302 to 347 upgrade

[ryanrock69]

Good day,
I searched the forum and didn't see anything on the 302 to 347 upgrade. I have a few questions.

Has anyone done this and if so what are your thoughts?
I want to build the engine before swapping for current 302. Will any 302 block work or do I need to find a specific one?
Will the new block slide into the existing motor mounts, etc or are there under hood modifications?
Any gotcha's I should look out for before starting?

As you can probably tell I'm brand new to this. I did a 352 to 390 swap 30+ years ago with my father but he's not around this time.
I've watched several youtube videos on the process and feel like I have decent handle on the process but it's the parts gathering I'm confused on.
Thanks.

 

[Timmy390]

Nice read.... https://www.motortrend.com/how-to/ccrp-1003-ford-347-engine-build/

I would build a roller block but that's just me. I would also go 351W but wait...I already did...

The 331 or 347 is still a 302 block so it will use the same motor mounts and be stock height ish.......lots depend on intake and carb and air cleaner combo. For the most part it will fit under the hood fine.

Tim

 

[73azbronco]

3347 cubes, man! that will pull. Probably will need a body lift.

Seriously, welcome, I have a stroker, it was a lifelong desire as a mostly retired wrench bender. That said, I highly encourage you to go 351, and or stroke the 351. Cheaper, stronger, easier, lasts longer, maybe. Did I mention cheaper?

If you really want a stroker, buy a crate stroker, built to your desires. If you want to do it, you better have the knowledge, and a really good machinist in your pocket. Ifr you are asking here how to build a stoked block, go buy the crate motor and be miles ahead.

Cost for my stroker was about $7,500, for the longblock. 10 years ago. All the stories of strokers being bad is based on guys building these up on their garage floor and running 1/4 miles, using questionable parts and tech of the day. Modern stroke kits are fine if built properly.

If you build a stroker you need a block that has not been bored, because it will need to be bored to 30 over to align the cylinders, crank, and head.

Since it is a 302 block, it fits just like a, well, 302, no need to change any mounting. Same can be said for a 351, except the rear driver side head may hit the firewall, you can "pull" the motor forward to resolve some of this, use shorter valve covers, and or little the block a little on the mounts. a 351 also bols up to everything a 302 will, but may cause hood issues if you chose a tall intake and carb.

 

[AZ73]

If you can source a non-overbored Mexican block, it's preferred, but they are difficult to find now because everyone wants them. You might want to spend some time at Fordstrokers.com. Jim built my 347 for me. He sells parts and engines, and runs SBFBuilding.com where he shares his extensive knowledge with others including how to videos. He's somewhat of a guru on the subject. But keep in mind his focus is higher revving motors for mustangs. For a Bronco you'll want to get a specific cam which produces more torque at lower rpms. There are several good ones from comp cams or you can have one ground to your specs, like I did. But mine is based on MY specific needs related to overall weight, 5 speed transmission, 4:11 gears, and 35" tires.

I also used a new Dart block. If I was using a used block I would have kept it to 331 instead of 347, but you'll have to decide. Yeah, I looked at a 351. It's cheaper to build, but requires a number of other adjustments to the Bronco. Plus if you start getting up over 400 ft/lbs by stroking a 351 you start having to improve the entire drive-train to handle it - output shafts, axles, etc, so it's not just the motor. There's weight and working room in the engine bay, but this forum has good and arguments for and against both engines so pick your poison.

 

[Broncobowsher]

You should know that a 351W will bolt up to the same transmission options as a 302 (same bellhousing, flywheel, etc.). The motor mounts are also a match. Oil pan slightly different, etc.

Ford engineered the perfect stroker for the 302 back in the 60's. The beefed up the main bearings, oil pump drive, rod bearing size, main cap bolt size, head bolt size, etc. Pretty much any of the short comings of the 302 block were fixed when they came out with the 351W. And you can stretch that past 400 cubic inches and have a whole lot of fun with it for about what you will have into a 347.

The claims of the 347 being better are generally based on a lightweight car. A little mustang or ranchero, something like that. "It revs quicker" doesn't really matter when it is pushing a couple ton truck. At that point you just want the twisting torque of a lot of cubes.

 

[jamesroney]

Good day,
I searched the forum and didn't see anything on the 302 to 347 upgrade. I have a few questions.

Has anyone done this and if so what are your thoughts?
I want to build the engine before swapping for current 302. Will any 302 block work or do I need to find a specific one?
Will the new block slide into the existing motor mounts, etc or are there under hood modifications?
Any gotcha's I should look out for before starting?

As you can probably tell I'm brand new to this. I did a 352 to 390 swap 30+ years ago with my father but he's not around this time.
I've watched several youtube videos on the process and feel like I have decent handle on the process but it's the parts gathering I'm confused on.
Thanks.

OK...I've built a few 347's. The short answer to your questions will just make more questions. But I'll try to share some learnings:

First, there is no such thing as "a" 302 block. That's a generic term that may or may not be forward or backward compatible with a variety of 302's. The first 302 block actually appeared in a 289. Or you could argue that the first 302's were built with 289 blocks. Or you might call it a "302" because it happens to have the digits "302" cast in the valve galley. Whatever you want to call it...it has come to mean any flat tappet 4 inch bore 8.2 deck small block Ford. The OTHER block that displaces 302 cubic inches is the VERY similar 5.0 block. It is also a 4 inch bore, 8.2 deck...but it has a single piece rear main seal, and the block has extended lifter bores for roller lifters. It is also MISSING the clutch bell crank pivot, and the dipstick moved to the block pan rail. So in broad, general terms...the blocks available are:

1. 65-68 C5AE-A, C5AE-E or C6AE-C (289 blocks)
2. 68-70 C8AE-B, C8OE-A (302) block
3. 69-70 C9ZE-A, DOZE-A,B,C, D1ZE-A (Boss 302 blocks)
4. 68-7? C8AM-B, C8AZ-B, 75ZY-A, D1ZM-A (302 Mexican blocks)
5. 71-72 D1OE-A block
6. 72-74 D2OE-A block
7. 74-80 D4OE-A block
8. 78-80 D8OE-E block
9. 80-85 E0AE-D
10. 85-86 E5AE-A,C
11. 86 E6SE 5.0 roller block
12. 87-93 E7TE 5.0 roller block
13. 91-96 F1SE 5.0 roller block
14. M6010-Boss302 motorsport block
15. Aftermarket (Dart 302 etc...)

So there are at least 20 different Ford blocks that can be made into a "302" built from 1965-2000. There is ALWAYS something different that causes a change in revision. The logical split happens in about 1987.

So the FIRST question you need to answer is:
Do I want a roller cam, or do I want a flat tappet cam?
The SECOND question you need to answer is:
How fast am I going to spin this thing? (or How much Power do I want to make?)

THEN you can answer your other questions. Every block listed above will bolt into your Bronco motor mounts.

(...and the answer that MOST people get to is: E7TE or F1SE 5.0 roller block from a 87+ Mustang or 96+ Explorer)