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Tech Question
Kevin McKinney, Wichita, KS, 1977 Chrysler Brougham 400
Oh great GURU of Mopar Tech.
I know most folks have no respect for the the 5500 lbs cruisers, but she
only has 29,542 miles on her clock. And is very comfortable. To the point: I
replaced the Lean Burn with the standard ECU and distributor ect.
The ThermoQuad, as you know, has no port for the vacuum advance. This is
not a problem on anything else in my stable: 'Cuda, Chargers, and the 1966
3/4 ton Hemi Power Wagaon. But with the weight and sorry gas and the AC
running, to be good to her I think she needs the advance to work. If I took
the base plate of the the carb would it be possable to drill and press in a
cut off niple from a junk carb? If so what size bit/hole for the orfice, and
how deep...just to the passage? I can do the press fit thing on the nipple.
I read an artical some years ago I think it was Mopar Action where someone
sent their carb to a shop in California and had it done. I am a machinist/
tool maker ect., so tools and stuff wont be a problem. Can you give some
engineering info or specs, drawings, ideas? I haven't taken another carb
apart to have a look and see yet. This carb is like new 29,000 miles and the
shafts are tight ect. So I would like to keep it on there. If any one would
know how it would be you!
Thanks Kevin
Kevin, it can be done, but it is a bitch...it's a transfer slot, actually. Look at any non-ELB carb and you'll see.
Here's the near-zero-buck way to get around this: Take a length of super-small "hobby shop" copper tubing and rig it up so it points down either primary barrel, ending just barely above the rear edge of the throttle plate. You'll have to rig up mounting and probably notch the choke plate, but this is still way easier than modifying the throttle body. The top of this new tube = ported spark for vacuum advance cannister. To test, there should be zero vacuum at idle, and plenty when the throttle is held open slightly.
Now tune the vacuum advance. I'll bet that 8.2:1 mill can handle a total advance (initial + mech + max vac.) of almost 60 degrees at light throttle cruise. The more the better! The engine will last longer (no fuel wash, lots less carbon) and fuel economy will increase by a large amount -- possible as much as 30-50% (over having NO vac. advance). Help starve an oil baron!
Rick
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