Early B6 and B3 differences?

[sketchman]

I can't find a post that shows anything definite saying you can't take the B3 to 78mm. I measured it once and found the opposite, BUT I didn't cut a block up to get a definite answer. I just mic'ed #1 wall through the water pump hole, so it wasn't a solid answer by any means.

I've read on here that the FSM gives nominal wall thickness. Personally, I can't find it in mine.

I've read elsewhere that the B6 doesn't mind being bored over 3.5mm and then being boosted to 23.5psi and DDed hard.

Till I see a B3 cut up, I can't quite believe it won't go to B6 proportions with ease.

YMMV

[blkfordsedan]

I've never seen a factory block that would accomodate a .27X" over-bore. I've taken a 352 FE block out .130" to a 428 bore successfully, but I was sweatin' bullets. The cost of machine work alone to cut that much would be more than a used B6 block. You could have a B3 block sonic tested to find the thinnest spot if your brave. Could also fill the water jackets half full of block filler. But, why do all that when you can safely use a B6 block?

[Advancedynamix]

I'd just use the B6d block (and rods if they fit with the press in style wrist pins). I have a new b6 crank .20 over pistons, rings and pins. I just don't have a B6 sohc block. I bought the lot of parts cheap from a guy who had a B6 tracer he sold before rebuilding. All good parts, Clevite and original ford parts. Couldn't pass the deal up. I thought I could punch out my B3 block, but it does make sense that there isn't enough iron there for that much overbore. I have several spare b6d blocks, so I'd like to use that block if I can. I've heard stories of B3 and B6 sohc engines seizing the wrist pin in the rod (under extreme abuse) but this could be avoided with the oil squirters. The valve reliefs would be in the correct location because I'd use these B6 8V pistons. I can surface the block if the deck height is too high. If it's too low I can machine the combustion chambers. I haven't had a B6 sohc block apart, so I'm not sure what they look like inside, but the B6D is a stout little block (not compared to it's "strong enough to be a diesel" bigger brother, but still very stout.)

Thanks again for all the info on this. It saves me a bunch of time at the salvage yard.

[Advancedynamix]

I've never seen a factory block that would accomodate a .27X" over-bore. I've taken a 352 FE block out .130" to a 428 bore successfully, but I was sweatin' bullets. The cost of machine work alone to cut that much would be more than a used B6 block. You could have a B3 block sonic tested to find the thinnest spot if your brave. Could also fill the water jackets half full of block filler. But, why do all that when you can safely use a B6 block?

I wouldn't. lol. I had heard that the B6 and B3 were on the same block, so I wasn't sure if it could be done. Not a big deal.

The BMW M-10 block will accept over a .300" overbore (in it's european 1.6 liter form). These engines were built all the way up to 2.5L displacement from the factory (S-14 is essentially an M-10 casting).

[blkfordsedan]

I'd just use the B6d block (and rods if they fit with the press in style wrist pins). I have a new b6 crank .20 over pistons, rings and pins. I just don't have a B6 sohc block. I bought the lot of parts cheap from a guy who had a B6 tracer he sold before rebuilding. All good parts, Clevite and original ford parts. Couldn't pass the deal up. I thought I could punch out my B3 block, but it does make sense that there isn't enough iron there for that much overbore. I have several spare b6d blocks, so I'd like to use that block if I can. I've heard stories of B3 and B6 sohc engines seizing the wrist pin in the rod (under extreme abuse) but this could be avoided with the oil squirters. The valve reliefs would be in the correct location because I'd use these B6 8V pistons. I can surface the block if the deck height is too high. If it's too low I can machine the combustion chambers. I haven't had a B6 sohc block apart, so I'm not sure what they look like inside, but the B6D is a stout little block (not compared to it's "strong enough to be a diesel" bigger brother, but still very stout.)

Thanks again for all the info on this. It saves me a bunch of time at the salvage yard.

The SOHC block is pretty stout as well. My B6 had ~.003" deck clearance with factory pistons, so you should be good. Should be 9:1 with factory 5cc dish pistons and a standard .057" head gasket. If you use a Cometic MLS gasket for the early B6D, it should put you around 9.5:1.

If you have an unmolested SOHC B6 head, I would love to get a good volume measurement on the stock chambers...I'm guessing they're ~37cc.

[Advancedynamix]

I already have a 1mm Cometic head gasket, so that's easy. I'll try to find an 8 valve b6 head that looks original to get a volume for you. I prefer heads that have never been off the engine anyway, tells me the casting is trustworthy (as long as the gasket isn't blown and there are no indications of overheating.) A stable casting makes a huge difference in engine longevity.

[gauge_half_inch]

I only a couple of pics left from my early b6 teardown.


Hope these are helpfull.

[blkfordsedan]

Yep......looks like mine, LOL.

I usually grind the casting lines off the main webs and polish them, but considering we're talking about 100hp at the most and a block that can
probably take 3X that amount, I just left everything stock. The only thing I
did do to the block was grind all the excess casting flash out of the oil return
passage. There is a lot of flash located right at the bottom of the passage (see pic below)...and it never hurts to improve oil return to the pan.

[Advancedynamix]

Thanks for the pictures guys. They look like a b6d/t/ze block without the squirters. Does that block have the provisions for oil and coolant feed lines on the front like the b6d has?

[gauge_half_inch]

Not from my inspection.