2 bbl to 4 bbl swap, suggestions please!

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smythge

65 with a BIG BLOCK
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Ok, I am considering swapping my small Carter 2 bbl on my 318 to a 4 bbl. on my 65 Dart. I have an edelbrock performer intake, edelbrock performer 600 cfm electric choke carb, all necessary gaskets, I am aware I will need to get a new throttle cable and mess with the kickdown linkage. The reason I want to make the swap is the carter leasks from the top, it is a pain to start I have to pump it like 20 times when cold then feather it to keep it running it has a mechanical choke, which is just wired open, and of course I'd like a little more power.

My question is, am I better off just getting the Carter rebuilt, going to another 2 bbl (suggestions welcomed) or making the switch to the 4 bbl. My concern with the switch to 4 bbl is the heads on the 318, everthing I have read says the heads have small ports and are not a good match for the 4 bbl, then I looked into switching the heads to a 360 but that lowers the compression. I don't want to waste all the time switching things to find it runs just as bad. Eventually I will be putting a 360 in it, but not for at least a year so I would like to be able to drive it this coming summer.
 
I did a 2bbl to 4bbl swap on my Dart's 318. I used an older Eddy SP2P manifold and a 500 cfm Carter AFB carb. I can't really give you good performance comparison because my original 2bbl carb was running very poorly. Plus, I put headers and dual exhaust on it at the same time. Maybe a good rebuild and tune-up would have helped it, who knows.

Anyway, the throttle response with the 4bbl and headers is great. Too bad my engine devoloped rod knock shortly after I made the swap. I would have liked to get a 1/4 mile timeslip out of it to see what it does.

My advice, if your engine is healthy, and you have a good exhaust system alrerady, then go ahead and swap on the 4bbl. I think your Performer manifold has the smaller size runners that match up to the 318 head ports. The RPM manifolds have larger runners that match the 340/360 heads.
 
One thing about the 318 and 273 is valve size. The 4bbl will give you a little more power, but if you can, pick up some 360 heads. Will lower the compression slightly, but the upgraded valves will give that little 318 some kick. I would also suggest headers. You'll see some improvement over the 2bbl.
Also, make sure you cover up the lifter area when cleaning the old gasket crud from the cast intake. I like to use plastic wrap. Use a good RTV around the coolant holes from the heads.

Hope that helps.

Stu :drinkers:
 
Where is the best place to get a new throttle cable and kickdown cable?

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I used the original 2bbl throttle cable. I bought a Lokar kickdown cable for the 904 trans from Summit and a new bracket from MagnumHP. I'll see if I can find a pic.
 
Got the 4 bbl on this weekend, seems to be running great, just waiting for the Lokar cables and bracket so I can take it for a drive.
 
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