Power differences, stock to dual carb and exhaust set-up

[Mr. Belvedere]

I am planning on giving old smokey as I call her an engine rebuild this winter. I am toying with the idea of going to the offy dual carb and split exhaust set up on my stock 217. But before I tack on an additional $1000.00 in bolt on performance to my rebuild, I'd like some idea how much power gain I will get for the trouble. I know alot of you out there have done it, was there enough bang for the buck to make it worth while. Also, where is the best place price wise to get such a set-up?

[greg g]

The biggest bang for the buck seems to be to raise compression. Considering tha the stock was a bit over 6.5 to 1, and most cars today running regular are running 9 to 1 there is a lot of room for more squeeze. Milling the head and decking the block are relatively inexpensive machining processes and yield good results. These cars are geard so low that it doesn't make much difference in 1st and second gears. Where I feel it is between 40 to 70, in high gear where, the pedal to the metal seems to be the most different, which is of the most use in normal driving anyway. You might want to contact Charlie Ackers (Olddaddy of this forum) as he just posted a note about having a set of manifolds he had mad up for a customer who stiled him. I don't know if he was including carbs and linkage, but it may be worth your while to contact him. George Asche who contat info is in the suppliers section also does manifolds and carbs. The jury is out on whether after market of modified stock manifolds flow better, but any breathing improvment you can make on your flat head will be beneficial. You might want to consider a regrond cam shaft also to make the job complete.

Besides even if it doesn't work to provide more performance its still fun to look at....

[Justin Slingsby]

I milled my head and polished the intake, exhaust and combustion chambers. I am running a Fenton intake with dual B&B's I also am running a split exhaust manifold from George Asche and straight pipes. I noticed a significant change in how the motor performs. It pulls harder through gears. As mentioned previously it is all about getting these motors to breath better. It will never be blinding neck snapping power but that is not the reason we use these flat motors.

[Mr. Belvedere]

Nope I don't expect that it would perform like a hopped up small block v8. These engines have to long a stroke to ever be fast, they are more about torque than anything. I just want to know if those of you have done it feel that its that much better than stock that it is worth the up-grade. Also, is it difficult to sync the dual carbs?

[Mr. Belvedere]

I also wonder about fuel economy differences?

[Plymouthy Adams]

is it difficult to sync the dual carbs?

Not with good secure linkage and the correct syncro tool...

[hkestes41]

Mr. Belvedere,

Langdon's Stovebolt seems to have fair pricing compared to what I was able to find elsewhere. I purchased all the parts shown for just over $1,200. Included the Offy intake, Heat Plate for intake, Carb Adaptors, New Carter/Weber Carbs, Linkage, Mopar Mini HEI, Coil, Finned Side Covers, Ceramic Coated Cast Iron Headers, and Air Cleaners.

As for the performance increase, I don't know as I have not installed them yet. Should open up the breathing quite a bit and as was said earlier will be good to look at.

[Mr. Belvedere]

Seems pretty reasonable alright, was that a kit or just a bunch of items you purchased individually? Is the electrical stuff 12v? Thanks

[Powerhouse]

Nice setup "hkestes41"...I'm also in the market for this stuff...would you be able to make alist of suppliers of these items....I know that must have taken you a while...I'm sure plenty of us in the market would really appreciate it...I'm not to good with researching parts. Thanks a million if ya can and thanks a million if ya can't...

[38plymouth]

I just put on a fenton aluminum head and a George Asche split exhaust manifold. I drove it to shop a few minutes ago to have the exhaust pipes bent up. It definately has more power with just those two changes and I think it will run even better when the exhaust is on and I get the carb adjusted a little more. I went up a hill in third gear that normally gave me trouble and I was able to accelerate up it today. I might go with dual carbs this winter if I can find something I like.

[greg g]

my fuel usage went from 16 to just around 19 highway driving. I am running a 230 out of a 56 plym. I need to do a bit of timing and carb adjustment, to get it running in tip top shape. I get a little bog starting out and some part throttle burble on steady low speed cruise or deceleration. Other wise I'm liking the changes. My intake if a Fenton, George A did the carbs. Exhaust is single with 2 in ID pipe and a Dynomax turbo flow muffler.

[Powerhouse]

Oh...sorry...I missed the part about Langdon's Stovebolt being a good place to buy from...I guess was too busy staring at the foto and dreaming of it on my p7

[Suddensix]

I agree with Greg my 218 has had the head shaved and is now about 8 to 1 c/r. I have a fenton intake, dual B&B's, headers and dual exhaust. First and second gear are a little livelier but from 40 to about 65 mph there is a huge difference. I didn't notice any major difference in fuel mileage, I get about 21 mpg at 60 mph in overdrive. You can sinc the carbs with a length of heater hose and a good ear if you don't have the proper tool. I plan to pull the engine this winter for a freshen up and will install a performance cam at the same time.

[Justin Slingsby]

I have been thinking of a beefier cam as well when I build my Industrial motor. Is Edgy the only cam maker for these motors or is there other options?

[Guest rockabillybassman]

If you only do one thing, mill the head .060 - .070. This is the most beneficial thing because it's the ONLY thing that benefits the engine across the whole rev range. Twin carbs, better exhaust and cam only come into their own once the revs get up, ie: 40mph+ in top gear. In fact, twin carbs can in some instances detract from low rev performance, something to do with flowing too much air. But they sure do look good!

[Mr. Belvedere]

Yeah I did wonder about it being too much carb especially with out any cam modification. I wonder what a two barrel carb might due on a stock intake with an adapter in between, if they even make an adapter like that? I wonder if the adapter pictured above for the offy intake would bolt up to a stock intake? Hmmm... I will definitely mill the head for increased compression.

[greg g]

Langdon's has those adapters. The Chrysler 2bbl option available in 56 yielded about 8 HP. The adapters are available at various speed parts houses. I fhave seen the for 15 buck up to 40 so shop around if you decide to go that route. Carburetor used was a carter BBR, usualy from a 273 or 318. probably makes the linkage issue real simple and and synching is a non issue.

[Mr. Belvedere]

I was thinking about one of those new carter/weber two barrels picked above. I wasn't aware that chrysler offered a two barrel 6cyl in 56. What size six was it?

[greg g]

a couple folks have located some of the manifolds. I think it was a one deal only or perhaps through 57. Wonder if it was a police or fleet car I got a carb kit to rebuild the BBS carb that was on the 56 engine, and it contained some extra parts obvioulsy for the 2bbl. Here is a shot of the carb to intake manifold. The carter weber is likely a good choice if you want to go this way,the reference to the original type carb was more for CFM comparison.

[Guest jjmorrse]

Is the fenton head necessary, or can one just shave the stocker?

[greg g]

mill the stock head. There is a chart on the forum that shows how much off equals what CR. I did 40 off the head and 10 of the block, the 56 started at 7.6 to 1 so I figure I enede up with at least 8 or 8.5 to 1. The oversize pistons factor marginally into the CR calculation also.

[Mr. Belvedere]

How would I search or where do I look for said chart?? Thanks

[greg g]

like this

[hkestes41]

Seems pretty reasonable alright, was that a kit or just a bunch of items you purchased individually? Is the electrical stuff 12v? Thanks

Not a kit just individual parts. Not all Mopar parts sold by Landon is on their web site so I would suggest ordering a print catalog or calling. Tom Langdon was very helpful and forthcoming with information and advice.

Yes the distributor/coil are 12 volt.

[jimwheeldon]

Do you think removing .100 would be too much on a 1950-218?