I do still need the measurement of the distributor shaft past the bottom of the gear if anyone has a distributor laying around!

That is true about the gear location and was my original plan. I can do a video and maybe post it here somehow and explain why I'm not doing it that way on this one. If you are using all Ford housings, moving the gear on the shaft is the way to do it. This Holley Distributor housing is much taller so instead of moving the gear on the shaft deeper into the engine, I'm going to re machine it to slide the entire distributor into the engine. Very common process in aftermarket builds with slip collar distributors. The only additional challenge I've found is the block hole size Y vs SBF. I have a SBF on the stand now I'll measure today and see what's up.

Still need that measurement for shaft protrusion through the gear if anyone has it.

The length of the shaft residing below the distributor gear is typically in the 1.000” range.  The hex hole in the bottom of the distributor shaft must be deep enough to prevent the ¼” hex oil pump drive shaft from bottoming out when the distributor is fully seated in the block.

The distributor holes in the production 1954-1967 FYB 239/256/272/292/312 blocks are all the same.  The diameter of the FYB distributor holes is ~1.500” which is also the same as all years 289/302 small block Ford engines.  Do not confuse the 351W distributors for the 289/302 engines as the 351W distributors are larger in diameter where they fit into the block.  There are some other major differences with the 351W distributors but that’s best saved for another conversation.

The depth of the distributor holes in the blocks is different between the FYB and SBF.  Those depths are measured at the point on the block where the distributor rests and to the pad in the block where the gear rests.  The FYB engines are ~5.0” to the distributor gear pad in the block while the measurement for the 289/302 engines is ~4.0”.  While the 289/302 distributor housings can be used in the FYB engines, the SBF shafts are too short and the gears are different.  Both use the ¼” oil pump drive though.

It’s extremely important that the distributor gear location on the shaft corresponds to the depth of the hole in the block.  If the distributor gear is too low on the shaft, then binding at the gear takes place and the distributor gear and cam gear wears out in a short period of time.  There is some leeway in the gear being too high but not much.  Under no circumstance should a gasket be used at the block under the distributor housing.  Using the OEM ‘O’ ring that’s on the SBF distributor housing on a Y-Block engine is not necessary but not a show stopper if being used anyhow.

Lorena, Texas (South of Waco)

Thanks Ted! I figured out the issue I was running into! As you describe, "SBF distributor" simply isn't specific enough, there are atleast 5 different version of shaft/gear/housing that I found this morning. I found the numbers on my Hyper Spark distributor and it's a 351w Roller cam variant with too large of a housing and 5/16" hex drive. I did score a hex drive FYB distributor this morning though! Back to drawing board to figure out the easiest way to get it fit!