My slant still has the stock 1 bbl and i was wondering what was the cheapest way to get the most hp out of it and if anyone knew approximatley how much power gain I could expect.

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1975 plymouth scamp

This is in your '75 Scamp?

OK...which transmission do you have? Is this a Federal, California or Canada-emissions car? With catalytic converter, or without? Where do you live? What kind of emission tests or inspections do you have to pass? How many miles do you have on the engine? Any modifications under the hood or under the car at all? What kind of improvement are you looking for -- what does the car do that you don't want it to do, or not-do that you want it to do? What means "cheap" to you, what's your budget? Would you spend...$50? $500? $5000?

Horsepower numbers aren't much use. "Fast enough and quick enough, does what I need, does what I want the way I want it to do it" is what matters.

You added all that stuff to yours?

right now everything under the hood is stock i havent added anything. It has the three speed auto trans and i believe it is a california emissions with converter. I live in northern KY and our emisions testing has been dropped. currently there is around 57000 miles on the engine. right now im looking for an increase in acceleration, the current pickup does not work out well at all it is way to slow, I would also like it to be a daily driver so it would have to start relatively easy. I would like to see around the performance of a small block v8 if possible. MY budget so far is around $500 to start but will most likely raise to get exactly what i want.

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1975 plymouth scamp

and yes it is in my 75 scamp

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1975 plymouth scamp

Will the Holley 5200 or Weber 32/36 carb. work with the Dual intake Manifold ? if not what will be the best carb to use? http://www.offyparts.com/product_info.p ... 862c614fab

OK, with this information it gets a lot easier to comment. As others have said, a complete tune-up is almost at the top of the list (it's number 2. Number one is buying a '75 Dodge/Dart or '75 Plymouth/Valiant Factory Service Manual -- the one printed by Chrysler Corp, not an aftermarket book from Haynes, Chilton, etc. Find one on eBay or from www.autolit.com .)

Make sure the engine is in proper tune and everything's in good order. There's lots to check. Carburetor condition and adjustments, air and fuel filters, PCV valve and crankcase breather, tappet clearance, ignition timing, vacuum and centrifugal spark advance mechanisms, thermostatic air cleaner function, EGR function, maniifold heat control valve function, choke function.

Next, here's a simple, zero-dollar mod that will get you better driveability and acceleration: Bypass the OSAC valve. It is located on the side of the air cleaner housing (not the snorkel where the air comes in, but the actual round housing itself), and has two small vacuum hoses on it. There is one hose running to it from the carburetor, and another hose to the valve from the distributor. To bypass the valve, run a properly-sized vacuum hose from the carburetor directly to the distributor, using the same port on the carb and distributor that the original hoses (to the OSAC valve) hooked to.

Breathing (in and out) is key. Your '75 California-emissions car has a very small carburetor and a very restrictive exhaust system. Federally, it's illegal to delete the catalytic converter. Many people do so anyhow. These early catalyst systems with uncontrolled carburetors are of rather little value, but a properly-chosen catalytic converter in good shape offers next to zero restriction, so you choose. Much has been written about mufflers; I don't like the "turbo" types -- too noisy (drone on the highway at cruising speed). When the factory wanted to put a low-restriction exhaust on the A-body in '76, they simply used a V8-sized system (2-1/4" headpipe all the way into the muffler, 1-7/8" tailpipe). Big enough for a 318, certainly big enough for a 225.

The "Super Six" 2bbl setup found on '76-'80 Aspens, Volares, and so forth with Carter BBD carburetor is a good, inexpensive and easy swap. Get everything: Intake manifold, carburetor, choke thermostat, air cleaner, throttle cable (shorter than the one you have now), trans kickdown linkage (INCLUDING the little kickdown lever on the transmission -- shorter than the one you have now), all the linkage brackets that attach to the manifolds. You don't need a different exhaust manifold; they're the same.
The Offy twin 1bbl setup is nifty as heck, to be sure, but it more readily lends itself to installation on the earlier ('60s) cars than on a '75.

Another area to give serious thought to is your car's gearing. Right now it almost certainly has a 2.76:1 rear axle, and the '75s had tall tires -- I'm betting you have something like P195/75R14s on it -- which is a fine combination for cruising along on the highway but tends to give "zero to sixty in 25 minutes" type acceleration. 3.23:1 in combination with those tall tires works a lot better as long as you don't do a lot of constant 75mph highway flying (higher engine revs with 3.23s get annoying, but not unbearably so.) City MPG in stop-and-go driving will go up with 3.23s compared to 2.76s; highway MPG will go down with 3.23 compared to 2.76, so again, you get to choose.

www.car-part.com for finding used parts.

After the tune up and bypassing the osac valve, I think the biggest single upgrade I ever made to a slant six car with an automatic transmission was changing the rear axle ratio.

I once put a set of 3.91 gears in an otherwise stock 72 dodge dart. The change was unbelievable, and allowed me to smoke one tire all night long if I wanted. I was young and dumb, and eventually killed the motor by running the engine rpms into the danger range one too many times. Not a good mod if you plan on doing any highway trips, but great for a satuday night joy ride. Should be able to get a nice 8 1/4 axle with shorter gears installed for about $250 if you shop around.

Then, super six.

Just my experience, and depends on your needs and future plans.

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1980 Aspen 225 super six

for an intake I was thinking on trying to fabricate my own 3 carb setup. My family owns a metal working shop so i would have everything needed. what would your views on this idea be?

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1975 plymouth scamp

My thoughts:

Home fabricated 3-carb setup + daily driver = 0.

Constant tweaking and "tuning", bitchy starting, idling and low-RPM running, poor fuel mileage...

what will be the best carb's to use with the Dual intake Manifold Dan? or any one.

jay -

I have to Offy 2x1. I think the carb issue depends on what type of linkage you currently have.

My 63 Dart has a "rod" linkage (not cable). The Offy comes with a lnkage kit that makes it pretty simple to just add another of the same "rod" type carburator. (Carter or Holley).

The Offy 2x1 manifold actually was first produced in the VERY early 60's (I'm guessing 60 or 61). I'm speculating that the ones being sold are NOS or NORS, since the instructions refer to Dodge Lancer or something like that (i.e., pre Dart).

The instructions also don't have a zip code. They were printed before zip codes (or copied from instructions that were printed before zip codes).

If you currently have a cable linkage, I could see yourself driving yourself crazy trying to come up with a workable linkage for two carbs.

That being said, sometimes I see Offy 2x1 kits on Ebay that have been converted to Weber - and I'm guessing those would work with a cable linkage.

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1963 Dodge Dart, motor by Doug Dutra, Offenhauser two carb intake, Pertronix, Clifford 6x2, Flowmaster 40's, Erson RV15/295 RDP, head work. Addco anti-sway bar, urethane suspension bushings, KYB's, racing leafs, SSBC discs. Need ZDDP? Get STP.

'61.

No, the ones being sold are new-new stock, as in "arrived at Offenhauser's warehouse from the foundry two weeks ago". (NORS doesn't apply, BTW, it means "New Old Replacement Stock" and is applied to original-type parts first packaged by other than the automaker or OEM. For example, a never-installed new set of Raybestos brake shoes from 1962 would be NORS, while a never-installed new set of Mopar brake shoes from 1962 would be NOS. Since only Offenhauser ever sold a twin downdraught 1bbl intake in North America, there's no "R" involved.)

That's true. The manifold, linkage kit and instructions have never been updated. Neither has the Offy aluminum rocker cover, which lacks provisions for anything but an oil cap (no breather, no PCV, etc.) Offenhauser is a small family-owned company. They do not have a website. If you succeed in finding their phone number, Mr. Offenhauser answers the phone. He was very interested to hear how the rocker cover might be updated to be more useful, so I'm working on putting together some 'show and tell' for him on that. If that is successful, maybe we'll look at a cable-type linkage kit for the twin 1bbl.
YEP!

DS

I have the 1967 dodge dart. will twin 2bbl cab work? i was going to order this product. has soon as i fine out what will be the best carb for this set up. sice pro line is off line for now.
http://www.offyparts.com/product_info.p ... 862c614fab

I would suggest going to http://www.stoveboltengineco.com/ and buying a pair of his rebuilt 5200's. There is plenty of room on the carb mounting pad to mount these carbs. This is basically what Proline/Redline does with their dual carb offerings on the Offy manifold.