i think i have a 350 in my 1971 lemans sport, how do I know for sure? Also, what would be the right size 4bbl to put on to replace the2bbl?
Check the block casting number. These are found on the driver's side of the engine, at the back of the head on the transmission mounting flange. You can use a mirror to see it.
http://outintheshop.com/faq/casting/castings2.html -- check casting number against this list.
there is also the engine it code on the front of the block just below the head on the passenger side . engine size should also be stamped on the side of the block near the motor mounts .
To address your 4 barrel question , if the engine is stock , leave it the way it is , you'll just spend more money in gas then anything else ! To put a 4 bbl you have to change the intake manifold . the carb doesn't need to be any bigger that a quadra jet , make sure it's made for that engine & not a chevy .
A prior owner already made the switch, I think the carb is bad and wasn't sure what is a correct size to replace with.
The 350 with automatic will run fine around 600-650 cfm with no other modifications. With 4 speed, cam, headers, and dual plane intake you can push 650-700.
A rochchesrter which is probably what you have now is the best carb for that engine , you can pick one up at a swap meet or on ebay make sure it a match for that engine . good luck
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