Intake surfacing

[3twinridges]

I know the heads are routinely surfaced on a new flathead build. Do you guys also have the intake surfaced? Is that a common practice or recommended?

JB

[Kube]

Originally Posted by 3twinridges

I know the heads are routinely surfaced on a new flathead build. Do you guys also have the intake surfaced? Is that a common practice or recommended?

JB

I'd yet to find that necessary. I do check mine with a straight edge in all directions. To date (after 48+/-) years, not one time did I find an intake that required finishing.

[OldGold360]

It’s probably not necessary but it also doesn’t hurt. I usually do the intakes as well as the heads, but I also have an abrasive sander specifically made for performing this task, which makes it easy.

[tubman]

Never did it; never had a problem.

Just lucky, I guess.

[19Fordy]

3twinridges: What purpose do the 2 recessed groves serve? Never saw that before.

[Flathead]

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Matches up to the vac. wiper port on an original intake.

[V8COOPMAN]

Originally Posted by 19Fordy

3twinridges: What purpose do the 2 recessed groves serve? Never saw that before.

Jim.... I don't believe 8BA manifolds have this feature. On the earlier engines, you'll note the DOUBLE holes on driver side of manifold. BOTTOM hole is vacuum. There is this one toward front, and another pair of holes toward rear. Note how these holes correspond with slot between cylinders in bottom picture for vacuum source.

Coop

[Flathead Fever]

You can set it on the block without the gasket and check for warpage with a feeler gauge or use a machinist straight edge. Heads, block... do not need to be surfaced just to make them look pretty every rebuild. If they are within specs, they are fine. You could warp a modern V8 aluminum intake manifold with the angled sides by not torquing them evenly, but I don't think you could hurt that flat, flathead intake. Never say never but you would have to really try to warp it. There is no compression pressure, no coolant pressure that would cause a leak, just intake vacuum. Even if it was off a few thousands, a part will flex that much in that amount of length when its tightened down. We replaced head gasket all of the time that had just a few thousandths warpage on the heads and the gasket lasted as long as the originals had. My neighbor went through ten blocks to get a good flathead block. He took it to the machine shop to have it decked so it would look pretty. It did not need it. They chucked it up and walked away and it slipped in the holding fixture. When they came back it had cut from hardly anything on the one end to cutting a half-inch off the other side. He looked for another block and took it to a different machine shop. They dropped it off a forklift and broke it.

[Brian]

So, after all that rigmarole, I suppose he bought a SBC to put in it!???
Actually, I once bought off of eBay an Offy twin carb manifold, and it was warped; it had a twist in it; you'd place it on top of the block and you could rock it!

[Ol' Ron]

I try to mill the heads to give .045/.050" piston to head clearance. This improves combustion, amonng other things. Worth the effort!
Gramps