Transfer slots.

[73ss]

I have a 17080212 carb that I am planning to use. It does not have a attachment for the TV cable on an overdrive trans. I was hoping to use the base plate from a 17084228. It has the correct attachment for the overdrive and also has ported vacuum to where the 17080212 base plate does not.
I notice the transfer slots are a good 1/32 or so longer on the 4228 base plate. If I swap base plates will the longer transfer slots cause major tuning headaches? 

[Kenth]

The only thing i´ve noticed with the longer slots is i don´t need the mixture screws out as far as they need to be with the shorter slots.
On the other hand, you can always swap the throttle shafts.

[Cliff Ruggles]

It is ALWAYS best to keep the three parts from any Quadrajet together vs swapping in a part from another unit.  The transfer slots can not only vary in length they can vary in location.  They are a key player in off idle smoothness and transition to the main system.  I would for sure swap out the throttle shafts vs the complete baseplate........

[quadrajam]

I tried swapping a base plate once an it didnt work very well. surging idle, cant set idle etc.
It was omly slightly different. Like Cliff said the shaft swap would be the easiest way out.
Then you could go ahead and rebush the throttle shaft bores.
That 84228 carb is a nice carb too if you convert it to front pull-off. I havs several
84226 in my collection that run great. Probably very similar. Good Luck.

[73ss]

Thanks for replies. What if you wanted to run ported vacuum for the distributor on one of these truck carbs? Did the factory run full vacuum for the distributor on these carbs? Most all of the truck carbs I come across have the full, non ported or timed vacuum port.

[Cliff Ruggles]

If you want to use ported vacuum to the distributor and the baseplate isn't set up that way it can be added.  Sometimes I use the port that supplies vacuum to the EGR simply by blocking the bleed-off slot beside the source location. 

For baseplates already set up for manifold vacuum to the vacuum port just to the left of the fuel filter housing (as viewed from the front) you can drill a very precisely located hole just above the throttle plates so you get full manifold vacuum right off idle.  This is a little more difficult but I'm pretty good at it these days.  The lower slot must be blocked so you only get vacuum just off idle and no vacuum at  idle........

[Mr.Pontiac]

I have a real nice shaft for sale for tv cable if needed, contact me rbudney@comcast.net