Engine Displacement

TruRooster

Member
Aug 22, 2016
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Hey Everyone

Y'all know what a safe displacement would be for a 302 5.0 would be when boring out the cylinders? I see a lot going 30 over but would it be possible to safely go over that?

Thanks
 
The castings for 5.0 blocks are the thin wall type, and don't have a lot of extra meat for an overbore. Somewhere in the range of .030 to .040 is the max safe range without having the block checked for casting shift. This is a specialized process using a sonic device that has been around for some time.

If you want more cubic inches, a 3.25 stroker crank drops right in without having to clearance the block for the rod bolts.
 
347 stroker

That isn't exactly a drop in replacement; there is some grinding that need to be done to get the rod bolts to clear the bottom of the cylinder bores. You end up installing one piston and rod assembly minus the rings 8 times. That does not include the laborious effort to remove every speck of filings and grit every time you check a rod and piston assembly for clearance. You have to grind the bottom of the cylinder bores; you absolutely cannot grind on the rod bolt heads and expect the engine to hold together at high RPM.
Remember that these are thin wall castings: if you grind too much material, you will either end up with a hole that goes into the water jacket or a crack that starts traveling somewhere else.
 
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If you're going to go through the trouble of boring, then you may as well pony up a little extra cash for a stroker kit. You'll have to buy new Pistons either way....what's another few hundred bucks for better rods and crank while you're at it. You can stroke that engine for about $1,000. Decent Pistons will easily eat up $300-$400 of that.
 
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My 347 short block was just over $2,000 all in. Scat crank, probe pistons, probe ultralight I beams, arp rod bolts & main cap studs ect..
How long ago was that? The price of almost everything goes up every month.
The only that that has gotten less expensive over the last year is the cost of a gallon of gas...
 
I bought my CHP rotating assembly for $880US about 4-years ago (balance included). Depending how you get it balanced, you may need to buy a new dampener and flywheel (if you go with the 28oz or zero balance option vs the standard 50oz.)

I think the same kit is about $250 more now?