The Stovebolt Site Forums The Parking Lot Big Bolts 283 2 bbl is a dog when cold

The original 283 in my 58 Spartan 80 was replaced in the 1970s by a former owner. He replaced it with a 1964 283 from a full size car with its (rebuilt) 2 bbl Rochester carb. Runs great, like a sewing machine, but when I head out the driveway, when it is still cool but not cold, with choke off, it sputters and dies, requiring lots of clutch nursing. Once fully warmed up, it is OK. Should I be looking at a 4 bbl as was original.....or maybe I need to keep the choke on halfway for a while longer? I'm starting out in 2nd, not granny gear (New Process 5-spd). I'm not carrying a load. As usual, I am seeking your advice....thanks!

Forgot to add: I'm trying to start out in hi range (2 spd rear), but seems i should be able to without a loaded truck.

That is EXACTLY what a choke is for, Use it. It is also what a heat riser is for. I.E. cold air. Be sure your air cleaner is BIG and Clean.

Bartamos, thanks! I'll try using the choke more liberally and I'm thinking more about the air cleaner (it's on the smaller side and is not the OEM)

Make sure the heat riser valve is working properly, and you've got the right gasket under the carburetor. That Rochester 2 barrel has an exhaust passage built into the cast iron throttle body, and if you don't have the right base gasket it keeps the exhaust gas from heating the carb base and the intake manifold properly. The heat riser passages in the intake manifold are also bad about getting plugged up with carbon and restricting or shutting off the heat.
Jerry

Jerry, Thanks for the added insight....that is something else for me to take a closer look at....I think the gasket is right as i remember the punch-outs in it, but it would be easy for me to check. I will also check the heat riser for free movement. I don't know how to clean out the passages or if can be done with manifold installed, but will check my manual or wait for your further guidance....thanks!!

The passages often clog right at the carb base gasket and can be drilled out. They are only about a half inch deep and then open into bigger passages below that rarely clog. You should be able to blow air in them and hear it at the tailpipe.

The bi-metal spring on the heat riser should lift the weight and close the passage when the engine is cold. It should lower the weight when the engine warms up.

I used to use a short piece of speedometer cable chucked into a variable-speed drill motor to snake out those passageways- - - -sort of a mini roto-rooter. The carbon deposits just fall into the exhaust ports and get blown into the muffler on the next engine start.
Jerry

I'll add that starting out in 2nd gear-Low while the engine is cold will allow it to warm up faster and help prevent the stumbling.

I drive all of my 2-speeds the same way...start in 2nd gear-low and work it up to high gear-low and then flip it into High gear-High range.

Mike B

My 283 did not have a heat riser from the factory, check the shop manual - some models have it, some don't. Mine drives the same way, just takes time for the intake and carb to warm up. If the engine loads up with the choke in use then you need to adjust the fast idle to compensate for added fuel when cold.

Thanks for all the added pointers..... I will check/clean all the parts and adjustments....and maybe 'adjust' my driving methods also!