8BA tooling.

[Tod]

Originally Posted by Bored&Stroked

That is probably true, but only if using the block in a 21 stud application and they are drilled out. In the case of the typical 24 stud usage, the cast bosses would be below the deck, but not used. Therefore, we can "hopefully" bore all the way to 3 7/16 and still have decent cylinder wall thickness. I'd love to go to 3 1/2", but this starts to make head gasket sealing an issue.

Hmmmm . . . maybe I'll think about high quality 3/8" 'step studs' and go to 3 1/2". I'll have to look into that!

Right. I can have a machining program for blocks with 21 studs and one for 24. There are some bosses that will need to be elongated because bosses for the 21 and 24 are pretty close together in a few spots but not close enough to use the same round boss.


Tod

[flatheadmurre]

Originally Posted by Bored&Stroked

That is probably true, but only if using the block in a 21 stud application and they are drilled out. In the case of the typical 24 stud usage, the cast bosses would be below the deck, but not used. Therefore, we can "hopefully" bore all the way to 3 7/16 and still have decent cylinder wall thickness. I'd love to go to 3 1/2", but this starts to make head gasket sealing an issue.

Hmmmm . . . maybe I'll think about high quality 3/8" 'step studs' and go to 3 1/2". I'll have to look into that!

Calculate the minimum thread that will hold up and machine the block for it ??

[Yoyodyne]

I've pondered how to build a big bore engine with water pump heads. If Tod would sell a block with all the bosses in the right place but the head stud pattern drilled for 24 stud, or perhaps undrilled, you could drill the extra studs for 21 stud heads slightly offset away from the cylinders. I was poking around under the deck of a late block and wishing for some material to appear right there, that would have solved my block availability problem.
I think there's enough metal in the iron heads to relocate those holes by stepped sleeves. Aluminum 21 stud heads could maybe be ordered without those holes drilled. I wonder why Ford added studs instead of just relocating them, anyone here have sealing problems with 21 stud heads in that area?

[37 Cab]

It still needs to breathe. I just wonder how well a 3 1/2 engine would breathe even ported.

[Ol' Ron]

I can't believe we're talking about boring this to 3 1/2", when no matter what we do with the ports we won't be able to feed it. Assuming the de ck thickness is increased, you don't need much of a bung for 21 stud heads. I torque ALL my heads to 45 ft/lbs, over 3 heat cycles and have NEVER had a problem. This is like walking into a new car dealer and trying to buy an economy car with all the options, and the price goes out of sight. 90% of the buyers here will just wand a good running engine at a reasonable price. Course, a blown 340 ci Flathead would be nice.

[pooch]

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Originally Posted by Yoyodyne

I've pondered how to build a big bore engine with water pump heads. If Tod would sell a block with all the bosses in the right place but the head stud pattern drilled for 24 stud, or perhaps undrilled, you could drill the extra studs for 21 stud heads slightly offset away from the cylinders. I was poking around under the deck of a late block and wishing for some material to appear right there, that would have solved my block availability problem.
I think there's enough metal in the iron heads to relocate those holes by stepped sleeves. Aluminum 21 stud heads could maybe be ordered without those holes drilled. I wonder why Ford added studs instead of just relocating them, anyone here have sealing problems with 21 stud heads in that area?

We have a local guy here who makes new alloy 34 stlye heads with pump in head.

He has them cast and does all the machining himself.

I am sure he could change them a bit if needed.

[Bored&Stroked]

Originally Posted by Ol' Ron

I can't believe we're talking about boring this to 3 1/2", when no matter what we do with the ports we won't be able to feed it.

Well . . . that may be true given the current stock Ford block situation, but if Tod changes the intake ports and this enables us to improve the flow, then I can't help but think the ports can deliver more flow to the bore. Also, I'm a big fan of supercharged engines - where the blower makes up for some of the lack of flow in the ports. In the end, cubic inches always come into play - at least on the extreme ends of performance.

What I'm trying to say is that if Tod can design a block that handles everything from stock, to high performance, to extreme high performance . . . and not punish the low-end guys with added costs, then we have a "win-win" situation. Guys like me who want to push the limits (which is why I'd buy this block) are happy . . . and those who want a better than stock replacement are happy as well.

It is hard to walk the "fine line" between stock replacement and extreme performance - but I believe it is possible if the block has the necessary design and associated material thickness to allow guys like me to experiment.

Don't penalize the guys who want quality stock replacements (with unnecessary cost or complexity) - but open the door for the goofy bastards like me that push the performance boundaries.

Okay - that is enough of my babble!

B&S

[Henry Floored]

I think a 3 1/2” piston will help the engine breathe. The more of that combustion chamber that is “active” and the closer to the edge of the cylinder wall is to the intake valve the better it is.

[40 Deluxe]

Originally Posted by Henry Floored

I think a 3 1/2” piston will help the engine breathe. The more of that combustion chamber that is “active” and the closer to the edge of the cylinder wall is to the intake valve the better it is.

Remember, air is not "drawn" or "pulled" into the cylinder, it is pushed in by atmospheric pressure (or boost pressure, if supercharged). This distinction must be kept in mind when visualizing air flow through a port. Air has mass (as does the fuel suspended in the air) so therefore has inertia and loses velocity as it makes all those turns through the intake tract and past the valve. So this is a bigger factor than the edge of a cylinder wall being a 1/16" or an 1/8" closer to the valve.

[Ol' Ron]

The shape of the combustion chamber, not only controls flow, but also the CR. I've found a transfer area at a 12 degree angle provider good flow. But decreases CR. also the exit of the transfer area also has an affect on flow. For street I use an 8 degree angle for the transfer area and a 60 deg exit. I like to use Offy head for shaping the chamber because they are thicker than the Edelbrock heads.. Some consider flow behind the valve,but i couldn't prove that. I mill the area over the valve at a 5 degree angle. this removes less material to keep the CR as high as possible. With .045" piston to head clearance I can get 8.5 CR in a 276 ci engine. The next best thing would be to remove the spark plug to the center of the transfer area. This will shorten the flame front. Less detonation with a low grad fuel. Now that we're getting a new block, we might want to take another look at Flat 32's heads.

[Tod]

Let's just relax as the tooling slowly moves along. I have more work than I've ever had and no help, so it will be longer than usual to get to the foundry to make the first one.


I don't mind reading discussions about the possibilities but don't expect imminent testing.


Tod