Mustang Boy
Well-known member
i know its only been a few weeks but do u have any updates on the progress of this radical project
Big cubes in a small six block
- Thread starter AzCoupe
- Start date
I'll issue a challenge. If Small Block guys can aggree to do a fat bored and stroked 250 taken out to 320 cubes, then there is no reason why you Big Block guys can't do a fat 383 six.
Mike has a beaut alloy head for his, while 6banger has a great alloy head for the 300 block. Why waste either of these on little 250 or 300's?
Some background rules.
The rule with even thinwall blocks is 3/16 oversize, plus 60 thou. 250 thou bigger bores is not exactly easy, but close! 109 and 122 cube Escort BDA's were just thin wall 97 blocks bore and sleaved. This is becasue the cylinder walls have to start off with a 120 thou thickness at the start of it's service life. At the worst, some Clevelands with some core shift could go down to 90 thou wall thickness. A 90 thou thick sleave is the bore size plus two thickness wide. So a 4" bore has to have a 4.180 thou thick sleave, and it will split under high compression and revs. 120 to 180 thou is the ideal size for an unsupported wall engine. If you can add Hardfill or the modern equivalents, then you could possibly use the stock 87.5 thou thick sleavs used in some dry sleave diesel trucks.
The US 250 block has a camshaft further out than the Aussie 250, so it could take a stroke close to the 4.175" that the Mopar 225 uses. The SloPar has room for a 4.5" stroke. If the US 250cam centre to crank centreline spacing is similar to the Mopar 225, then you can reach 4.5" stroke!
They were doing fat bored sixes back in Aussie in the late 50's, early 60's with Hoden engines, adding sleaves with 0.5" thick plates on top of the block to create engines up to 30% bigger, boring out the entire cylinder wall, and screwing in 3/16 liners.
The block, ( and any 200/250 block that is not intersected by a camshaft) can take steel boiler tube in 4 1/8" size, with a broached thread to screw the liner in, rather like the old Hispona Suiza engines. You need 180 thou of wall thickness at the thrust faces if its low grade steel, could go down to 120 thou thick if you use some kind of higher quality Thad style drill rig tube.
A low deck 3.930 LS-1 Chevy piston would work.
A six is a really easy engine to make from plate steel and boiler tube because of its simple bulkheads and simple froms. I spoke with SuperMag a year ago regards a guy, Bob St Lawrence, who made his own 392 Hemi engine block in Australia, and decided that I was going to build a diesel block out of a 250 gasoline engine.
I ditched the plans due to other projects, but I'll post the article.
On the other note, why would you have a even a 305 cube 3.9375" by 4.175" Small Block six when you could have a 4.06" by 4.5" stoke 350 cube Big block six?. Our Big Block guys have a block based on the old 4.375" stoke 226, so if we can go for 305 to perhaps 320 cubes with sleaves, then they could do a 383 with just a crank and some fat sleaves.
A new axis of evil has begun!
Mike has a beaut alloy head for his, while 6banger has a great alloy head for the 300 block. Why waste either of these on little 250 or 300's?
Some background rules.
The rule with even thinwall blocks is 3/16 oversize, plus 60 thou. 250 thou bigger bores is not exactly easy, but close! 109 and 122 cube Escort BDA's were just thin wall 97 blocks bore and sleaved. This is becasue the cylinder walls have to start off with a 120 thou thickness at the start of it's service life. At the worst, some Clevelands with some core shift could go down to 90 thou wall thickness. A 90 thou thick sleave is the bore size plus two thickness wide. So a 4" bore has to have a 4.180 thou thick sleave, and it will split under high compression and revs. 120 to 180 thou is the ideal size for an unsupported wall engine. If you can add Hardfill or the modern equivalents, then you could possibly use the stock 87.5 thou thick sleavs used in some dry sleave diesel trucks.
The US 250 block has a camshaft further out than the Aussie 250, so it could take a stroke close to the 4.175" that the Mopar 225 uses. The SloPar has room for a 4.5" stroke. If the US 250cam centre to crank centreline spacing is similar to the Mopar 225, then you can reach 4.5" stroke!
They were doing fat bored sixes back in Aussie in the late 50's, early 60's with Hoden engines, adding sleaves with 0.5" thick plates on top of the block to create engines up to 30% bigger, boring out the entire cylinder wall, and screwing in 3/16 liners.
The block, ( and any 200/250 block that is not intersected by a camshaft) can take steel boiler tube in 4 1/8" size, with a broached thread to screw the liner in, rather like the old Hispona Suiza engines. You need 180 thou of wall thickness at the thrust faces if its low grade steel, could go down to 120 thou thick if you use some kind of higher quality Thad style drill rig tube.
A low deck 3.930 LS-1 Chevy piston would work.
A six is a really easy engine to make from plate steel and boiler tube because of its simple bulkheads and simple froms. I spoke with SuperMag a year ago regards a guy, Bob St Lawrence, who made his own 392 Hemi engine block in Australia, and decided that I was going to build a diesel block out of a 250 gasoline engine.
I ditched the plans due to other projects, but I'll post the article.
On the other note, why would you have a even a 305 cube 3.9375" by 4.175" Small Block six when you could have a 4.06" by 4.5" stoke 350 cube Big block six?. Our Big Block guys have a block based on the old 4.375" stoke 226, so if we can go for 305 to perhaps 320 cubes with sleaves, then they could do a 383 with just a crank and some fat sleaves.
A new axis of evil has begun!
Somewhere there's a thread in here where my machinist and I did some "bench racing" on the same subject. I thought a 4" x 3.13", big bore 200 small six would be really cool. We did some measurements and we figured we could get sleeves to fit by milling the sides flat so they would fit together. They would be wet liners. A copper head gasket would seal the deck.
Then we figured up the cost, added in the lack of a good head, and decided that a 4" x 3.13" big block 240 would be easier...
That whole line of thinking could change if a really good head were available.
Then we figured up the cost, added in the lack of a good head, and decided that a 4" x 3.13" big block 240 would be easier...
That whole line of thinking could change if a really good head were available.
A
Anonymous
Guest
so any more news on these big cube small sixes?
Not much to report at this time. Only that we trashed two blocks and a couple sleeves. Looks like the 4.00 sleeves aren't going to go in, however the 3.875s should work fine. So we ordered more sleeves and were busy tracking down a couple more blocks. Might be able to hit it again sometime next week. I'll keep you posted if anything of value happens.
hey
whould it possible to fir these sleaves in a aussie crossflow block?
also what whould the block likly be like for speedway use as i think it whould give quite a rude shock to the inject v6 buick(holden) engines in say a cortina.
and what of this new head 3 valve or 4valve (both of which whould be possible if starting with a fresh bit of papper and useing bridges for the valves like cat do on there 3406 c15 c16 3176 c10 c12 engines?) or are you chassing the hemi route? i see you are starting from a 2v head base.
it could be that the log motor will surpase the crossflow for power and parts aviable very son if this development keeps up.
skid
whould it possible to fir these sleaves in a aussie crossflow block?
also what whould the block likly be like for speedway use as i think it whould give quite a rude shock to the inject v6 buick(holden) engines in say a cortina.
and what of this new head 3 valve or 4valve (both of which whould be possible if starting with a fresh bit of papper and useing bridges for the valves like cat do on there 3406 c15 c16 3176 c10 c12 engines?) or are you chassing the hemi route? i see you are starting from a 2v head base.
it could be that the log motor will surpase the crossflow for power and parts aviable very son if this development keeps up.
skid
I think he's treading water on this one at present. You may have read last week or so, that business premises where they were doing R&D for this stuff had been sold, and Mike was forced to pack up his toys and move them out.
Plus, considering the level of hand-work in finishing off the valve cover deal (running around, liaising, packing, mailing) it's not hard to see where the time's all gone. Consolidating gains at this stage is probably more important than a side project...
Plus, considering the level of hand-work in finishing off the valve cover deal (running around, liaising, packing, mailing) it's not hard to see where the time's all gone. Consolidating gains at this stage is probably more important than a side project...
All,
Just to give you some info on this....or at least my take on it.
Because of the machine shop closure, a block, crank, and rods are at my house now. Custom JE pistons still need to be ordered.
We will be working on this kinda in the "background" as a side project.
There is still a lot of work to do on it. I believe we're going to stay with a .040" overbore, but the stroke is longer to give us around 275 cid.
I'll keep you informed as we make progress on it.
Later,
Will
Just to give you some info on this....or at least my take on it.
Because of the machine shop closure, a block, crank, and rods are at my house now. Custom JE pistons still need to be ordered.
We will be working on this kinda in the "background" as a side project.
There is still a lot of work to do on it. I believe we're going to stay with a .040" overbore, but the stroke is longer to give us around 275 cid.
I'll keep you informed as we make progress on it.
Later,
Will
Mustang Boy
Well-known member
do u know if FSPP will be offering "stroker" kits so we could increase our stroke
Similar threads
