302 vs 347?
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Junior User
Joined: Nov 2010
Posts: 82
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From: Rural Kansas
302 vs 347?
I'm really leaning towards dropping a small block into my 75 F250 that's getting converted to a regular cab swb, I've never owned a sbf in my life always FE or 385 series.
The truck is mostly just going to be a toy maybe drag around 1500lbs but rarely if ever.
I'm going to stick with a 4 speed, it was a 390 4 speed truck but the engine that came with it is beyond buildable to me.
I like rpms, I want to be able to spin it higher than 5500 and still have it making power. Bottom end torque isn't a huge deal with the standard but I need enough to get the somewhat heavy truck rolling.
I have found a couple of 5.0 HO roller motors I can get reasonable enough to start with but my biggest question is the 347 kit worth the money? Either way it will be getting a new rotating assembly but stock stroke is considerably cheaper.
If I go 347 it will have stock heads with just a valve job and springs put in compared to the money saved sticking to stock stroke would allow me to go with aluminum heads.
What do you recommend for the biggest power gains stroker or aluminum heads?
The truck is mostly just going to be a toy maybe drag around 1500lbs but rarely if ever.
I'm going to stick with a 4 speed, it was a 390 4 speed truck but the engine that came with it is beyond buildable to me.
I like rpms, I want to be able to spin it higher than 5500 and still have it making power. Bottom end torque isn't a huge deal with the standard but I need enough to get the somewhat heavy truck rolling.
I have found a couple of 5.0 HO roller motors I can get reasonable enough to start with but my biggest question is the 347 kit worth the money? Either way it will be getting a new rotating assembly but stock stroke is considerably cheaper.
If I go 347 it will have stock heads with just a valve job and springs put in compared to the money saved sticking to stock stroke would allow me to go with aluminum heads.
What do you recommend for the biggest power gains stroker or aluminum heads?
FTE Legend
Joined: Jun 2006
Posts: 31,930
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From: Ottawa, Ontario
Stock heads on a 5.0 make peak power at 5000rpm or less, on a 347 they will peak at 4000rpm, so to make a screamer you need better heads regardless. But building a reliable screamer is another thing, the 2-bolt mains on the stock 5.0 block are a known weak point and you will need to swap the stock hydraulic lifters for solids, and if you bump it up to 347 cubes you will need much better heads... like AFR 185s so this is not going to be a cheap build. IMO you would be much better off starting with a 351 and bolting aftermarket heads on it, leave the bottom end stock with upgraded pistons and forget about this screamer nonsense, build it to make peak power at 5500rpm or less.
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Junior User
Joined: Nov 2010
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From: Rural Kansas
I plan on putting a main girdle for a little extra insurance, when I say stock rotating assembly I meant stock stroke not factory parts.
The heads sound like a definite necessity either way, I've always had big slow revving motors and 5500 was pushing the upper limit on them with the standard backing it I am looking for a wider power range for each gear and would really like it to get there quick.
I can put 4.56 gears in the truck to get it moving I'm not concerned with highway manners so much.
The heads sound like a definite necessity either way, I've always had big slow revving motors and 5500 was pushing the upper limit on them with the standard backing it I am looking for a wider power range for each gear and would really like it to get there quick.
I can put 4.56 gears in the truck to get it moving I'm not concerned with highway manners so much.
Elder User
Joined: Nov 2009
Posts: 666
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From: Chicago area
A 351 with a properly set up bottom end will turn 6000 rpm safely. Do that and get better heads and you will be better off then a 347 based 302. The block won't crack and you can even stroke the 351!
A high revving 302 in a light Mustang is fun, but in a truck?
A high revving 302 in a light Mustang is fun, but in a truck?
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Junior User
Joined: Nov 2010
Posts: 82
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From: Rural Kansas
I'm pretty set on going the 351 route after some more research, I am thinking a decent built 351 will give me enough thrill to be happy and possibly in the future a stroker build for it.
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Junior User
Joined: Nov 2010
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From: Rural Kansas
I already have the bellhousing, it's not a big deal to build a set of towers for the stands and I don't have any exhaust or accessories or the mounting brackets for a 390. The block I have is junk and the crank is also. Where is the cost going to add up compared to trying to build and FE from what I have?
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Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
Ok, I was under the assumption your truck was complete. I've seen one guy spend a few grand converting an FE pickup to a small block. At a minimum, I'd build on a 94-97 roller 351W, not a 302 based engine.
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