Driv200

iTrader: (1)

Just measured the cylinders on my 2.4. Is there room to do a re-build or not?

Cylinder 1 - 3.426
Cylinder 2 - 3.423
Cylinder 3 - 3.423
Cylinder 4 - 3.430

Can you use a 87mm bore for a rebuild? Or, would you source a new block and start over again? Pistons, rods, and everything are fine with 5000 miles which I might be able to reuse on a new 4g64 block.

Dallas J

iTrader: (1)

I think youre still fine if you add in your PTW clearance, but certainly need to have the shop measure things. Like check for out of round or taper to see if those numbers are worse in places.

LetsGetThisDone

iTrader: (1)

3.430 is already 87.122mm, block will need to go to 87.25 or 87.5.

Driv200

iTrader: (1)

Really?

I thought it was out of spec and to thin at 87.5. I sourced a 4g64 and will be starting with it hoping I might be able to re-use my current pistons/rods. If not, I might turn my current block into a larger monster. Does anyone sleeve cylinders for road race? Or is this to expensive?

Dallas J

iTrader: (1)

87.5 is pretty much the limit, thats a 4g64 bored over .040 or a 63 gone 80 over. You really would have no room left to hone or repair if something happened. Good thing is, when we trash a block usually we do it in a way that honing is a cure

Dallas J

iTrader: (1)

One thing I'm not sure of is when a piston says 87mm bore, are they themselves undersized by the PTW clearance or are the pistons right at 87mm (+/- tol.)?

kikiturbo

pistons are always specced to bore size.. i.e. they are undersized for PTW clearence..

as for the OP question... torque the head back on and measure real bore size and ovality.. then decide.. but from the looks of it it needs a rebore..

LetsGetThisDone

iTrader: (1)

The "size" of the piston is bore size, the piston itself is "undersized" for PTW clearance.

Dallas J

iTrader: (1)

Thats what I thought, just never actually measured my own new pistons on any of my motor builds.

So when you buy a piston for a 87mm bore, you really are going to bore over 87mm if you subscribe to more PTW is better on a 4G. I run about 0.0045 instead of the 0.0035 the pistons recommend.

LetsGetThisDone

iTrader: (1)

Yeah, bore size listed would be for intended PTW. This is why pistons should always be measured, and then the cylinder gets bored/honed to the appropriate size for PTW.


And, yeah, depending on intended power output, .0035" is not enough lol

Driv200

iTrader: (1)

I am learning so much and enjoying this project.

As I thought, I could re-use my current block at 87.5, but would have to also buy all new pistons etc. Always on a budget, I bought a $300 4G64 block and hope my pistons and everything are able to be reused, which would save me a lot of money. If I can't reuse my internals, then I'm starting a go-fund me account here on EVOm! 😀 And then I will have two 4G64 blocks to rebuild. Ha!!

LetsGetThisDone

iTrader: (1)

You need to buy rings and pin locks for your current pistons, so with that plus the cost of the block, you could have almost gotten new pistons...lol. ExtremePSI sells Wiseco HD's for like $530...

Driv200

iTrader: (1)

That's a good point. I might go this route and sell the new block...or keep it for next rebuild. Appreciate the tip and where to buy new pistons.

Driv200

iTrader: (1)

With the new block and cradle, is there an alignment process to install and use my ARP bolts? Does a machine shop need about $800 for this? I thought it all dropped in since it came together originally. Are my ARP bolts different?

LetsGetThisDone

iTrader: (1)

I've built a few 4g63's, none of them have needed align honed with ARP main studs. They seem to stay straight/round without issue. I think its because of the girdle. Also, an align hone should not cost $800. My last machine shop bill was $875 for: hone .010", remove core and galley plugs (head and block), deck block, deck head, valve job, hot tank block and head, install new core and galley plugs (head and block), balance crankshaft and flywheel, replace and hone for pin fitment small end rod bushings, check main bore alignment, sizes and roundness, check rods for length and big end bore size/roundness.