Sleeved Boss 302 block

Andy FIA · #1 (**permalink**) 03-19-2002, 05:22 PM

I have been offered a Boss 302 block that has two sleeves installed, I haven't seen it yet and I don't know how much it will be!! (the owner thinks its in storage somewhere!)

Should I consider a Boss block with sleeves?
If so, what should I look out for?
How much is it worth?

Andy

Toivo · #2 (**permalink**) 03-19-2002, 05:34 PM

others may know more about this, but as far as I know, the only difference between a Boss block and a normal 302 block from the same year are the screw-in freeze plugs and 4 bolt mains.

Is this JUST a block, or does it include a crank as well?

Unless you're looking for a numbers-matching piece I wouldn't value it any more than a regular block. Even the 4 bolt mains aren't all that important; at least not to me. I think that unless they're splayed anyway, they actually weaken the bottom end, you'd be better off with 2 bolt mains and a girdle.

Just my opinions. I know some people place a lot of value on being able to say things like "it's a Boss block" with "4 bolt mains" yadda yadda yadda. At the end of the day, it's just another block that's seen better days.

again, JMO

bmalone · #3 (**permalink**) 03-19-2002, 08:16 PM

Hi Andy:

As Toivo said you can identify the block by the screw-in freeze plugs.

Benefits of the Boss block in addition to four-bolt mains:

Cast of higher nodular iron, with thicker cylinder walls. Not sure why your block would have two sleeves, something to think about.

'69 Boss crank is cross-drilled steel (best). The '70 was a steel crank, but not coss-drilled (two oil holes per throw).

Boss rods were 3/8" diameter bolts compared to 5/16" (weak point) on all other blocks.

Solid-lifter cam.

Since you might replace the internals such as pistons, rods, even crank, the benefits of this block boil down to better main cap design and stronger and beefier block.

THe cylinder heads are to die for if you can get them. They offer 2.19" intakes and 1.71" exhaust valves (big as big block).

Bill

jmarsey · #4 (**permalink**) 03-19-2002, 09:41 PM

Hi Andy,

Most of the above is true. The 69 cross drilled crank is not the best. They had cracking problems at the cross drilled locations in trans am cars. The 70 crank is the one to have if you must know.

The Boss thing is best left to the guys with the b2 mustangs period. At best, these blocks, although great in the day, are only good for 550 to 600 hp. You're better off with a replacement block, steel main girdle and a well balanced rotating assembly. Also the Boss block is in no way the same animal as an R-block. Night & day.

I would not invest time and money in a sleeved b2 block.

John

ps, to answer your question, the sleeved block is not worth much.

Andy FIA · #5 (**permalink**) 03-20-2002, 04:43 AM

Thanks for the advice fella's, I might buy it if its really, really cheap, but somehow I don't think it will be! otherwise I'll stick with a beefed up "girdled" two bolter for my stroker project.

Andy

jmarsey · #6 (**permalink**) 03-20-2002, 09:17 PM

Hi Andy,

If you're thinking of a small block stroker, I would recommend the 331 combination and leave the 347 to the drag race boys. The rod angle on the 347 is too severe. just my 2 cents.
John

Steve R · #7 (**permalink**) 03-21-2002, 11:38 AM

Andy,
If you are hell bent on a strong 302 block, buy a new one from Ford Motorsport that has the 4bolt mains. If the block you are talking about is servieable, It may be worth something to a guy who is restoring a Boss 302 mustang. The sleaves give me the creaps.....why are they there? It would probably be a foolish gamble to invest you hard earned money building an eng around it. If I could get it real cheap, I would probably buy it just as a conversation piece.
My 2cents
Steven

Mike Braddock · #8 (**permalink**) 03-21-2002, 08:10 PM

Andy,

Good question indeed. Just because a block has sleeves, does not mean it should be written off. IF they were properly installed. Hmm...that sounds like a risky IF, doesn't it

?

What is your target HP on your new motor? Unless you are trying to make more than 400 fwhp, you should be fine with a regular 302 block--even a later model block (which is weaker than the older ones). Of course the benefit of the late model blocks is that they are already set up for a roller cam. If you are worried about block strength (or emissions legality), go with an older block, the best being the 'Mexican' blocks, which are becoming quite scarce but they're still out there if you are persistent. If you really want to make silly hp, step up to a used A4 or R302 block, which can be purchased for between $800 and $1400 depending on condition (finished machined, sleeved, etc.).

I also agree that the 331 will make for a longer lasting stroker. Then again, a stock stroke 302 will rev a little faster and a little higher, so it's all a matter of what you want. Personally, before you run into block strength problems, I think you'll have head gasket worries. Which is probably a good thing, as they act as a fuse before you really start breaking things

. It's been shown that an old Mexican 302 block with good fasteners can make upwards of 450 fwhp and live a long happy life.

Sorry for all the babble. One last point; perhaps the most important of all. The Boss block will have the canted valve reliefs, which will play havoc with your upper stroker piston rings, since the wrist pins (and hence top ring lands) will undoubtedly be quite high to maintain a decent rod ratio. One of my friends found this out the hard way

. $450 and 8 sleeves later, he was back on his merry way

. On the other hand, he did manage to make 470 rwhp with that bottom end (331 ci), a set of 2V cleveland heads and an S-trim Vortech...

Mike

Andy FIA · #9 (**permalink**) 03-22-2002, 05:25 PM

I do not envisage going above about 400 HP at the flywheel as the compression ratio will be limited by the fuel we have over here, so a 2 bolter would be OK. I do like engines that rev so maybe the 331 would be preferable over the 347.

Here in the UK it is not common to sleeve any kind of block, probably due to cost, so I have had no experience of this myself and do not know of anyone else running a relatively high performance motor with an iron block that has been sleeved.
I still do not have a price on the Boss block yet.

Andy

RICK LAKE · #10 (**permalink**) 03-23-2002, 07:39 PM

Hi Andy My 2 cents. The boss block has screw in water jacket plugs the block also has a higher nickel content than the standard 302. There are different pistons in the boss 302 because of the polyangle wedge staggered valves. The intake valves are larger in the 69 heads than the 70 heads. My Shelby motor came with 8 cylinder selves in it, and I have no problems. I know of a couple of engines that have 6 and 7 sleves in the block without a problem. If the sleves are installed correctly their should be no problem unless you are looking for 600 hp and 8000 rpm. Buy the motor. You can always save it for a spare. I have a short block spare with 3 sleves in it. Good Luck. Rick Lake

fia#09 · #11 (**permalink**) 03-28-2002, 03:58 PM

Andy, lots of opinions, how about this one from Mustangs and Fast Fords, March 2001, article: Stroker Theory. "Blocks-- a better choice for an all out race engine is a Boss block or the Ford Racing A4 or R-302 block. The Boss and the Ford Racing blocks feature ...are... beefier and designed to make well over 850 horsepower." After all the reading, etc, I am content that my Boss is one of the strongest bottom ends Ford ever made. Another consideration would be to duplicate the 70 Trans Am motors, they won the championship on 10:1 compression, and if my memory serves me correctly, they went the entire season without a single engine failure. Also, I have a 69 motor with the cross drilled crank, which is generally recognized as the best crank ever in a small block Ford. In all my research I never heard of a crack failure. There is nothing wrong with sleeving a block, so long as its done correctly. All aluminum blocks have sleeves--Porsche, Nissan, Ferrari, Corvette, on and on. All that you need to know is that it was done correctly. Incidentally, my machine shop told me that a Boss crank weighs about 10lbs more that the standard 289/302 crank. If that block were available here, I would snap it up for the right price in a minute. The Boss parts have high intrinsic value to the collectors--insurance for you against depreciation.

jmarsey · #12 (**permalink**) 03-28-2002, 11:28 PM

1. 69 crank failure is documented.

2. Boss block is the weakest of the three and a little better than 1/2 the strength of the R-Block.

3. 70 Bud Moore Trans Am cars ran 10.5:1 and made between 460 - 490 HP. You'll need some Trans-Am rods, Bud Moore Mini-Plenum intake (which I have if interested), 850 holley, fairly nasty flat tappet cam .600/ 324, some head work like raised intake runners (which you won't read about) and light weight valve trane and a few other odds & ends.

John Marsey

wpasicznyk · #13 (**permalink**) 03-05-2004, 09:25 AM

You will find many Boss 302 blocks with cylinder cracks because there was a piston skirt problem with the original pistons which was mostly fixed by the 1970 model year. The pistons crack, come apart and crack the cylinders. There was a Ford recall on the pistons and anyone who had an engine break because of this got it fixed under warantee regardless of age, because of the recall. This put a lot of cracked blocks out there.

Also, I presently have a Mexican 302 for sale. If you're interested e-mail me for photos. It has no ridge on the cylinders and is presently at 4.000" ID. Has surface rust and no cracks.

wpasicznyk@crest-ultrasonics.com