s50 rods why not use the better rod and get a piston for them (if you need pistons)

Separate thoughts. I wouldn't get 130mm pistons for s50 rods.
I am not sure how deep the reliefs would have to be cut to make an m20 non-interference. Seems like it would be a fair amount. Could get creative with the dome of the piston to maintain compression. I am curious to see what metric mechanic non interference pistons look like.

It depends on the cam, for example with schrick 288 the difference between what you need for inference and non interference would be approx. ~9mm.
You can indeed adjust the dome to compensate for compression but you will still have have the pockets where the flame front wont reach and thus wont burn properly.

[Dagamus(NM)]

Obviously lol, I mean you have both eta rods and s50 rods why not use the better rod and get a piston for them (if you need pistons)

This is my dilemma. Cost and time at the moment. It would just be more work as the pistons have to be removed and the new ones installed (well, this is the same for swapping back to the eta rods) but then have to have the rings measured, filed, and the block possibly reworked for the new pistons.

Also probably not a big deal but it will be at least 1k for the pistons. plus the extra work. Then what? I could sell the pistons to somebody here I suppose. The rings would probably be trash though. Maybe not if the buyer's block had to be bored anyhow.

I suppose I would stick with JE pistons. Racetep and VAC both have the dimensions needed for the pistons.

Then the add ons. How many options should I choose for a street boosted engine. Coatings, grooves, etc. etc....

[digger]

if you can salvage the pistons then do so, be sure to check that they are truly salvageable including ring grooves and ring axial clearance. the forged pistons that you'd have are not known for longevity like an OE pistons is

[Dagamus(NM)]

if you can salvage the pistons then do so, be sure to check that they are truly salvageable including ring grooves and ring axial clearance. the forged pistons that you'd have are not known for longevity like an OE pistons is

I trust my machinist. I asked specifically about these. He said everything spec'd out.

I do think that these have little run time.

That said, if I can sell a few computer parts I will pick up a set of pistons.

[digger]

then there probably isn't much point running getting new pistons