Downeaster64

I've got a 400 block that came out of an automatic transmission vehicle. It doesn't have the drilled and tapped hole for the clutch cross shaft pivot ball. Can the block be drilled and tapped for the pivot ball?

Avispa

Why risk it? GM makes a bolt-on adapter for newer blocks that can't be drilled for a pivot ball. I'll try to find the part number.

MikeM

If the cast embossment is there, I see no reason the hole can't be drilled and tapped. 400 engines were used with manual transmissions but I don't recall how the clutch linkage was set up on various models.

Robert61

Yes it can be drilled and tapped. You may need to anyway if using a bracket.

Avispa

All Chevrolet cars other than Corvettes had the clutch pivot ball threaded into a hole on a boss just ahead of the bellhousing flange, above the oil filter. Corvettes have the hole about 6 inches forward of that on the outside of the water jacket part of the block. I'm sure the metal is there on a 400 for any other Chevy car, but not so sure about Vettes.

The bracket I mentioned is held on by two bellhousing bolts. It's for Gen V big blocks with no Corvette pivot ball boss.

Avispa

https://sdparts.com/i-24074894-sdpc-...nd-trucks.html

https://sdparts.com/i-24074895-sdpc-...corvettes.html

Found it. Here you go. The top link is for everything but Corvettes. The bottom link is for Vettes so you can see what I was talking about where the ball is located.

MikeM

Depending on application, SB's had, I believe, three different locations for that embossment. Some blocks had none, some had one, some had two.

I believe light trucks and Chevelle had a pivot ball bracket mounted on the bell housing. Whether or not that bracket you recommend will work might depend on which car line the OP is using.

MikeM

Looks like the brackets in that link will cover everything except '62-'67 Chevy II.

Downeaster64

This 1971 400 is being considered for my '64 Corvette. I just now looked at the 400 and the blank boss is above the oil filter about 1.5" forward of the block/bellhousing flange.

Pop Chevy

400 is a good engine , built right. I'm going to build one for my 60 and I never thought to look at the clutch boss.

MikeM

Like this? Which hole?

DZAUTO

I have built quite a few SB400s (have 5 of them in my family) since the early 70s. The last one was last year for my son's 73 Vette.
It is true that SOME 400s do not have the boss drilled/tapped for the ball stud--------------------------BUT, it is just TOO EASY to do it!!!
Although, do not drill/tap any deeper than necessary for the ball stud.
In addition to the boss for the ball stud, SOME first generation small blocks also do not have the 2 bosses on the right front side of the block drilled/tapped (these were ORIGINALLY for 55-57 Chevy front motor mounts and have continued to be cast onto all later SB blocks). These may need to be drilled/tapped for a PS pump bracket.
Last, SOME blocks (the last 400 I built) do not have the two holes on top on each side of the bell housing flange for attachment of the spark plug wiring bracket One of the two holes DOES NOT go through the flange. It is for the locating tab on the plug wire bracket. The other hole goes all the way through the flange and is tapped for 1/4-20 threads.

Here are undrilled bosses for the ball stud. Also, right next to the cast GM on top of the bell housing flange, there is a flat pad. That is where the holes need to be if the engine will have a spark plug wire bracket attached.



You can barely see those 2 holes below the head on this block.



Here is a better picture of those 2 holes, which have not been drilled on some blocks.



Here are the front bosses (not drilled on some blocks) after we drilled/tapped them for mounting the PS pump.

Avispa

The hole above the filter boss is for Chevlle/Camaro/full size. The front hole on the cylinder bank is for Corvette. Not saying 400 blocks don't have the front hole boss, just wasn't sure and the OP has a good option if not. Should have thought to ask DZ cuz he's done a few 400s for all of us to see.

DZAUTO

This is a 400 block. As can be seen, it does have both bosses. So feel free to drill away.

TexVette66

Can a 400 sbc be internaly balanced like a 327 or 350 sbc?

Robert61

Yes. If you run a steel crank with longer rods. The original cast crank had short rods and the counterweights were made smaller to clear. With a longer rod the counterweight can be bigger allowing for internally balancing.

Rusler John

DZAUTO

Engines which are NORMALLY externally balanced (such as SB400 or 454) can also be internally balanced by adding heavy metal (such as Malory weights) to the counter weights, as below..



Also, a NEUTRAL balance flywheel can be made into an EXternal balance flywheel simply by removing/drilling metal from one side to achieve a balanced engine.
I had that done to a neutral balance 153 teeth flywheel for a 383 that I built.

MikeM

I had a 153 tooth flywheel balanced by drilling a few months ago by drilling. Much, much cheaper than adding Mallory Metal. The engine is very smooth now. Previously, I used the engine with a 153 tooth automatic flywheel. Nothing there much to drill so you just add weight.

DZAUTO

That is exactly correct. Flexplates for auto trannys for an EXternal balance engine do NOT have weight removed. Weight is added by welding on additional metal, as on the 400 flexplate on the right below.