Should I rebuild my Quadrajet or get a new carburetor?

I'm glad I was able to keep the Q-Jet also!

The plate is apparently there to block exhaust fumes from getting into the carburetor. I'm not sure why there were holes in the intake manifold in the first place, if they subsequently plugged them with a plate. A friend of mine has a '63 Riviera that also has this plate. Not sure if/when they stopped using it on that engine though.

I'll double check with my mechanic on what type of silicone he used. I'm sure he used high temp as he's been in the business for over 20 years. Someone else replied to me on the ROA list and said that he ran his engine like this (no plate, with the holes plugged) for years with no problems.

Dan

 

Exhaust crossover in manifold

:Smarty:
Buicks in the 60's ran exhaust through the intake to heat the carb from below. It was there to combat "carb icing". With cooler, damp outside air conditions like foggy mornings, you could get ice build up around the throttle plates. The sudden reduction in air pressure (vacuum) and vaporization of fuel at the plates causes a reduction in temperature -- enough to form ice which could keep the plates from closing or plug the idle and transfer slots. A thermostatic bi-metal spring controlled valve closes off one exhaust manifold at the exhaust pipe and forces the hot gas up through the intake and over to the other exhaust manifold. This heats the underside of the carb right at the area where icing occurs. The valve opens when the engine gets hot enough.

The steel plate was needed because the hot corrosive exhaust gas was hell on the under side of the aluminum throttle body section of the carb. The steel plate forms the roof of the passage. My '65 401 has a Rochester 4GC with a cast iron throttle body, and doesn't need the plate. Carter AFB equipped engines had the plate, as did the later Q-jets (both have aluminum thro. bodies). I believe they stopped using this system in '69 or '70. It is totally separate from the choke system.

To answer your question, you should be OK by blocking off that passage in the intake manifold. Warm up on cold mornings will take a little longer, but lots of people do it without any problems. On nailhead intakes the passage size is real close to the tap drill size for a 1/8-27 NPT tapered pipe tap. The best way to plug it is to run a tap in both sides of the passage and install pipe plugs. I'm not familiar with the later engines.

I am a little leery that any hi-temp silicone would be able to handle the heat, but it might work because you are stopping the flow. Most silicone doesn't like being immersed in gasoline either. Then again, it might hold up fine for years.

Hope this helps, but like some one on this board says in their signature -- No refunds on bad answers. :grin:

 

Thanks for the detailed info Kevin! I knew there had to be a reason for the holes. I'm in Texas, so I don't have to worry about cold mornings to much. Hopefully the silicone will last for a long time also.

Dan