Carburetor replacement

[mickn]

I have the original Rochester 4MV carb on my 73 350 L48. Does anyone know if there is a direct replacement carb for this that will just bolt on and work without the need for anything more major?

 

[Emc]

Is your carburetor an OE with a divorce choke, I have 9 fully rebuilt carbs, Rochester and holley

 

[mickn]

I'm afraid I have very little mechanical knowledge and couldn't say if it's an OE with a divorce choke, all I know is it's the original carb on a 1973 350 L48. The Haynes manual tells me it's a Rochester 4MV. I will try and ask the mechanic I use if he knows.

 

[Emc]

I'm afraid I have very little mechanical knowledge and couldn't say if it's an OE with a divorce choke, all I know is it's the original carb on a 1973 350 L48. The Haynes manual tells me it's a Rochester 4MV. I will try and ask the mechanic I use if he knows.

On the RH side there should be a coil spring in a case bolted to the intake, I have 3 rochesters with better electric chokes, these will fit but will require a ignition feed.you can give me a call 01283 219420

 

[Grahamred70]

I fitted a Brawler to my 1970 350 and it worked great straight out of the box just needed to set the idle mixture etc. think it's a 670CFM so only a little larger than the 600CFM that was on it when it came to me which was a Holley that was a bad match to the manifold causing an air leak, took a while to track that down!

Graham

 

[MilkyNoSugar]

I have a 454 big block, so not quite the same starting point and more challenges with clearance to the bonnet to worry about.

I am in the process of having a Holley Double Pumper carb fitted and tuned, along with a GM LS6 aluminium air intake manifold and new air filter, replacing the original cast iron intake, Rochester quadrajet carb and twin snorkel air filter. Paul at Lincolnshire Corvette is working on this for me and is doing a great job - really happy with the progress being made and work done.

My original carb had a built-in choke mechanism, and the new carb needs either a manual choke cable or an electronic choke controller, so not a simple direct replacement. There are also potential issues with the fuel pipe to overcome and clearance issues for the throttle linkage and filter housing from what I have read.

So far the differences in performance are very good and worth every penny, and I expect there is still some optimisation to be had here when the car goes back for the final bits of work.

EMC(Gavin) is also a bit of a legend and would definitely be able to advise on how simple the change is likely to be. I would strongly recommend you take his offer of a call up.

 

[Roscobbc]

One could argue the necessity to have a carb with choke (heat stove operated or electric) - a Holley double pumper is a performance oriented carb will be generally run a little richer on idle and intermediate circuits than either a period stock carb or later generic vacuum secondary carb. Being as you have two accelerator pumps normal procedure will be to run the engine over for a few seconds untill oil pressure shows - then pump the gas pedal two or three times and it should fire right up and hopefully hold a low idle during summer (perhaps run for a few minutes in winter) - it may have a tendency to stall when (if auto) selecting drive untill a little warmer.
If you're having carb/air cleaner clearance to underside of hood issues.......you can use an air filter with a thinner element and replace solid air clear lid with a K & N Air Filter Top.........like this

 

[Forrest Gump]

Same here - never felt a choke was necessary on my double-pumper equipped car. I’ve got a manual gearbox so I can just use a few more revs for the first pull-away. I guess an auto might not be so happy though.

 

[Mad4slalom]

Same here - never felt a choke was necessary on my double-pumper equipped car. I’ve got a manual gearbox so I can just use a few more revs for the first pull-away. I guess an auto might not be so happy though.

Same here, 650 double pumper carb with no choke. As forest says, wind her over not touching throttle to get pressure up then three or four pumps and fires perfectly.