302 vs 351

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Nov 2, 2008 | 12:38 AM

smoke n tires

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From: midwest

302 vs 351

hey guys. i have a 302 in a mustang and i have a 1969 351w. id like to swap it but im worried i will have to sink a ton of money in it to get it going. will the early 26oz 302 balancer and flywheel work on the 351? how about the heads, they have stud mounted rockers, are they adjustable or just torque down? i want to keep this a mild street engine with a intake, headers, holley carb and a healthy cam. this will be on a 9.5-1 compression ratio and im going to spray my 125hp nos kit on it. what kind of power should i expect? this is how my 302 is built and it has in the 300-325hp range on motor. will the 351 give much more or is it not worth it?

Nov 2, 2008 | 09:39 AM

Conanski

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From: Ottawa, Ontario

You won't get any more HP from the 351 because the heads are no better, bolt on a set worthy of the displacement and you'll have 400hp on fuel alone.

Nov 2, 2008 | 10:03 AM

smoke n tires

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From: midwest

the 351 heads have 1.84 intake and 1.54 exhaust vs the 302s 1.78 and 1.48. ive considered bolting the 351 heads on the 302 but havent desided for sure yet. i dont like the rail style rockers on the 351 heads.

Nov 3, 2008 | 08:52 AM

Conanski

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From: Ottawa, Ontario

Still.. the ports on the early 351 heads aren't much different than any other windsor head, so unported they won't make much if any more power. The best flowing windsor heads ever produced are the recent GT40 castings, and even these are restrictive on a 351.

On top of that, because the 351 move so much more air it will peak much earlier.. about 1000rpm below where the 302 does, and with the additional low rpm TQ available you'll have new traction problems when launching. All that means your 1/4mi times and trap speeds will most likely suffer until you re-gear and learn to drive the car again.

Your heads likely have the pressed-in studs which aren't known for thier durability under heavy use, a common fix is to remove the studs and tap the holes for screw-in studs. All stud mount rockers require adjustment, only the pedistal rockers are set and forget.

I'm not trying to talk you out of installing the 351 though, it's a far more capable motor and even a mild build will make for an entertaining street ride.

Nov 27, 2008 | 11:31 PM

Decipha

Cross-Country

Joined: Jul 2007

Posts: 77

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From: New Orleans, LA

i have a 92 tbird with a 35w and 5spd... by far the best mod i've done to the car to date

swap the 351w and never look back

Nov 28, 2008 | 08:29 AM

53OlderThanMe

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From: Highland Village, TX

I just swapped my tired 302 for a rebuilt 351w long block last weekend. Here is a quick list of things I had to replace because they won't fit from the 302:

Intake
Distributor
v-Belts
oil pan (not sure if the 302 pan fits but I think I read it won't, didn't try as I had one from a 351w)

It fits great the block is 1.5 inches wider across the heads. Bolted right up to my AOD using the same 28 oz flywheel.

Jan 11, 2009 | 11:07 PM

jsutton

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Joined: Sep 2003

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From: Northeast LA

53olderthatme so all your brackets for accessories bolted up to the 351w, you just needed longer belts? I was talking with my wife today about a new project and of course she told me I already had one. I said I'm running out of things to do it. Then I said, except for build bigger engine. She said yes. So I'm thinking about, within the next few months working on a 351w to put in my truck to replace the 302. I already have a duraspark II distributor for it so ignition won't be a problem. I should have put a new cam in my 302 when I redid it, but I didn't. So, I will put a bigger cam in the 351 if/when I do it and I'll be using my carb and hopefully since my exhaust is very short (dumps right behind the cab) I can reuse that stuff by just repositioning it.

So the main question I have is will there be a noticable seat of the pants difference in moving from a pretty stock 302 to a 351 with cam in it. I would guess yes but I just wonder if it's worth it. I don't tow anything or haul anything it's just my fun project.

Thanks,