I have been gathering up parts and I am very near the beginning of the building of my 347. It will be a torque motor, NOT a high RPM race motor or even a high RPM street motor. It is HIGHLY unlikely that this engine will ever see 5,000 RPM and probably rarely not even above 3,500.

I have two parts cars, one with a 289 and the other a 302. Logistically it will be much easier to use the 289 block since I will be pulling it anyway to get some other drivetrain parts. It would save having to push the parts car with the 302 out of the field and onto the lift.

I have read debates as to whether there is indeed any difference between the 289 and 302 blocks. I have read that the bottom of the 302 cylinder extends an extra 1/8" at the bottom, but I have measured and found that to be a difference of less than .100", at least on the particular blocks that I measured.

This being an early Mustang forum, surely there is someone here who has used their 289 block as the foundation for their stroker motor. If you have done this, what was your experience.

I just hate to go through all the extra hassle to retrieve the 302 block if it's not necessary.

Thanks for your feedback.

 

One of my old coworkers built a 450hp 347 from his original '66 289 block. It works great

I've talked to several people who've measured side by side and they've found no difference, or at least nothing that couldn't be explained by the block being decked.

That said, I'd use a roller 5.0 block if you can find one. Roller cams make life easier in all respects.

Also, why not build the engine to run to 5500? You can build a pretty solid 347 that winds to 5500 to make a good amount of power but won't be lacking in bottom end. A roller cam would make it even easier.

 

Normally I would agree with the 302 roller block for a street engine, but given the fact that a 289 block is readily available for you go ahead and use that given the block specs out fine. I have found on 289's especially that they seem to have more core shift and heat cycle problems than do the later 302 and 351w castings. I just take a spec cam of known dimension on each lobe and degree the cam on all the cylinders, if it specs out the same you can be pretty assured your good to go if not or you have some lifter bind than you might look into going for another block.

 

it woudl be interesting to know. There have been loads of debates about 289/302 differences but not a single person could ever prove there is one. let us know how you're getting on

 

well this guy is saying he measured about .100 difference. if thats the case i would use the 302 block as the more cylinder skirt you have the better.