Carburetor upgrade and intake manifold

[Johnjgonzo8D]

I was planning on upgrading my 1 barrel holley carb to a 2 barrel. Does it matter exactly which carb I use? I was just going to buy a 2 barrel holley, but I don't know which to buy. Also I wanted to upgrade my intake manifold because obviously a 1 barrel type won't fit the 2 barrel carb. Are there any further steps I should take in this upgrade?

 

[1970Dart198]

If there are any junkyards/pull it yourself yards around, try and find the super six exhaust manifold, its larger in diameter and allows your engine to "breathe" better. Also, will you plan to run manual or automatic choke? If you plan to run the automatic coil-type choke, a set of Doug Dutra's Dual exhaust manifold setup is the BEST manifold setup for any slant six. You can get the automatic choke setup, as well as the heat riser for easier cold starts, and better mileage.

I would definitely recommend the super six air cleaner housing as well, it'll make the engine look good versus throwing the Chinese-made chrome "cold air intake".

Is your dart automatic or manual transmission? If its automatic, buy the Lokar kickdown cable and fashion a mounting bracket for your automatic transmission.

I would highly recommend the HEI ignition upgrade if you didn't already. Points ignition, especially the new "re-manufactured" distributors, are unreliable. I did a Pertronix points-to-electronic conversion and simplified the ignition.

There are tons of articles on super six setups and conversions. Just do some research!

Happy Hunting!

70Dart198

 

[Johnny Dart]

Do yourself a favor, and go straight to a 4 bbl. You will end up doing it anyway.

Offenhauser or Clifford intake. Clifford headers. Ede 500 or Holley 390 and your good.

 

[krazykuda]

If you go 2 bbl, you have to choose between the smaller stock 273/318 two barrel or the larger Holley 2300 series 2 bbl. We have a 2300 on our slant 6. Getting the kickdown linkages and throttle cable brackets "matched up" is a bit of a challenge....

 

[nm9stheham]

You are probably best off just going to the Super Six conversion with the rest of the engine being stock. With no other mods to the /6, the engine's restricted breathing makes any large carb a dissappointing effort. You will actually get more improvement with a mild cam change (even keeping 1 BBL) to overcome the small valves; even just going to the 71 or later cam will help breathing. Then exhaust enlargement.

You ought to spend some time reading the articles here and asking questions: www.slantsix.org

 

[Johnjgonzo8D]

Thanks guys, I will definitely be reading alot about it.

 

[pishta]

I dont know if the super six exhaust is special...maybe in the choke well only? NEver heard they flowed any different. Limit yourself to the BBD or the Holley replacement carb, not the big holley 2300, the bores dont line up without a adapter. Manual cars are easy to convert to 2bbl. Autos need the unique 2bbl kickdown linkage thats worth more than the intake. look for a super-six package here, carb,kickdown and intake. SS Exhaust is wasted weight on shipping.

 

[Serj22]

Do yourself a favor, and go straight to a 4 bbl. You will end up doing it anyway.

Offenhauser or Clifford intake. Clifford headers. Ede 500 or Holley 390 and your good.

IF you're going to put it that way... do yourself a favor and go straight to a turbo, you'll be doing it anyway. lol.

I set a Weber 38/38 on top of a supersix manifold. It worked great till I went turbo.

 

[barbee6043]

I say, bypass all this and get the old reliable 426 hemi with the crossram and big honking honkers!! LOL

 

[Johnny Dart]

IF you're going to put it that way... do yourself a favor and go straight to a turbo, you'll be doing it anyway. lol.

I set a Weber 38/38 on top of a supersix manifold. It worked great till I went turbo.

Just speaking from my personel experience. Turbo or V8 would be the next step.

If you must go 2bbl, go with a Carter bbd from an early/pre smog 318.

 

[Johnjgonzo8D]

Yeah the reason I am going with the 2bbl and intake is because I am still in high school and I work mnm wage, so upgrades are limited to cheap spending. So the 426 HEMI will be a bit out of my spending range hahaha.

 

[Johnny Dart]

High School and working...Props to you.

Since money is tight, another alternative would be to stick with the 1bbl.
Add a free flowing 2.25" exhaust and add electronic ignition.
Had this set up early on, and it ran nice.

Welcome to the site.

 

[ESP47]

If there are any junkyards/pull it yourself yards around, try and find the super six exhaust manifold, its larger in diameter and allows your engine to "breathe" better. Also, will you plan to run manual or automatic choke? If you plan to run the automatic coil-type choke, a set of Doug Dutra's Dual exhaust manifold setup is the BEST manifold setup for any slant six. You can get the automatic choke setup, as well as the heat riser for easier cold starts, and better mileage.

I would definitely recommend the super six air cleaner housing as well, it'll make the engine look good versus throwing the Chinese-made chrome "cold air intake".

Is your dart automatic or manual transmission? If its automatic, buy the Lokar kickdown cable and fashion a mounting bracket for your automatic transmission.

I would highly recommend the HEI ignition upgrade if you didn't already. Points ignition, especially the new "re-manufactured" distributors, are unreliable. I did a Pertronix points-to-electronic conversion and simplified the ignition.

There are tons of articles on super six setups and conversions. Just do some research!

Happy Hunting!

70Dart198

Good info here except there is no "super six exhaust manifold". All slant six exhaust manifolds flow the same. The only differences are open choke pockets and closed choke pockets.

John, whatever you do, don't go to a parts store and buy a remanufactured carburetor. Your stock options for the super six are the Carter BBD and the Holley 2280. I have the BBD on my car and it's worked fine for years but I made sure I bought a NOS carb. Spent far too many Saturday's working on "remanufactured" carbs only to realize that nothing I did had any effect on them because they just come broken right out of the box.

Also remember there are two types of Carter BBD's on mopars. The slant six type and the small block v8 type. They are nearly identical other than the choke linkage. You'd have to rig up your own choke linkage if you got the v8 version of the carb. Which there are more of. If you get the slant 6 version your choke linkage will mate right up to it no problem.

 

[krazykuda]

Yeah the reason I am going with the 2bbl and intake is because I am still in high school and I work mnm wage, so upgrades are limited to cheap spending. So the 426 HEMI will be a bit out of my spending range hahaha.

Good for you being in high school and getting into the old cars!


If you are tight for money, you may want to consider just saving up for a v-8 swap. They are cheaper to modify and build than slant 6's, and parts are much easier to find.

A 273 or 318 would swap into your car better than a 340 or 360.

273's and 318's go real cheap, and sometimes you can find people giving them away.

The early 273's from 64 - 67 (possibly 68 but not sure) had forged cranks. You can bolt a 273 crank into a 318 instead of the stock cast iron crank (keep the 273 vibration damper with the forged crank). You can make a nice running v-8 with less money than you can get with the slant 6. Just build yourself a nice running 4 bbl v-8 daily driver car and have some fun with it. :glasses7:

 

[ESP47]

All he wants to do is add another barrel to his carburetor. If he was doing a V8 swap he'd need to swap out the entire drive train, plus k frame/conversion mounts, most likely bigger brakes, and different wheels unless he can keep everything small bolt pattern.

 

[Darter6]

And after all that,,, you will find not much of a improvement over the 1 barrel...Going to a two barrel.

 

[vynn3]

And after all that,,, you will find not much of a improvement over the 1 barrel...Going to a two barrel.

Gonna have to disagree on that.

I went from a stock 1bbl to Super Six and Dutra Duals, and it really woke the car up. It certainly wasn't a race car, but for daily driving, it was a very nice improvement.

People have been telling me for years not to bother modifying my slant, I'll eventually swap in a V-8. Or don't bother with a 2bbl, you'll only end up with a 4bbl. Well, I'm very happy with my rebuilt, mildly modified slant and 2bbl. The only further improvement I want is a T-5, which is my winter/spring project.

OP, don't waste your money if you want a LOT more power. But if you think incremental improvements will help you enjoy the car, than go for it, and ignore the power-hungry naysayers who never seem to get enough bang for their buck.

 

[Johnjgonzo8D]

I like the idea of a swap to the v8, but then again I would have to change a whole lot of components. I think the 2bbl idea is right for my situation, and I'm not going for insta-racecar right away. I am going for the incremental upgrades, Thanks to everybody helping me with advice. I will give some serious though and planning into this. All the praise and welcome is appreciated, this website is super awesome!

 

[Johnjgonzo8D]

I like this idea

 

[ESP47]

My car went from being a turd with a 1bbl to at least being able to keep up with traffic without flooring it all the time with the 2bbl. Still isn't quick by any means. Bet the Dutra Duals really open things up. I was going for gas mileage though and am happy with my current 20mpg.

I'll tell ya the best "bang for your buck" if you want to go faster off the line would be rear end gears. My slant has 2.76 gears and it takes until about 40mph before it wakes up and starts to go. Drove an old worn out 1bbl slant 6 with 3.23 gears and that thing had the tires chirping easily. Felt like I had 50 more horses instantly.

 

[krazykuda]

My car went from being a turd with a 1bbl to at least being able to keep up with traffic without flooring it all the time with the 2bbl. Still isn't quick by any means. Bet the Dutra Duals really open things up. I was going for gas mileage though and am happy with my current 20mpg.

I'll tell ya the best "bang for your buck" if you want to go faster off the line would be rear end gears. My slant has 2.76 gears and it takes until about 40mph before it wakes up and starts to go. Drove an old worn out 1bbl slant 6 with 3.23 gears and that thing had the tires chirping easily. Felt like I had 50 more horses instantly.

But then you will loose some of that economy when you change gears...

 

[barbee6043]

I've had a couple dusters, dart sport with the super six, to me quite a bit more ump, more fun to drive. for sure more responsive with better gearing but will affect mileage which the hard working boy probably doesn't need.
cudos for working. it will t each you more than you know right now. good luck..

 

[nm9stheham]

^^^ Even 3.31 gears seems like it is really winding out on the interstate with no OD gear.

From have driven one for some time 'back when', the 2 BBL Super Six will really make a difference, but keep in mind it had the later cam that could make use of the extra breathing. So if the OP has the original engine in the car pictured, it won't make quite the same difference. A cam change in a /6 is not too bad; the hard parts are getting the oil pump off (they stick pretty good), the lifters up (they get a varnish ring in the bores), and then carefully moving the cam in and out (use a looong bolt inserted into the cam bolt hole for leverage). (Removing the pan helps a lot but you can get by if you really have to.) A new timing chain change will get rid of any timing retard on the cam that has a pretty noticeable negative effect on the engine.

I'll be putting a special cam ginned up by (someone-who-is-highly-recognized-for-what-they-are-doing-but-who-I-won't-name-since-I-don't-have-his-permission) to use with the 1 BBL and otherwise stock system that emphasizes torque up 4500-4800 rpm....plenty for the road. A simple head shave will easily bump up compression; the /6 head can be shaved a lot, and you don't have to worry about matching machine work on the intake manifold like on a V engine. Moderate head shaves don't require any valve train mods on the push rods or anything (at least with the solid lifter cams).

 

[Darter6]

Please let us know how things work out.

 

[Johnjgonzo8D]

I will definitely keep all you posted. Thanks a million