Phenolic Spacer Installation

[Jon S]

I read John Washburn’s Article in The Self Starter - The Skinny on Shims and found it very interesting and informative. I believe I have installed the phenolic spacer right side down and upside down over the years never knowing which side should face up. The good news is the car ran beautifully both ways, so I never gave it another thought. I always had the gasket, insulator, gasket tin plate sequence correct and it didn’t seem to matter how the insulator faced. Well, now I know. I’m curious how I last installed the insulator, but since the car runs so well I do not plan on taking the carburetor off to see. I could never understand why the insulator had this cutout path but assumed wedged between two gaskets, it made no difference how it was installed. Maybe John can shed some light on that. Just curious. I know next time I rebuild the carburetor I will make sure the heart shaped groove is facing up. Great article!

[Clewisiii]

Thank you for bringing this up.  I was trying to figure out how to install my gaskets and insulator.  I had not read the self starter yet.  As he says the 61 shop manual does not talk about it.  Now i just need to figure out if it is the same gasket on either side of the insulator. and I have a Rochester so i do not believe there was a shim.

[Jason Edge]

John's article stated "I then went through the Cadillac Shop Manuals from 1960 to 1966. I could not find a single reference on the installation of the carburetor gaskets, insulator or shim for the Carter AFB Carburetor" which is not correct, at least for 1963 and 1964.  The 1963 and 1964 shop manuals do include instruction for gasket, insulator and shim installation. In the 1963 manual it is on page 10-11, Section 20.b. Carburetor Removal & Installation, and in 1964 it is on page 8-17, section 27.b Carburetor & Installation.  The information regarding placement of gasket, insulator and shim are the same 1963 to 1964. (See 1st attachment). Also, by 1963/64 the intake to carb insulator was stamped "TOP" in large print on the top side. (see 2nd attachment).

To dig a bit deeper regarding the shim, Spoil Ports were added to the Carter Carbs so they would not idle correctly if the shim was left off. According to the the Oct. 1962 Serviceman Bulletin, page 50 (see 3rd attachment), two holes were drilled into the carburetor to prevent correct idling without the shim. The note indicates the shim is used to prevent corrosion and damage to bottom of the carburetor.  (see spoil ports at bottom of Carter AFB in 4th attachment) While I do not have anything in print stating as such, it is obvious the softer aluminum base of the Carter AFB was much more susceptible to the corrosive nature of the exhaust gases from the center intake manifold exhaust channel, than the steel base of the Rochester 4GC. At least that is my best guess!

[Jon S]

Jason - Very interesting. Thank you.