347
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From: Mt. View Hawaii
347
I am thinking of using the 302, instead of the 351 ,I have and stroking it to 347 then putting the 69 351 heads on it. What kind of power could I get? Thats also with the 4 barrel carb and intake and cam. Going for the torque side so I would use a cam for torque.
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From: fargo, nd
you wouldnt be able to use those pistons unless you went to race gas- an 11cc dome would put your compression about 12-1. you have the idea though- more displacement=more torque. it would be cheaper though to just get a 351w and rebuild that, unless you had a space-limited application like mine (1975 ford maverick). the 347 would come out about the same as the 351w as far as power goes, also youd have to get the short rod 347 if you dont want it to burn oil- thats whats going into my maverick- a short rod forged assembly- 1600 dollars balanced and shipped
Last edited by darrin1999; Jun 18, 2007 at 02:41 AM.
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From: Mt. View Hawaii
Well I've got the 302 and am going to get the 351 soon and was going to stroke the 351 to a 393 but I only have the stock heads for on it so I thought of running 302 and stroking it to a 347 and then put the 351 heads on it and I would have the bigger valves and ports of the 351 on the 347. That and I would think I would get better fuel mileage from a 347 rather than a 393.
I was told the 351 I'm getting dosen't have a crank, con rods, or pistons so that is why I was going to do the 393.
I was told the 351 I'm getting dosen't have a crank, con rods, or pistons so that is why I was going to do the 393.
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From: fargo, nd
another thing to note- if youre trying to make big horsepower then you dont want the 302 block- they have a tendency to break in half once you pass the 450 horse mark, the 351w blocks are good to 550
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From: Mt. View Hawaii
Well I'm trying to decide between a 351 stroked to a 393 running stock heads or a 302 stroked to a 347 running the 351 heads. Which would be the better of the 2? It's for my truck, I don't think on my budget it will reach the 400 hp mark but which would be the better build?
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From: fargo, nd
351w would be a much better start... itll get the same mileage and be able to put out more power for less money because you dont have to revv it as high. 400 horse would be pretty easy with a 393 or 408 stroker- both will fit in the 351w stock block. if you get a 351w block, get one from 1994 or later- theyve got hydraulic roller cams which will reduce friction and increase power and mileage- and another bonus is you dont have to worry about cam break-in, which is a big killer of fresh rebuilds in recent years because the newer oils dont have the zinc to protect the cam, so they wipe pretty easily.
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From: fargo, nd
i didnt have a choice on my maverick- all thatll fit in there without modifications is the 302 block- but if id had a choice i would have jumped on a 351w 
or if i had a bit more money and some welding skills, i would have put a big block in it 
or if i had a bit more money and some welding skills, i would have put a big block in it
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From: Ottawa, Ontario
A 347 built from a 302 or a 351 as is should produce nearly identical TQ/HP curves, if the same induction, cam and exhaust are used on both motors. The 351 will be the cheaper build of course because it's doesn't need a stroker assembly to get to 3.5" stroke. Any of the factory heads will limit peak HP to somewhere around the 300hp range though, and a bigger motor will obviously get there at a lower rpm. A modern 351 block with the '69 351 heads on it would be a good all around low $$ combo for the OP which should produce good power.
A couple more points about the 302 block versus the 351. The 302 block is well suited for a naturally aspirated 347 stroker motor built to rev(7500rpm territory). The smaller diameter main journals work in your favor here, less friction raises the potential rpm ceiling compared to the 351 block. The 302 block will handle up to 400-500hp, with flexing resulting in blown head gaskets the biggest problem at those levels. Typically a blower and/or nitros is need to get this kind of power though. The larger journals in the 351 are better suited to low rpm power production(under 5000rpm), more surface area will handle higher loads better(think higher compression and displacement), and should last longer.
A couple more points about the 302 block versus the 351. The 302 block is well suited for a naturally aspirated 347 stroker motor built to rev(7500rpm territory). The smaller diameter main journals work in your favor here, less friction raises the potential rpm ceiling compared to the 351 block. The 302 block will handle up to 400-500hp, with flexing resulting in blown head gaskets the biggest problem at those levels. Typically a blower and/or nitros is need to get this kind of power though. The larger journals in the 351 are better suited to low rpm power production(under 5000rpm), more surface area will handle higher loads better(think higher compression and displacement), and should last longer.
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From: Mt. View Hawaii
I'm not trying to get any specific stroke length or anything I'm trying to decide between the 347 and 393. Either motor would need the stroker kit, as I said above the 351 has no crank, pistons, or con rods. But my concern was that the 351 heads might not flow good enough even with the port and polish, no valve resizing, to expensive, and no aftermarket heads either. I thought as far as the 351 heads go they would work better on the 347. But from my readings in books and stuff I heard that say for example putting the 351 heads on a 393 might help it with torque and you only want super high flowing heads for high rpm. I have never gone above 5000 rpm and, that was only to get up to speed because of gearing issuses, don't ever intend to. I live in Hawaii and have very very limited resources like junkyards and machince shops and want shops and stuff are here are very expensive. I can't even find a tailgate for my truck!
Aboslutely not even thinking about boost or nitrous oxide.
Aboslutely not even thinking about boost or nitrous oxide.
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From: fargo, nd
yep... for a limited rpm motor youll be much happier with the 351 stroked to 393. the 347 would have to revv much higher to make the same power, and wouldnt have as much low end torque- which is what you want.