The Stovebolt Site Forums The Shop Area Engine Shop 235 UPGRADE TO DUAL EXHAUST AND DUAL CARBS ?

I have a 1957 3100 series with a 235 6 cylinder, 4 speed transmission. I am thinking of installing a split manifold with dual exhaust and glasspack mufflers, also a dual 1 barrel carb set up. Looking to get better gas mileage a little better cruising speed on the highway and of course a real cool sound. Any input would be appreciated, pro's or con's, type of equipment good and not so good. Good idea - bad idea ? Enjoy your rides. Thanks_____Roller

Doubt you'll increase your gas mileage with dual carbs, but if you still want to do that, use an Offy dual single barrell intake manifold and a set of Fenton headers. Both are repopped if you can't find originals. You could use Rochester carbs, but Carters are better. Mufflers depend on how loud or mellow you want the noise. Cruising speed has a lot more to do with your gearing, not the engine.

I have a '50 3100 with a '60 235 engine and 5-speed trans with dual exhaust Fenton headers and a single 2-barrel carb. I believe I bought the whole set up from Stovebolt Engine Co. Except for a minor whistle that I haven't tracked down yet, I couldn't be happier with the set up. I can't give any feedback on gas mileage as I haven't installed a working gas gauge or speedo cable.

If you're ever a couple exits north on I-95, let me know and I'll let you take a look/listen.

I have tried several configurations of different brand intake/exhaust manifolds, and I will soon be doing what RedGreen suggests. Dual exhausts and single two-barrel carburetor (using original intake).

RedGreen, what carburetor are you using?

If you want both parts "duals", check out dual Fentons for both, from this vendor. The Fentons match up with each other; but, the Offy intake and and Fenton headers require some grinding on all parts.

The intake needs to be heated. I think that the simplest and safest technique is to use a single line, exhaust heat heat-plate.

Thanks RedGreen. I would like to do that. Let me know when that is convenient for you. I am retired And basically available anytime.

Nothing wrong w/ the Fenton headers & Offy dual intake w/o grinding them but if does improve the fit. Basically it is the flat surface where they meet the head that is typically uneven so it will depend on your parts. I did not have to surface grind mine but getting a good fit was an exercise. Stay away from the Rochesters as has been stated. They are notorious for leaks. The Carter/Weber duals that Langdon sells are good carbs but are a little too much under full power for a 235. They are progressives so at little throttle they operate as two one barrel carbs and were original to 84 or so Ford Escorts. Electric choke so you'll need to do some wiring unless you replace the harness which is generally a decent idea on these old babes. Do not recam if you want a decent idle unless it's with a 261 cam (6 cyl. Vette cam).
Long tailpipes/no mufflers will sound better than glasspacs IMO. That is what we used to do back in the day or a single exhaust with a steelpac muffler.

I ran this combo (offy+fenton) on my '50 1-Ton for 20,000 miles, several thousand with rochester B. and the rest with the carters.

I didn't notice any real seat of the pants power difference, when you consider that as you put your foot down, the throttle opens twice as fast. A 1-Ton that's always carrying a load is really a rocketship.

What I did notice though, was a SLIGHT improvement in fuel economy, about 2 mpg or so.

Where it really made a difference was at idle. I was able to get a much, smoother and slower idle. I really liked hearing that engine tick over.


It also looked really nice under the hood, and I liked that too!!!!!

I'm in agreement with using Carter YFs, IF you can find a matched pair. There's a Ford variant that's not only jetted much richer, but is entirely different internally. Personally, I prefer the Holley 1904. Easier to rebuild, easier to tune, and jets are the same as later Holley 2 and 4 bbl carbs.

I need to check but believe I have a Carter Weber carb on my setup. Looking at the Stovebolt Engine Co website, he recommends these for dual setup only but mine has been running great for several years.

I didn't have any problems matching the Fenton headers with the original intake manifold, and don't have any heating system on the intake manifold. Again with the electric choke, I haven't noticed any issues. But I also live where the intake manifold can heat up just from the ambient air temp. No need for heat in my truck.

Roller, I'll send you a PM and we can meet up whenever you'd like. I am not retired but will always take a break from work to take the truck for a drive.

RedGreen,

If you have on single carb from Langdon on your engine, it is most likely a progressive 2-barrel Holley-Weber, not the much lower volume progressive 2-barrel Carter-Weber (made for use on a 1600cc engine),

The 235 is about 3800cc and the 261 is about 4300cc.

Tm,
You're right. I do have the Holley-Weber 2-barrel carb. It took some thinking before I could remember that. I guess the typing fingers work faster than the brain cells lately. I didn't see the H/W carb on his website anymore so I'm not sure if he still sells it.

Tom is out of the progressive 2 bbl (Pinto) carbs, and can't get any more. One of them is a low dollar way to get better mileage.

The best way to improve mileage and cruising speed is to improve the differential gearing. Shoot for 2,000 rpm at cruising speed, which hits the torque curve best for acceleration and mileage.

I'm "running" Fenton's,dual exhaust,stacks from J.C. Whitney,(replacements for the "No-Power"(HAHA) "Derdge" "Lil Red Express". I opted to keep the stock intake/carburetor. Gas- mileage (in a 2-ton),increased impressively by about 3-4 M.P.G.!! I also have better accelleration,in ALL 4-gears,even with a load,with the rear on the "Hi-Side".The only other "mod's" that I'm thinking about adding,for performance,fuel saving,would be a H.E.I. distributor,and a single-wire alternator. And here in Iowa,I NEEDED to install a single-tube heat-riser,but that was included with the headers. Hope this helps. B.T.W...I LOVE the sound of the duals!! And as previously mentioned,the engine idles NICELY,at about 900 R.P.M's.

If you opt for different gearing,check-out Patrick's Antique Performance,in the "Stovebolt" link. They have All the stuff that helps make the 235's as reliable and dependable as they can get! Got any questions/ Call Patrick,or his son,Phillip,and they are happy to answer anything you can throw at them. When it comes time to up-grade to that H.E.I. distributor,they'll be hearing from me,again. Great bunch of people to deal with. just my personal opinion. Thanks.