289 better than 302 block for 331 build?

[Jesse Kershaw]

I would like to clear the air on the "short" cylinder walls because it's a common misconception.

We have sold thousands Boss 302 blocks, and 347 strokers, now 363 strokers, built off the Boss 302 block. We use a 347 for our sealed circle track program since 2008 with the Boss block. We have never had a failure from piston instability or anything related to the short cylinder wall length. All of these are done with 5.4" rods, if you're trying to do a bargain stroker with stock 302 rods then why look at a new block?

We shortened the wall for weight and to ENABLE stroker engines so they didn't have to grind for clearance depending on what crank they used. I am aware of a handful of 3.5" stroke engines in the ~370cid range also that have never had an issue. In fact our prior director Brian Wolfe had a 3.5" stroke in his personal Boss 302 block engine.

Due to early claims from many engine builders about the cylinder wall length we ran a second durability on the block and 347 crate engines about a year after its initial release. 1600 laps in a circle track for one, and 30 hours of dyno time varying between idle, peak power and peak torque for another. The result was perfectly fine blocks and pistons.

I have contacted 4 different shops that alleged to have failed engines with the block and upon investigation they had never even built one OR had built one and it never failed.

I can think of one customer who built his engine with a Boss 302, scuff a piston and immediately blame the block because of internet chatter. I spoke to him personally at an event. I asked for more info, like pictures? Are the ringlands intact? Are there signs of detonation? What was the piston to bore clearance? I never heard back again.

The Street Rodder 2008 Road Tour car ran a Boss block 347 and drove all over the country and then some. It's never had a single issue and the program director Jerry Dixey told me that it was the easiest engine he had to date because he never had to touch it during the trip. This year they are doing a new 5.0L in case you're interested.

Our 2010 Cobra Jet 352cid combo is a 3.4" stroke with the Boss 302 block as is our 2013 363 combo. Those have proven very reliable on the track.

I admit that at first glance the Boss 302 bore looks different but if there was truly this massive issue we would have changed the block or stopped selling 347/363's long ago. We cannot afford engine failures against our brand.

Everything above is fact.


Now for my opinion...

I believe this rumor about block failures is largely the work of our competition and their distributors who have a vested interest in selling their product. Shortfalls in their product have been brought to my attention but I would rather talk up the benefits of ours like the grade of iron, the crossdrilling between cylinders for street cars, finished lifter bores, and value vs. performance.

I also believe that if your engine builder is convinced that something isn't what they like, and your engine fails they will point to what they didn't like whether it was relevant or not because it's no money out of pocket for them. There are plenty of builders that love the Boss 302 block or we wouldn't continue to sell them like we do.

Thanks for your consideration.

-Jesse

[SSDiv6]

Jesse,

Is there a good reason why you guys discontinued the M-6010-R302 block?

[RJ Sledge]

Jesse

Thats good to hear. I was only stating my opinion and that is why we started off with a New 302 "R". I have seen problems with severe pistons scuffing on a 289 SS combo using the Boss block and the engine builder brought the short cylinder issue up. He does not have that problem with a older style 289 block.

RJ

[BlueOval Ralph]

When you build 302 stroke combos Piston skirt design in VERY important, the more stroke the more important it becomes! It may not affect durability but it in the area of piston stability and ring seal.

[Jesse Kershaw]

SSDiv6,

We discontinued to R302 because it was replaced by the Boss block which we believe is better in every way. The iron is better, core shift is essentially non-existent, oiling and cooling is revised and improved, cost came down, etc.

The R302 tooling as I recall was getting old and we sold the last of our production blocks and Sportsman blocks. The Boss 302 was designed to replace both our race block and the Sportsman. For us to have rehab'd the R302 tooling would have been an inferior block for more money.

In regards to other posts I agree that piston skirts can make a big difference. We use Mahle pistons and have had great results.

[SSDiv6]

Originally Posted by Jesse Kershaw

SSDiv6,

We discontinued to R302 because it was replaced by the Boss block which we believe is better in every way. The iron is better, core shift is essentially non-existent, oiling and cooling is revised and improved, cost came down, etc.

The R302 tooling as I recall was getting old and we sold the last of our production blocks and Sportsman blocks. The Boss 302 was designed to replace both our race block and the Sportsman. For us to have rehab'd the R302 tooling would have been an inferior block for more money.

In regards to other posts I agree that piston skirts can make a big difference. We use Mahle pistons and have had great results.

Thank you for the explanation Jesse.
By the way, is there a way I can obtain a copy of the instruction sheet for the M-6010-R302 block?
I own two R302 blocks, however, I do not have the instruction sheet that contained all the particulars about the block, including the toque values for the fasteners.

[rawhide]

The instruction sheet for the R302 is a one page deal and is not available on the Ford Racing website. If you have a fax send me the number and I will send it to you. I would scan it if I knew how but my knowledge of computers is on-off-porn
regards