I recently got a '63 valiant conv.which has a 170cid engine. When speaking with a local rebiulder I was told I could not replace it wth a super six without suffering vibration. Something to do with whether the motor has a forged crank? Please respond if you can shed some light on this.Thanks

Do you mean you want to replace it with a 225 engine with a 2bbl carb, or simply put a 2bbl to your 170?
Either way, in all the research I've done I've never heard anything about super sixing an engine causing a vibration. The super six package is simply the 2 bbl carb and intake, with 2.25" exhaust and correct kickdown linkage - whether you have a forged or cast crankshaft shouldn't matter, as the cranks obviously aren't involved in this.
Can you elaborate any more on what he said?

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<i>D'Artagnan</i>
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Your mechanic is sort of right.

The "Super Six" was a factory high performance package offered on 1977-early 1980's cars and trucks. It consists of an intake manifold, a carb, an air cleaner, and a kickdown linkage. If you want to install these components on your 170 you will not have a problem or vibration.

Confusing things is the fact that in the 60s, Plymouth cars with the 225 cubic inch engine had a decal on the air cleaner which read "Super 225". Some people confuse the large 225 motor in the 60s Plymouths with the later "Super Six" performance package of the late 70s.

Starting in 1976, slant six crankshafts went from forged iron to cast iron. Some argue that the forged cranks are stronger, but all agree that the cast cranks are lighter.

In 1968, Mopar increased the size of the hub on the back of all slant six crankshafts. You cannot use a pre-68 motor with a pst-68 transmission, but you can use a post 68-motor with a pre-68 transmission if you purchase and sue the correct adapter ring. You can force a early motor/late transmission to fit together, but you will get vibration and eventual breakage.

You mechanic has bits of correct knowledge (different crank hub sizes, different crank casting methods, Super Six only coming on later motors), but has garbled them up.

When you say you want to install a "Super Six," do you mean simply a 1960s era 225 engine? Do you mean a two barrel carburetor? Do you mean a late 70s motor with a two barrel carb?

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Casually looking for a Clifford hyperpak intake for cheap.

What he said is that there are 6 different slant six motors and to put a forged crank engiine where a steel crank engine once lived whould create vibration. This did not ring true to me because balance is not contingent on what metal the crank is made of. I just wanted to run it by someone in case I was missing something. ps. I have a complete super six motor and thought I would freshen it up and it give the car some pep without turning into a pig at the pump

What I believe I have is a super six.It came with the 2bbl set up on it and was sold to me as a super six. I believe it to be from the 70s

You are right. It isn't the material the crank is made of that is the problem, it is the alignment between the crank hub and torque converter that can cuase problems. If the motor being replaced is a pre 68 motor, then you will have problems unless you deal with the torque convrter issue.

One this to be aware of, the "Super Six" package was just the carb and intake and exhaust, but in 1972 all slant six motors got an upgraded camshaft. So while the camshaft was not part of the Super Six package, it is an improved cam over the stock 170 cam you have now.

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Casually looking for a Clifford hyperpak intake for cheap.

Welcome on the board. This rebuilder you found is even more garbled-up in the head than Reed says. The only things you have to do when putting a '68-up slant six engine (any '68-up slant six engine, regardless of displacement, cast/forged crank, etc.) in front of a '67-down automatic transmission are:

1. Install a 1/8" annular adaptor ring between the smaller nose of the early torque converter and the larger counterbore of the later crankshaft. The adaptor ring is easily available and inexpensive.

2. Make sure to use the oil pan and oil pickup pipe that goes to the car you're swapping the engine into.

That's it. There are issues in hooking up a '63 Valiant's gas pedal to a 2-barrel carburetor, and that kind of thing, but "oooOOoooo, big scary vibration if you use a cast-crank engine in place of a forged-crank engine, oooOOOoo, can't do it!" is wrong.

Oh yeah, and there aren't six different slant-6s. There are at least seven, depending on how we count.

This doesn't necessarily mean you should swap the engine, it just means you easily can do so. The stock slant-6 camshaft was upgraded for 1965 and again for 1971 (not '72), and downgraded in '81 with the change to hydraulic lifters.

All bolt-on components (manifolds, distributors, etc.) can be used on all slant-6 engines, so you needn't change engines to install a 2-barrel setup.

If the engine in the car is sound, you may want to take a step back and rather than decide right at the start to swap the engine, focus on your overall goals for the car. Be as specific as possible, but don't focus on numbers (horsepower, etc.), focus on what you want the car to do that it doesn't presently do, and what you want it not to do that it presently does.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Oops. The posters car is a 63. He can use a 67 older engine as is, or the 68 newer engine with the annular adapter ring. There is no issue. The only time there is an issue, is when trying to use a 67 older engine with a 68 newer trans/converter.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

I always get that backwards. Sorry.

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Casually looking for a Clifford hyperpak intake for cheap.