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Hi All,
I have some questions for anyone that uses N20. I am going to put it on my bogus Boss 302 and am wondering about a few things. how well will it work if I don't have headers, just manifolds. How much can I put to the motor safely it has 289 rods polished and shot peened with good bolts. forged boss 302 pistons, and stock cast 302 crank. 2 bolt block, 2v cleveland heads and dual plane manifold. 750 DB carb, C4 trans built 3800-4200 stall convertor. This is all in a 72 Maverick with 2 1/2" exhaust. The same motor ran 12.65 in my Pinto with manifolds and 3" straight pipes so it is no slug, but not a rocket ship either. Thanks for any thoughts you may have.
 

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I estimate that your engine could easily hold a 150 shot. Because you have forged pistons, you are in good shape! There are alot of guys putting even more to their late model 5.0's with stock bottom ends, and yours is a little beefier than that!
Just keep an eye on your head gaskets....but start off small, like a 75 shot, then work/tune your way up to a higher HP level.
 

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289 rods on a 302 piston, and 302 crank? can you do this with any 302 piston or just the boss? And because of the longer rod, does it give you a couple of more Cubes? Sounds like something i will do in my 302 im about to rebuild then.
 

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You get cubes from the crank. Longer rods just improve the rod to stroke ratio. It is supposed to make the crank throw a little better due to the longer rods leverage. I checked mine at one time and I believe you can shave down the tops of 10:1 hipo 289 TRW pistons to work with a 302 crank/289 rod setup. Its still a 302 but just with a 1.71 rod ratio instead of the stock 1.69. I never set one up and checked it but I seem to recall the cut would be around .020 to still leave a little below the deck. I was told the hipo pistons would shave down that much with no problem since they are forged. I'm not sure how hard the balance would be. You'd have to recheck your valve clearances of course.
 

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Had a 302 set up with 289 rods and the pistons were above the deck. Pistons were VERY close. The head gasket took up the difference and that was all.
 

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I used 289 rods in a 302, and the pistons were right at 0 deck. The pistons were speed-pro cast flat tops, the block was a "tall-deck" (8.236&quot
302. The '73-'76 blocks had a hair taller deck which makes it easier to make the 289 rod swap. Not much power difference, though, and you MUST balance the entire assembly.
 
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