This is topic rod piston question. in forum Tech Talk at Northern California Ford Owners  .


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Posted by Pure Stang (Member # 7251) on :
 
trying to learn a little something. can you just install a 5.400 (i think need to double check) rod and a 30 over bore piston to a stock block just boring the block? or does crank need to be changed? what is stock length? if it works with a stock crank what will be the ci? thanks peeps
 
Posted by wilit (Member # 3367) on :
 
5.090" is the stock 302 rod length. Boring the block will not affect anything with the rod length/ratio. The 289 used a 5.155" rod and most stroker kits use a 5.400" rod, though some Probe kits use a 5.315" rod to move the ring lands up out of the wrist pin area.

If you're using a stock 302 crank, you need a 5.090" rod. Boring the block .030 over will get you 306 cubic inches with a stock 302 crank.

[ May 26, 2011, 01:08 AM: Message edited by: wilit ]
 
Posted by Pure Stang (Member # 7251) on :
 
Cool thanks.
 
Posted by 93PONY (Member # 60) on :
 
You can get .030" overbore pistons for a 5.400" rod and 3" crank. It's what they call a long rod 306.

The longer the rod, the shorter the compression height of the piston in order to run in the same deck height.
Compression height = distance from wrist pin to top of piston.

Deck height = 1/2 stroke + rod length + compression height
IE 8.2" = 1.5 + 5.09 + compression height
or
8.2" = 1.5 + 5.4 + compression height

Work the formula for compression height and find pistons with the correct bore and compression height. Hint: Probe makes them.
Remember to check the rod specs as well. .927" pin bore in the piston will not work with a rod that has a .912" pin bore. Same goes for the big end. Some 5.4" rods are setup for a SBC rod journal size instead of a Ford journal size. The crankshaft can always be ground down to SBC size....and you can off-set grind the crank for more stroke.
That's how I got a 3.10" stroke out of a stock 5.0 crankshaft. I had the journals ground down to SBC size (2.0") and offset to increase the stroke. 5.4" rods and custom pistons (using formula above to figure out compression height) and I had a mild Stroker. You can also offset grind for less stroke, or go down to a Honda Journal size!

[ May 26, 2011, 10:50 AM: Message edited by: 93PONY ]
 
Posted by turbo50 (Member # 6700) on :
 
Shaun is correct, however, he either does, owns or knows someone with a machine shop lol

That stuff adds up at a machine shop, as do the pistons.

I think you could stroker kit it and call it real if you dont already have ur parts.
 
Posted by Pure Stang (Member # 7251) on :
 
I have the pistons and rods. Had them in my garage already. Just spare parts just trying to figure out what to do with them. Forged pistons and h beam rods.
 
Posted by triple b (Member # 8763) on :
 
I cant remember where i saw it but if google long rod 306 you can find the piston you need to make that work. I think its a chevy 327 piston not 100% sure tho.
 




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