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Advice on a new rotating assembly.

2K views 1 reply 2 participants last post by  smashedheadcat 
#1 ·
Hi everyone. Hope your day is going well:)

I bought a Mach 1 back in Aug 2017 knowing that the engine was going to require a rebuild. I got it for a great deal!

I finally removed the engine from the car over Christmas break and started the tear down right away. First thing I found was lots of metal in the bottom of the pan. Every thing looked good on the initial visual inspection(of course). I removed the #1 piston and rod and seen a little metal coming out from the #5 rod bearing. As I pulled on the #5 rod it basically flopped around on the crank. Upon further inspection there was not a whole lot left of the bearing. I continued tearing the rest of the engine down and found no other issues. All the rod journals measured 2.086 except #5 that measured 2.059. I measured all the bores and they are all within .005 of 3.552"

So now I am on the hunt for a new rotating assy. I don't intend to add forced induction as I would like to stick to N/A. In a perfect world I would like to hit 350-400 RWHP which I know is a long shot stock with bolt-ons. I'm not afraid to spend money so I am looking for advice on a new rotating assy. Crank, rods, pistons, bearings and such. Piece it together? Is there any kits you would recommend? Any info would be great and if there is any info you need from me just ask.:)

Thanks
Jamie

P.S. I'll post pics when I can.
 
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#2 ·
There are tons of ways to go with this, and with your power goals, you can use almost anything. With no plans for forced induction, I would probably go this route:

OEM Block: I think you'll get a few ponies by boring it out. Typically, I do not recommend this as it weakens the block, but in an N/A application, you'll be well within the fail point of the cylinder walls/headgasket sealing.

Crankshaft: If yours is toast, you can pretty much go anyway you want here. You could even use a cast crankshaft as it would hold up to your power goals (and may even cut a bit of rotational weight).

Connecting rods: If it were me, I'd save a few bucks and grab a set of Boss 302 rods. These have proven to pretty badass and the price is tough to beat.

Pistons: I would bump up the compression, but pick your poison. I'd say a set of flat-tops would be the absolute minimum I'd go for. If you want 350-450rwhp, you'll want to get a bit more aggressive here. I will be the first to admit that I am not the best person to recommend a piston (especially for an N/A variant), so you're going to want to speak with some experts. I'd first look for someone who has done what you're looking to do and ask for some assistance.

Bearings: King SI. Have a look at Ed's post. He explains it much better than I ever could: Click Here

The end state:

To be honest, I don't think you'd have much trouble getting to 350 hp with a compression bump, just make the intake and exhaust are opened up. To get in the 400+range, you're going to need to address about everything. In any build, you should look at what you have and compare it to what your intended use and goals are. If the parts you've got don't match what you want to do, you'll have to change the parts or change your goals. For example, if you want an 8000+rpm monster, the stock intake and cams are not going to do you any favors. It really doesn't matter what the rest of the engine is filled with, you have to address the ineffeciencies.
 
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