As to the base gaskets . . . when I upgraded the '66 Newport to a Holley 2210 2bbl, the carb came from Holley with a thin base gasket, which I used and was already under the prior OEM Stromberg WW3 2bbl. Every few weeks, I'd have to re-torque the nuts holding the carb to the manifold. The idle would get just a hair rougher, which re-tightening the nuts fixed. Got to where I carried a 12pt wrench of the correct size under the front seat!
I got tired or that and went to the local Chry dealer parts dept and got a correct 1970+ Holley 2210 base gasket/insulator for it. After one re-torque (after the first few hot-cold cycles), that was the last time i needed the wrench.
My '70 D43N was bought used at 83K miles. Unmolested. It had the thick gasket under the AVS. Had some hot re-start issues, as normal. I looked at various different carb base gaskets for it. I settled on the Mr. Gasket aluminum/fiber gasket stack. As easy and careful as I was to do the torque in sequence and such, that ONE "just a bit too much compression one corner" cracked the base plate by the vac advance nipple. Got a new AVS 4734S as a result AND used the thick insulator gasket with the metal sleeve in it (to prevent such uneven compression of the gasket).
I also gave up on using a vac gauge to set mixture back in the late 1960s. I like the precision of a dwell tach much better. Using that device, I can tell when the mixture screws are leaned enough to get a 20rpm drop and then put each one back where it was.
I also stopped worrying about not getting 18+" of Hg manifold vac at idle, too. At the 1200' elevation I'm at, that would mean 17" Hg, but 16 was more doable so that was that. I checked EVERYTHING to make sure it was to factory specs, too! On a couple of our vehicles at the time.
As to the thickness of the carb base gasket's thickness (thicker in place of thinner), there are TWO things at play here. One is that with time and use, the choke thermostats will tighten a bit, making the choke come off later than sooner, so I usually re-set mine to "1 Notch leaner" than factory specs. Easy to do! As to the length of the choke rod to the choke plate, there is a slight bend in the linkage that can be flattened slightly (with a pair of pliers) to lengthen the rod if desired. Again, easy to do. Just like I normally also decrease the "V" in the choke pull-off link, to pull the choke a bit farther open initially.
These two tweaks effectively lean the choke operation a bit. I also play with the fast idle screw such that the last notch does not increase hot base idle any at all. I like the choke to be open enough for low idle speed after two blocks of driving after backing out of the driveway. NGK V-Power plugs help in this quest, with their gap design that exposes more of the spark kernel to the air/fuel mix.
When I upgraded the '67 Newport 383/325 (factory) to a 9801 TQuad and Torker 383, I again used the supplied thin base gasket. Car drove good, but did not have much better WOT performance than the OEM AFB supplied. But with the Torker, I was looking more for better mpg wiht more-even fuel distribution (which was what the Tarantula and Torker intakes were known for. That was a let-down, too. Until . . . I put the OEM Chrysler thick base gasket under the TQuad. WOT felt "happier", so I left it at thatl I had read about there being a relationship between the bottom of the carb and the bottom of the intake plenum. Too close, too tight of a corner for the mixture to make. What I felt seem to validate that. BTAIM
With the Torker and TQ, the car ran well, but not outstandingly better than the OEM AFB or a '70 383 OEM used Holley 4160. When I start driving it again, it'll have a AVS2 (purchased a few years ago) on it.
Going from the OEM AFB to the TQuad, I DID need to get the throttle rod extender from Edelbrock. I adjusted the rod per spec, then added two more turns preload (as I had done to the '66 Newport 383 2bbl) to raise the part-throttle shift points a few mph. The primaries on the spreadbore were that much farther forward on the manifold than the AFB/AVS was. I also got a spark throttle rod from a 383 2bbl in the local salvage yard.
These are MY experiences since 1970. No more, no less. If anybody might choose to follow/emulate them, YOUR judgement call. YMMV
Have fun!
CBODY67
