I have 225 slant six currently with a single Carb set-up. I bought a complete 2 barrel conversion recently and have a few questions.

1. Is it worth doing the conversion. Will I notice a power difference and will it dramatically affect gas milage?

2. Can I use my existing linkage and throttle cable?


Any input would be appreciated.

Should feel the difference. I believe you can use the existing parts. one thing you may want to keep in mind that the true restriction in a slant six is the exhaust. Think seriously of getting a set of headers or dutra duals. Getting the exhaust out is as important as getting the fuel in.

Actually youll need to use a different throttle cable if the setup didnt come with one. A cable from a v8 car will work.

Youll need the two barrel kickdown linkage or go with a lokar cable or a bouchillon cable.

Lastly the head is the worst offender to flow, not the exhaust. Go 2-1/4" on the exhaust and call it a day.

I did a 2bbl swap several month ago and I wish I did it years ago. The dart runs like its gota stock 318 now and Iim still running the stock 1-7/8" exhaust.

Btw, expect mileage to stay the same or improve.

I shaved the block and head to raised the compression and went .30 over bore so she should really move out with the 2 barrel bolted on. I already have 2.25 exhaust but was debating on putting a more aggressive muffler but I have read horror storied about "drown" when your at cruising speeds.
Any thought on a muffler??

Matt, did you have to swap the distributor???

Matt, did you have to swap the distributor???

What vehicle is your slant in Darren?

Have you read the Super Six article yet? It is here: http://www.slantsix.org/articles/supersix/article.htm

Short answers:

(1) Possibly. Many variables here. Most people have nothing but good to say about the conversion, but you need to be sure to get a good condition carburetor.

(2) Depends on the vehicle being worked on.

It depends on what muffler you already have. For years many generic replacement units were restrictive by design in order to keep the sound levels down. A 2-1/4" unit would neck down to 1-3/4" or less inside the inlet pipe. Walker's Super Turbo line seems to offer a good balance of flow, sound, & cost. The resonance/drone problems seem to occur more often with "hi-perf" straight-thru muffler designs, & only at specific rpm-load points. I had that happen & was able to "tune" it down some by adding a glasspack to the tailpipe.

Ideally, you'd tap a small hole in the head pipe & connect it to a low pressure gauge (such as a vac-fuel press gauge), then go for a drive. If you have under 2 psi backpressure upstream of the muffler under all conditions (incl WOT) then you don't need to change anything.

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63 Valiant Wagon
225 - 4 bbl