I'm looking for recommendations for the best rebuild kit for a 6340S Thermoquad for my 1973 Cuda 340 automatic CA car. I scanned through
@Vaanth tutorial, but I didn't see a particular recommendation. Any feedback is appreciated.
Thanks,
Kansan
I actually looked at them on the K4270 kit. It says it is for the 6340S and the 6340SA. Do you know the difference between the 6340S and the 6340SA, although they are both listed as compatible? I think the brass float upgrades are a solid choice, not sure about the others. The 13 100% reviews are comforting as well....
www.carburetor-parts.com
Thanks,
Kansan
My Thermo-Quad Guide does not make specific kit brand recommendations, as it is a reference guide. Some of the brands and kits listed for reference are not available new any longer, but still found as NOS. Some of the companies are gone too.
The stuff from Mike's Carburetor Parts appears to be of good quality, which is also supported by the testimony of others, but I've never used any of this brand myself. Actually, I have not purchased any kits made in the last decade+. I rebuilt some of my Thermo-Quads over 20 years ago using kits from then and earlier which I had stocked up. Since then, I still pick up an NOS kit on occasion. I have 20+ kits, of different brands, on the shelf.
Of the kits I have used, my preferred top three brands, mostly in order, are: Chrysler, Carter, then Hygrade (Standard). The spacer gasket that is in the Hygrade kit, and some Carter kits, is preferred. In general, for ready availability, my choice was Hygrade. The Hygrade kit is still made by Standard Motor Products (SMP), and the kit for your 6340S is 657C, but not having purchased one made in recent years, I don't know if they are the same quality or content any more. Looking at a picture of the contents in a listing, it looks like they may have changed the spacer gasket.
Most of the name brand kits listed in the guide were decent to excellent. Chrysler kits are scarce and Carter kits are not common. Following the Chrysler, Carter, and Hygrade brands, Motorcraft and ACDelco are actually good kits. On the lower end of the scale was Sorensen. While okay, they made some undesirable changes in their kits, especially in some Holley kits. Some other brands could be re-boxed Sorensen.
Older NOS kits can have brittle paper gaskets, and sometimes shrunken rubber parts. So, although they may have been of better quality than some newer offerings, age can get to some. Of the modern brands, Walker seems to be a big player now. They have been around, but seem more pronounced now. Not knowing specifics of new stuff quality and content first hand, I might lean toward Mike's kits now if I needed a new one and could not find or use an NOS kit.
Chrysler offered three levels of repair kits, which are generally more application specific than aftermarket kits. The kit levels are major, minor, and gasket. Major kits had a lot of hard parts including jets and metering rods. Minor kits were similar to aftermarket repair kits. The gasket kits are just gaskets without any rubber or hard parts.
For the 6340S, the Chrysler kits were as follows: Major kit = 3744765 Minor kit = 3744758 Gasket kit = 3744757.
The four digits of the Thermo-Quad model number is followed by an 'S' suffix, such as 6340S. The "S" denotes an assembly rather than just a part like the float, which has its own part number. Carter used this assembly lettering on other types of carburetors too. Some numbers might have an "SA" suffix, which denotes a production change in the model without a change to base number. This change appends an "A" to the "S", such as 6340SA. The specific change was not usually documented externally to Carter and typically made no difference in settings, or general parts replacement. It could be something simple like an enlarged air bleed for an emissions improvement. Subsequent production changes were appended "B", "C", etc. although seeing these is uncommon. "S" and "SA" models are interchangeable. A more substantial change dictated a model change and new number. The change may occur on Chrysler's production carburetors or later in service carburetors. For changes that were enough to become a new model during Chrysler production resulted in a Technical Service Bulletin (TSB) such as 14-05-74D, but the suffix change from "S" to "SA" would not trigger a TSB.