I'm trying to round up enough parts for the rebuild of my 1970 440 Six pack carbs.

All of the throttle plates have holes drilled in them. From what I've seen, the center carb should have no holes drilled in the plates and the outboard carbs had holes drilled in them. My question is what size were the holes in the outboard carb throttle plates originally? Mine are at 3/32".

Since I'm building a milder motor with a hydraulic roller cam with 224/230 duration at .050" versus the previous 260 duration at .050" solid lifer cam that was in it previously, I want to get the carbs back to a more stock baseline and then go from there.

Check this out
http://www.moparts.org/Tech/Archive/fuel/7.html

I didn't see anything there about the throttle plate hole sizing.

A #226 throttle plate was used in early front and rear carburetors. These had a tendency to stick and a Chrysler Technical Bulletin was issued to change to a #199 plate after date code 3149. I got New Holley plates (p/n 9R199V) from Holley Technical Support for my carbs.
The hole size in the plates is very dependent on the engine specs (CR, cam etc). You want the center carb plates to be just uncovering the transfer slot at idle. This will give you adjustability on the idle mixture screws.
It is a real trial and error to get it right because you have to remove the center carb to see where the plates are positioned.
Jim
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And here it is if not too small to read.

We need a tech archive on what everything stock should measure. FWIW, my stock 1970 throttle plates have .078 front and rear holes, .080 on the center. On an engine with a 292 duration cam it needs bigger holes to get the center carb shut where it should be, been working on that .002 at a time.

I'm aware of the transfer slot/bypass hole size/cam/compression ratio, etc. relationship. What I'm trying to accomplish is to get the carbs back to somewhere close to the original baseline as far as the holes in the throttle plates are concerned. I imagine the holes in my outboard carb throttle plates have been opened up, I was wondering how much.

Did those #199 throttle plates come from Holley with a bypass hole drilled? Do you know what size they were? Mine have the #226 plates installed so I'll probably replace them while the carbs are apart.

That's the info I was looking for. Thanks. Some of the pics I've seen it appears there were no holes drilled in the center carb throttle plates.

The 226 plate hole diameter is 0.076", could be 0.078, but that drill does not quit fit in my plates. Close enough either way.

Note that they are drilled perpendicular to the base with the throttle in the closed position, not perpendicular the plate itself.

A little more.

[/quote]

I'm aware of the transfer slot/bypass hole size/cam/compression ratio, etc. relationship. What I'm trying to accomplish is to get the carbs back to somewhere close to the original baseline as far as the holes in the throttle plates are concerned. I imagine the holes in my outboard carb throttle plates have been opened up, I was wondering how much.

Did those #199 throttle plates come from Holley with a bypass hole drilled? Do you know what size they were? Mine have the #226 plates installed so I'll probably replace them while the carbs are apart.
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The 199 plates had no holes. I drilled them 5/64" (0.078") on an angle

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All of my 1970 and up outboard carbs, 4 sets, have .078 holes, centers about .002 bigger. I do not have any 69 carbs. I am up to .081 on mine and need more as the dist port has vacuum at idle. It will idle at 750 with no vacuum, but I want it at about 950, so about 10-20% more drill area, probably about .085-.090, need to do some r2 x pie math. It would not suprise me if replacement plates are blank. I think .075 would be a safe start.