Which carb gasket do i use ??

I don't see this jeep being driven in cold weather. ( no top ) if I go that route won't the thick gasket plug the holes ? And do I eliminate the heat riser then ?

 

On my 3B Jeep with a transplanted V-6 I run without the heat riser and do not have any issues. I just let it warm up a bit and back the choke off before I drive it...it does not have a top either and I do not drive it in the winter or really anything much below 60*F or so. The thick gasket should somewhat plug off the holes but there can still be a corrosive effect to the carb studs / bolts so plugging off the holes completely still is desirable. If you thread the holes and put pipe plugs in it can always be reversed later if you wanted to for some reason.
Oz

 

It's not exhaust gas - it's hot air. It's a choke stove. Bringing exhaust gas into the carburetor base would be nutty. The carburetor body is a zinc alloy and would not last for a year exposed to exhaust gas. And the thin gaskets used to seal the base of the carburetor would never stand up to exhaust pressure. It's just hot air. Sealing the holes with a gasket will be fine.

If it works, leave the heat riser alone. The heat riser will still warm your intake manifold. Under the control of the heat riser flap, exhaust gas goes through an internal passage in the manifold and warms the manifold. There is no mixing of exhaust gas with the intake air. The warm manifold keeps gasoline from condensing on the cold inner surfaces of the manifold, and makes the engine run better when it's cold.

 

Tim, I believe we are talking about 2 different things. The holes in the manifold are indeed exhaust gas passageways, that's why they carbon up and are corrosive to the manifold. I am familiar with the heat stove type of heat riser which I believe you are referring to but when the OP mentions heat riser I picture in my minds eye the butterfly valve that is attached to the outlet of the right hand exhaust manifold between the manifold and the exhaust pipe.



When the engine is cold this valve will pretty much closed causing exhaust gases to travel through the passages in the intake manifold, under the carburetor out to the other side thereby heating the carburetor base. This is the "heat riser" that I am referring to. The carburetor base is iron. The exhaust gases are not mixing with the intake air...they are just passing under the iron base of the carburetor to heat it



Here is a bottom view of a Rochester 2 bbl. and you can see the area which the exhaust gases will run under the iron base and also come in contact with 2 of the studs / bolts.



Oz

 

Well I am not to knowledgeable about metals but the 2G type carbs have a cast iron type throttle base and withstands the heated exhaust gas that is ported through it. The exhaust gasses will carbon up the holes making them non useful so I no longer un-plug them. I do use the gasket on the far right of the picture but using the one that closes the heat circuit will not compromise the system. The use of copper coat has worked for me as well.

(I see someone beat me to the base material)

 

I didn't realize the carb gasket would be the hard part of the rebuild lol, so basically if i want to stay factory correct go with the thin gasket on the right and leave the heat riser (which took me a month to find on ebay in good condition ) or to improve from factory use the thick gasket or tabbed one without the heat riser ? I will clean up the manifold a bit with a block of steel and some sand paper.

 

I've been running the 225 since 1969 and have always used the thin gasket. Never worried about it burning out. It was design that way. Run it.

 

Oz is correct, that is in fact an exhaust passage.
The correct carburetor base gasket has fiber sandwich / metal much like an exhaust manifold gasket. That way it can stand up to the heat.

 

My local carb rebuild shop recommended plugging the ports in the intake. There reasoning is that it can cause overheating of the fuel and accelerator pump problems. They say they do it on most of the older cars that come through their shop.

 

Opinions seem to be mixed here leaning more towards the thick gasket. I took the carb to a mechanic friend and showed him photos of the manifold and he agreed to use the thick gasket, he said no need to plug the holes as the gasket will do that, so that's the route I took. If its not right and i have issues i will just have to address it later. Now i need to decide if i want to leave the heat riser on . He said if it works just leave it on so it looks factory. (Since I'm anal about that ) Thanks for the input

 

The motor is looking good, its cool that you actually have the I.D. tag for the carb.
The thick gasket will block the exhaust gases from the bottom of the carb but they will still come in contact with 2 of the 4 bolts holding the carb to the intake. I would simply coat the bolt threads with anti-seize compound so they can be removed easily at a later time.
Oz

 

I would plug the holes if running that gasket...it isn't designed for exhaust heat.
It may take awhile because it's very thick, but it will burn through.