First time putting a motor together and I have a bunch of stupid questions

The motor in question is a 2.4 turbo out of a 2005ish PT Cruiser. Technically it is a "turbo lite" but casting number and part number wise it is the same as an SRT-4 or PT GT. The motor was pulled from a junkyard car and I disassembled it and sent the head, block, bedplate, and crank to the machine shop to be checked out and cleaned up. When I picked it up on Friday, they told me they did a line hone, cylinder hone, replaced the guides and seals, and decked it .005. I'm getting my rock auto order together so I can start putting it back together per the FSM and I've got plenty of ignorance to work against here. I'm going to order up the gasket/seal set, new tty head bolts, new tty rod bolts, new rings, new oil pump, new water pump, new timing parts, new balance shaft guides, and new bearings. Since nothing needed to be bored out, I know that I just need standard size things but I'm not sure what I need to do about the bearings.

The bearing clearances are in the FSM, so I've got that but how do I determine what size bearing I need? Do I use the old bearings and plastigage? Do I buy new standard size bearings and try to return them if they don't measure the proper clearance? What about the rod bearings - do I use the old TTY bolts to check clearances or an I supposed to buy two new sets of expensive bolts? Is it necessary if they didn't need to grind on anything?

I know this is probably a majorly n00b set of questions but the rest of the internet seemed pretty vague and contradictory. This isn't for a challenge budget so I'm willing to spend the money if it's necessary, but balance that against trying to keep it to a reasonable budget. This is a stock rebuild that will go in to my rallycross car and see relatively stock boost levels.

Fair warning, this is probably the first in a series of stupid questions that I'm going to come up with!

Not a total noob question, as I don't know the answer either. So don't feel bad.

I just did a crank replacement in a 2.4 (not my first one, either - thrust bearing failure rate is high) so the engine is fresh in my mind.

Plastigaging the main bearings would be a good idea if they line honed the block just to double check their work. I wouldn't worry about checking the rod bearings given the crank and rods are standard, but if you do it, use the old bolts.

If you got OE type rings, they are almost certainly pre gapped. Measure a few to be sure, all of them if you're anal-retentive, but you'll probably find them to be at the high end of spec. Given that you're going to be throwing boost at it and you're going to be running everything HOT for 40-70 seconds with minimal cooldown, I'd run everything toward the looser end of tolerance. A tiny bit of lost compression is way better than butted rings. Plus you need to future-proof against the more power that you're going to tell yourself that you want someday

And oh yeah, make sure that your bearing kit came with TWO thrust bearings, not just one like Chrysler put in the engine originally. The bedplate is machined for it, they just cheaped out in production. Which is rather why every now and then I get to tear the bottom end of a 2.4 apart.

Its been a while since I've had an engine apart to the point of doing rod and main bearings

I could swear in the last one I had apart (gm) the bearings are marked on the back side of the shells with the size.

If they are marked it will give you a starting point, but the new ones should still be checked for proper clearance.

Machine shop should have told you if you needed "+10" bearings or whatever if you needed them. My guess is you don't (mains and rods).

You should also be able to check with digital calipers.

Here's what I learned in my first engine rebuild: don't skip the loctite.

On some of the more popular motors reusable head studs are close enough in price to the tty OEM replacements that it's the way to go, particularly with boost in the equation.

I too would look into reusable bolts. Hopefully you'll never need to get into the engine again, but you never know. OEM bolts are overpriced in my opinion.

Look at crank and see if a number has been stamped in it. Usally on first throw.

Awesome, thank you all for the learning'!

I need to double check, but I'm pretty sure I had specced the reusable head bolts and rod bolts - although the only place in the world that has arp rod bolts is modern performance which I find kind of weird.

When I picked up the engine I did specifically ask if I needed oversized or undersized bearings and they said that it was all standard and they just gave it a hone, so I take it the clearance checking should be more of a sanity check to just make sure.

There is a difference between honing the cylinders for new rings and a line hone, which is a different process entirely on the main saddles and is exactly what it sounds like.

I'm not sure that this engine could be line honed easily. Normally you cut a small amount of material off of the mating face of the main caps so that after you line hone the mains, they are at a standard ID. The problem with that is the bedplate would be a pretty significant machining operation. And one of the bellhousing dowels is in it, which could make things interesting. And the crank sensor is mounted through the parting line, so it might have to be rebored.

If they didn't do any of that, the mains ID is oversize, so you should probably check the mains clearances to be sure.

Don't forget the assembly lube!

I don't know it's necessary (or goes without saying) but I wore latex gloves while handling parts. Cleanliness is your friend!

Don't forget the lube. Always good advice!

I've just submitted my rock auto order. Machinist told me that I should order standard size mains and plastigage them to verify, so we'll give that a try. I've got to get my con rod bolts and various mopar gasket maker chemicals yet, but I guess it's time to build-thread this thing. Here goes nothing!

Okay, next dumb question:

Right at the top edge of two of the pistons, there's a teeny little nick (more scratch-like than giant divot) that starts on the top surface and then goes down about a third of the way to the topmost ring land. Am I correct in assuming that I can get a little fine emory cloth and take the rise out of that and be okay? I know that I don't want to have anything that can scratch the bore, but a tiny nick won't affect sealing since that's the job of the rings, right?

wae wrote: Okay, next dumb question: Right at the top edge of two of the pistons, there's a teeny little nick (more scratch-like than giant divot) that starts on the top surface and then goes down about a third of the way to the topmost ring land. Am I correct in assuming that I can get a little fine emory cloth and take the rise out of that and be okay? I know that I don't want to have anything that can scratch the bore, but a tiny nick won't affect sealing since that's the job of the rings, right?

You are correct. The rings do the sealing. Light polishing with the emory cloth is ok.

And clean off all debris left over from smoothing that down. The abrasive grit will have a field day with the rings and cylinder walls.

I was figuring a final dip in the can of Berrymans with a rinse and a blow dry would get rid of any leftover grit or metal bits.

Scrub with a brush. You have kids, they have toothbrushes, borrow one of them.