347 research

[jlangholzj]

any of your guys got one??

I'm looking into some research about doing a 347. Thats more than likely what my next motor for my car will be. From what I can tell, most of the stroker 347 kits are based for a 302. Now isn't the 302/289 the same block?

If one of you more...knowledgeable fellas could tell me a bit more, ie stroke, piston diameter (if it needs to be .06 over or somethin)...etc...


I've heard that they make low end torque like non other...but I'm also trying to remember if the 347 is where you had to do some notching to allow for clearance.

again...general info.


thanks guys!

 

[BlownFiveLiter]

The 347 is a 302 based stroker. To the best of my knowledge, the 289 and 302 share the same block, but the 289 is a 2.87" stroke, versus the 3" stroke of the 302. With a 347, it's 4.030" bore and a 3.40" stroke. You do have to clearance the bottoms of the cylinders for the rods, but other than that, it shouldn't take any unusual machining. The only important thing to look out for that I know of is whether it's an early non-roller block, or late model roller block, so you can run a hydraulic roller cam without using retrofit lifters, or a reduced base circle cam.

 

[blown65]

You can also get from CHP different piston rod combo and go with 5.315 rods and 3.4 stroke crank.

10666-SF-F347 - Ford 347 Flat Top -4.0cc Street Fighter Engine Kit


I'm doing something similar when I change to a turbo setup, but with 4.155 bore pistons.

 

[coolblue65]

In addition to the above, the early blocks have a 2-piece rear main seal and will have a bolt hole to be able to bolt in the mechanical clutch linkage, late model blocks will be a 1-piece rear main seal, and will not have that hole and you will have to use an adapter.

BTW- I LOVE MY 347!

 

[jlangholzj]

You can also get from CHP different piston rod combo and go with 5.315 rods and 3.4 stroke crank.

10666-SF-F347 - Ford 347 Flat Top -4.0cc Street Fighter Engine Kit


I'm doing something similar when I change to a turbo setup, but with 4.155 bore pistons.

In addition to the above, the early blocks have a 2-piece rear main seal and will have a bolt hole to be able to bolt in the mechanical clutch linkage, late model blocks will be a 1-piece rear main seal, and will not have that hole and you will have to use an adapter.

BTW- I LOVE MY 347!

woah woah waoh here fellas....we're gettin all complicated on me...lol.

first of all, blown, what exactly is the benefit? from what i can gather...is it a higher compression with the 5.315 rods and 3.4 crank?

i guess it would help if i looked up the stock dimensions of the 289.

btw...this is an early 289...ie..'68 issue...lol.

 

[Decurion]

If youre using a 289 block, it more than likely has shorter cylinders which makes the pistons come further out at the bottom of the stroke when using a 347 crank (3.400" stroke). Some people may not have a problem with this as I know its been done, but I dont think I would do it for my own engine. If I was using an early block, I think I would stick to a 331 (3.250" stroke) to keep the pistons a little more in the cylinders at BDC. Best thing to do for bore is only go .030" over. .040" is probably fine, but at .060" youre really pressing your luck. With a 3.250 stroke you may or may not have to notch cylinder walls, but you will with a 3.400 stroke.

 

[woodsnake]

Also it is possible to machine a 289 block to accept a one piece rear main seal.
It might not be cheap, but can be done. Talk to your machine shop guy for pricing.

 

[Decurion]

No offense Decurion, but I must debunk this myth once again. Not true. It just never happened although Ford had the "longer bore" statement on a early 302 brochure back in the 60s (the most likely source of the myth). Measure your cylinder depth on that 289 block if you have it disassembled and you'll find it to be 5 1/8" deep within a sixteenth or so. I've measured blocks just to verify it and there is no difference.

Well I'll be a monkeys uncle! View attachment 248857 I had always heard they were shorter. The 289 was a little before my time anyway, Ive always had 302/5.0Ls. I still wouldnt do a 347 tho, if only for personal feelings.