Drilling vac advance port

Hello all...ive been working on the hornet all day today, set base timing @ 8* BTDC in gear and vac advance plugged. It was at 4*, so im feeling good about the change.


Now...ive been running my advance from manifold vacuum and would like to change it to ported so that im not waayyy advanced at idle as i probably am now. Problem is advance port on the pass side of my carb is blocked. It looks like they casted a place for the hole to be drilled and fitting added, but thats it. The hole is a dead end. Maybe this particular carb was not supposed to run a vac advance?

Either way im thinking about drilling straight through to the carb throat and adding a fitting to the casted hole. Can anyone give some advice on how large the hole should be?

Actually its a stock 258, the carb is swapped however. I changed the yf to the bbd (not by choice =] )

Here is a pic of what ive got

2100s Are cheap, I gave a member 20.00 for mine,14 for a kit,
another 28 for the adapter,trans dapt ,
it runs great. U do have to do some fab work on the gas linkage,
I cut the arm of the carter and welded it to the 2100 .
This is what amc should have used!!!

amc401t10 wrote: 2100s Are cheap, I gave a member 20.00 for mine,14 for a kit, another 28 for the adapter,trans dapt , it runs great. U do have to do some fab work on the gas linkage, I cut the arm of the carter and welded it to the 2100 . This is what amc should have used!!!

Glad it worked out for you... I do recall them 2100 carbs do need a rebuild kit every 15 years or so. Both 304s had near empty bowls after sitting. Though once done right, they are good runners.

I rather use the more common sized venturi as you get a wee bit more performance and easy to find.

1.21 it is then...thx guys