zerMATT951

So as you may have noticed in my other recent thread, I am likely in the market for a bottom-end swap. I was hoping that I could locate a low-mile motor locally, but the chances of that are slim, so here's my dilemma: Should I buy used engine parts (block, crank, rods, pistons) and put it together myself? I'm comfortable with the process of assembling everything, but I'm not sure whether or not I should first check main or rod bearing tolerances, install new rings (and properly gap them), etc.

So what do you think? Should I buy parts good used parts and assemble myself, or should I focus on finding a complete (assembled) donor short-block?

Clown

Matt if I could do it again, I would keep my eyes open for a 2.8 or 3.0L engine on ebay and just do a swap. Hopefully your engine is ok. Keep us posted when you get around to taking the head off.

Darwantae951

Your wording is kind of weird.

I don't know anyone who would assemble without checking tolerences.

Unless the same pistons were going in the same cylinders, new rings are probably the proper way to go.

If assembly is the way you end up going, do a lot of research.

zerMATT951

What else has to change if I went with more displacement? Intake manifold, head? Does the 2.5L exhaust manifold and crossover become restrictive?

Darwantae951

Head depends on the block used for the conversion. If a 3L was used, your 2.5 head will have to be modified. A 2.7 head will bolt directly on to a 3L block.

Intake would have to be port matched if you used a 2.7 head.

Stock headers and crossover are fine.

A 2.7/2.8/3.0/3.1 liter engine will bolt right in. Everything else depends on how much you want to spend (this coming from experience).

blown 944

I'll have something available really soon and all of your .2.5 parts will work. I'll be doing a few runs tomorrow night to confirm its capability at low boost levels. Keep an eye out for it.

Clown

Blown944 Tell us more....

blown 944

Just read the hybrid stroker thread. I'll be running it at the drag strip tomorrow to see how it does at 14 psi. The engine feels great far better than the 2.5. U have put over 1000 miles on it this week to get it ready to rock and roll

Tom M'Guinn

My view-- either buy a used healthy running motor (which is by far the easiest, lowest risk, cheapest, most 'rational' thing to do), or treat and assembly of parts as you would any rebuild regardless what the seller tells you....

Own Goal

^ agree, that is cheapest, easiest and quickest for sure. Knowing what you undertake and your cars....tear down your engine and do the rebuild yourself. Might be most major parts are reusable (crank, rods, pistons..might as well coat them). Then again, don't know till you get in there. Having seen your work I think you are way capable of building a first class engine.

2bridges

Every engine assembly you should at a minimum be double checking all clearances - even with all new parts.

Unless you want to throw together a temporary kind of engine
you definitely do not want to acquire random used parts and just assemble it.

used 20+ year old rods should definitely be checked/resized and new hardware
Used pistons are even more critical as a set.
Sets should be paired based on exact weights/ micrometer measurements, etc.

good luck

GARG

hey matt
i must have missed the other thread what happened you just got it together link to it
tks
gary

User 52121

Matt even if I were to buy a complete bottom end (even if "known good" from a reputable person like Lart) I'd still tear it down, inspect it, and freshen it up. If anything, just as a "while you're in there". New bearings, seals, etc. Cheap insurance. Just because the motor ran 100% fine before it came out of the donor car doesn't mean it's not on the verge of failure. It'd be no different than if you decided to pull and sell your bottom end 30 seconds before it locked up on you. It ran great right up until it didn't....

2bridges

Always fun to hear differing views.

I will say I would far prefer a known working functional used shortblock to a rookie disassembeld/freshened/reassembled engine.

Unless you have, or working with someone who has engine building experience there are way to many things to go wrong (reading clearances, using a quality torque wrench, parts prep, etc,etc,etc)

my 02 -

zerMATT951

This is all great advice guys - keep it coming . It sounds like no matter what I do, I'll be tearing into the replacement bottom end to refresh it, check tolerances, measure and weigh everything. Should I send individual parts out to be inspected (magnafluxed?) for defects first too? Are there potential defects other than grooves in the cylinders that I should be looking for too?

Gary, here's a link to the other thread:
http://https://rennlist.com/forums/9...pped-help.html