or better measuring when ordering pistons. How about doing a 60 over 331 set up?

 

How about doing a 60 over 331 set up?

That's an option - but it would mean new crank and pistons. I'm reusing crank and pistons and putting them in the new block. Engine builder said this was better option after discussing both. Cost is comparable without giving up displacement.

I'm buying new block - builder is covering all labor and incidentals for new build. Most parts being reused. I think very fair.

 

hello;

something does not make sense.

how does a collapsed piston have anything to do with the block?

what pistons did you use?

why did woody say not to use these blocks for strokers?

thanks

.

 

Boss302 Block, which is an FRPP block not an old Boss block has shorter piston skirts. Where a stock block has a support casting hanging out below the bore, the Boss 302 block cuts them off. If the fit point is too low on the piston, you will have problems for sure.

These photos are from Fordstrokers.com



Here is the piston that is claimed to be used in the FRPP crate 347 (4.03x3.40) using that block

 

so why is it the block causing the piston slap?

 

The piston sleeve in the Boss block is shorter then the in the stock block. The bottom of the Piston moves out of the sleeve. According to Ford Racing this is not a problem - it is.

Hopefully somebody with experience can explain that better - I'm only trying to repeat what I'm told.

 

hello;

ok but you did not answer the piston question.

 

You should just go 363 since you are getting pistons again.

 

No pictures of pistons. Pistons are Diamond, they are fine just traveling too far out of block. Plan to reuse them

 

This doesn't make sense to you saying "Collapsed Pistons". Collapsed would say the skirts are damaged.

 

You can read all about the bad (and some good) experiences people have had with the ford racing boss 302 block here,

http://forums.corral.net/forums/5-0-5-8-engine-tech/1726721-331-boss-block-gasp.html

I will state it here as I have in the thread above. I race on a very regular basis. I have 367" boss 302 block engine in my car. It has a Scat forged rotating assy, Diamond 4.145" bore pistons and it's a 28oz balance engine. It has made many 9 second passes since it was built in 2007. This engine has performed flawlessly the entire time. It's consistent, reliable, it doesn't make any strange noises, it doesn't use any oil. It's no different than my stock early 70's block 347 was that I also raced for many years without a single glitch.
I have nothing bad to say about the boss block. I don't understand why so many people are having such problems with these blocks?

Brian

 

I know that many people have had good luck with it. I thought it would work for me. My engine builder built a Boss block with identical parts to mine that is fine. He is perplexed.

 

On first start up it was fine. Drove it for about 50 miles babying the throttle and keeping it below 3k rpms. All seemed good.

Interesting. Did your engine builder tell you to treat it that way?

Just asking because my engine builder told me to give it hell from the start to make sure everything seats and stuff. He told me excessive idling and casual driving wasn't good for breaking it in. I drove it like I stole it for about 150 miles then it went on the dyno for some serious thrashing.

Dean

 

Yes - because the tune was just a best guess for first startup. Didn't want to chance it going lean. The old build had different size injectors so tune was totally different

 

Same builder that put this engine together? Seems to be a trend. Time for a new engine guy/tuner if so.

 

I don't think it is fair to blame that link on the engine builder. You could blame the tuner for sure.

 

I believe the term for this is not piston slap such as in a cold forged piston before it expands due to heat but actually piston rocking when the whole piston actually "slants" in the bore.

To the op, yea was wondering about the price. I would think a dart block with machining would be more than a new rotating assembly but I don't know your internals or what your machinist/builder is charging either.

 

I was told shortly after the new Boss blocks came out that the cylinders were too short for a 3.4 stroke. Whether it works or not, it's not a good idea. It makes much more sense to start off with a different block. What Ford did, does not make any sense at all, the made the A4 block, the B50 block and the R302 block, those all had common length cylinders. For has never tried to explain why in the hell they did what they did. It really limits what you can do with those expensive blocks.

 

hello;

your cheapest way to go is sleeve the block with longer sleeves. one option is with a step on the od of the sleeve and on the id of the block.

typical cost is around $1000.00.

.

 

So the engine was built with Eagle crank and rods and Diamond pistons. On first start up it was fine. Drove it for about 50 miles babying the throttle and keeping it below 3k rpms. All seemed good.

ok no piston slap at ANY rpm including idle.

Then it was put on the Dyno. Partway through the first pull it did not sound right - stopped it. At idle you could hear a knock/tick sound. Sounded maybe like a spun bearing - but maybe different.

ok now you have noise from somewhere at idle and possibly at higher rpm.

The engine builder (same person doing the tune) kept the car to diagnose the problem... His conclusion after removing the oil pan to inspect. It is piston slap.

ok, that block csan be bored to 4.125 and you are only at 4.060.

i can positively assure you with 9.999999999% certainty, that your cylinders did not get larger. this means that the block is NOT the cause of the noise.

i would not be satisfied at all with the answer that the block is the problem. it simply makes no sense.
.

 

http://forums.corral.net/forums/windsor-engine-parts/1073409-boss-block-sale-machine-work-done.html

 

.
do you have comp cam lifters?

are you certain it wasn't a lifter or two gone bad internally. i have had them bad before installation.

 

I agree with the it being piston selection/skirt length ... even in the pictures they were different pistons ... I am no guru on these but I do think if you run the proper skirt length the piston slap issue would be less of a worry ... I think if you went to 331 stroker kit it would be even less with appropriate length skirts/pistons and maybe that is where the success stories are coming from. I agree the Dart is superior in design due to its multiple abilities and combinations on rotating assemblies ... but I don't think the Boss is junk either ... just needs a more specific set up when being stroked. I do like the idea of sleeving the block to achieve the desired length (Costly on top of block and machining) but should make for a really stout foundation as well. Nonetheless good thread ... and this is just my .02

 

Ford Racing engineers had a statement out somewhere where they said the short cylinders were designed that way so you don't have to do any clearance work for a stroker. Dart blocks have the standard length cylinders already notched for a stroker crank. Make a Boss block like that and watch the sales go up. Pic is from Fordstrokers.

 

AND! Dont forget about putting 4 Bolt caps on the front and rear!!!

if anyone could have done this easly... those Ford :leghump: crack head engineers could have.

imo Ford SCREWED UP with ALL the new "Boss" blocks.

wish i would of never bought a new boss block.

 

I believe the short bore was done to save on and streamline production by removing the extra step of machining the bottom of the bore to clear stroker kits. If so, what seemed like a good idea bit them in the rear.

I personally think an aftermarket block stroker is begging for a 3.5-3.6" stroke crank and 4.125" bore.

 

It's what happens when your "engineer" doesn't know #### about hot rods.

 

piston knock, is always the block's fault.

 

Yeah. LOL Just like it's always good to skimp on bore length for a rod length, piston pin height, and stroke.

I have a 3.443" crank that will make a nice little buzzsaw as well.

Whimp. Be a man and go 3.5-3.6" stroke.

Bet I could make a practically bulletproof 3.443" stroke FMS Boss block with a custom aluminum rod and custom piston. But, if I were to go custom rod and custom piston, I'd be using a 3.6" stroke crank and the luxury of a factory length bore. Shoot! I'd have to clearance the bottom of eight bores for the stroker!!! Might as well go back to a 3.4" stroke crank rather than deal with making 8 notches in iron. LOL

 

so who wants to sell one to me cheap since it won't work for there stroker kit? I see the shp block creeped up in price again since I checked last time.:crying:

 

cheap?

 

you want to pay top dollar for a block that's had to come apart twice and was picked up used off craigslist. :eeek: it was a joke. but he'll I'll take one if its cheap enough. got a nice 3" crank all ready that would make a nice little buzzsaw down the road.

 

.

I'm holding out for the new pro comp aluminum blocks with Nikasil cylinders and AARP bolts for just $1250.00. They say you can stroke them as much as you want.

.

 

I gotta admit man, you've been annoying me a bit as of late with your post but the above post redeems all... Lmfao!!!! Qotw!

 

Dart Block here, but you can make a Boss 347 work, but your going pay for the pistons. One I know here, but running it for years 5.40s in the 1/8th not a problem at all. Pretty sure there Diamond Pistons in it

 

 

Nikasil? ewww.

 

lol . yeah i figured only motorcycle guys would get that part.