Jeff Kauffman Responds: You could rebuild the carb and get a little better performance and mileage out of it. But, it's really not going to pick up much. If you install a nice Holley 750 Double Pumper carb, that will help in the performance range big time (a 15-20hp gain), but you won't get any mileage increase from it.
The better setup to balance performance and mileage would be to go with a good rebuilt Q-jet like a Cliff's Q-jet carb, (740) 397-2921. This will get you the best mileage because of the smaller primaries on the carb, and the performance will be there because of the large secondaries. It should be just about the same in performance as the 750 DP carb once it's set up correctly.
You also may see a mileage-and probably a performance-increase if you drop the rearend gears to something like 3.42. The torque produced by your 455 doesn't need a numerically high gear to get your Bird moving.
Unexplained Brake Drums And Firewall Markings - I have been a subscriber to your magazine since 1988, and I still love it. I currently own eight Pontiacs (seven convertibles) and one Corvette. My most recent purchase was a '68 GTO convertible. It does not have the original motor, and some options seem to be added. I am in the middle of getting the PHS docs for it to see what it's all about.
I have two questions about this car. First, it has front-disc (four-piston) brakes and rear drums. The rear drums are 2.5 inches instead of the standard 2 inches. No one was able to find a listing for oversized rear drums, so we had to use front drums from a four-wheel manual drum GTO. Does this sound right?
Also, when I was detailing the engine compartment, I noticed the remains of what appeared to be a wax pencil marking on the firewall-"R-26." Is there any way of finding out what that symbol means?
I really enjoy your magazine, and other than my Vette, Pontiacs are my life. I have '67 and '68 convertible Firebirds, a '92 convertible T/A, '65, '68, and '70 convertible GTOs, and a '70 convertible LeMans. Four of the cars are done, and the others are in various stages of restoration. I will be sending some pictures in the future. Rich Reidenbaker Shamong, NJ
Quint Stires Responds: Sounds like you have a great collection of musclecars. Regarding the brake drums, the restoration houses that advertise in HPP list the 9.5x2.5-inch drums as the standard size for the rear. The front brake drum is almost 3 inches wide. I'm not sure what was happening at the parts stores-perhaps they were looking up the wrong application.
I can only give it my best guess as to the grease-pencil marks in the firewall. There isn't any definitive answer for why line workers wrote what they wrote, but my best guess would be that the "R" is for the color code "Solar Red." The "2" is the fact that it is a GTO (part of 242), and the "6" is the first digit of the convertible code "67." I feel it was marked so the employees down the line would be aware that this was a red Goat convertible. This is only my opinion. If any readers can help shed light on this mystery, please contact me at Qstires@yahoo.com.