17085213 transfer slot

[novadude]

I have one of these carbs, and it seems the transfer slot is ~7/32".  I have another carb where the transfer slot is only 5/32".  Did these vary much on different carb models?  Any "best" length?

On the 17085213 with the 7/32 slot, it seems that .050-.060" of the transfer slot is exposed with the throttle completely closed.  More than the unit with the 5/32 slot (~0.030-.040").  This carb still has the hardened plugs in front of the idle screws, so it is a "virgin" unit. 

Any issues using the carb with the longer transfer slot?  Any change in idle calibration for these units, or just use the standard "recipes"?  Thanks in advance.

[Cliff Ruggles]

How much transfer slot is available is not a player with most builds, unless you get the idle tubes and idle down channels way too large for what you are doing.  At that point, there will be no control with the mixture screws as the engine will get plenty of idle fuel thru the transfer slots with the mixture screws completely seated....Cliff

[novadude]

Thanks.  I was worried that the longer transfer slot will kill MPGs.  Sounds like it's a non-issue.

[Cliff Ruggles]

No, but it will allow more fuel to the engine at idle and very low throttle openings, so it does add to the main system some.  The only problem it's really going to present, is when the carb would be set up for an engine with very little vacuum at idle speed, where it needs a lot of idle fuel to the mixture screws to be happy.  Quite a bit of idle fuel can flow thru a lot of exposed transfer slot, making idle tuning difficult if you have too much fuel available to them.

As mentioned earlier, this is seldom an issue.  Even when set up correctly, you may notice that the mixture screws can be fully seated and not kill out the engine, as it still gets some idle fuel past the exposed transfer slots.  As long as you can slow the engine down some with the mixture screws, or able to lean it out some, it's not an issue for that particular set-up.......Cliff