3269s AFB Questions

[Richard E.]

Two questions on the 3269s carburetor for a 62-340HP. 1) Anyone know what the primary & secondary jet #s and sizes are? I seem to be running rich, but don't want to change jets without knowing the baseline.

2) Any hints out there on heat reduction in the carb area to eliminate post-shutdown percolation? So far, all I've done is to install exhaust crossover block-off plates between the heads and aluminum intake manifold.

Any suggestions greatly appreciated. Thanx...Dick

[motorman]

Re: 3269s AFB Questions

pri. jet.104 sec jet .689 float level pri 5/16 sec 5/16 float drop 3/4 throttle bore pri 1 9/16 sec 1 11/16

[Joe L.]

Re: 3269s AFB Questions

Dick-----

With respect to your second question, if you've already blocked off the manifold heat crossover passage, you've taken the MAJOR step at reducing the carb heat problem that you've described. The only thing else that I might suggest is the use of a thick, insulating-type gasket. GM never offered such a gasket for AFB-equipped models, but aftermarket suppliers might.

In any event, what you've already done will accomplish about 90% of the heat reduction that you're going to get regardless of what else you do. By the way, I assume that when you eliminated the heat crossover that you also blocked open or eliminated your exhaust heat riser valve?

[Duke W.]

Re: 3269s AFB Questions

AFB small parts are available from Federal Mogul (On line catalog is at www.federalmogul.com). Your '62 340 will run hotter than my '63 340 at idle and low speed because is lacks vacuum advance. You could cool it down and get better econonmy if you installed a Delco single point distributor with a vacuum can. The best factory set up for this is the late '64 to '65 365/375 HP engines,which brought in all the centrifugal advance in by 2350 (engine) RPM. Vacuum advance specs are 0 deg.@4";16 deg.@8". Any Delco single point core distributor could be rebuilt and set up this way. If your '62 drives the tach off the generator (I can't remember) then a core should be dirt cheap, and you should be able to set it up so you can quickly swap back and forth with the original dual-point for NCRS events.

Duke