Advice with '73 Valiant

Hello all,

I just purchased a '73 Plymouth Valiant in faded root-beer brown with
the 225 slant six from a co-worker for the grand sum of $0. While I'm a
car buff, I've never really worked on cars before, and I figure this is
a good basic car to learn how to tinker on and dream about fixing up
into a sleeper of some kind.

However, I have absolutely no skills and need to ask here for some
advice on a few issues:

- The car's major problem is that the 225 tends to stumble and quit
when accelerating away from a stop. This can be a bit awkward in busy
Seattle intersections.

The problem is worst when the engine is under the most load - the car
is at a stop and you are accelerating, especially on a hill and when
the engine is not 100% warm. In most circumstances if you really romp
on the throttle it'll carry through the stumble and then be fine; but
it's very difficult to do in those maximum load situations unless you
do a power dump - which is not ideal. In those cases, it helps to idle
away up to 5-10 mph and then you can hit the throttle and move on.

The engine is also very loud and you can smell exhaust in the cabin;
the previous owner thinks the problems are related and that perhaps a
leaky manifold or bad gasket could be causing both the stumbling and
the noise/smell.

The car had been sitting for some time; I'm also wondering if the carb
might be dirty.

Thoughts?

- Off in the misty future, I may do an engine swap. Not that I don't
like the classic slant six, but it's gutless and this one has already
been rebuilt. Any ideas on what would fit easily into a '73 Valiant? I
know ChryCo put 340s in that body of car; also 360s and 390s? It might
be cheap and easy to drop a truck 360 in to have a nice torquey
cruiser.

But that's a long ways off. I'd really like the car to be consistently
drivable first.

Cheers,
Chris Hafner

 

If you can smell exhaust in the car cabin the car is not safe to drive.

 

If it isnt a secondary ignition misfire I would bet that the accelerator
pump diaphram in the carb is shot and a thorough overhaul is needed.

That was a common problem back then on that slant 6. either the gaskets blew
out or the manifold would crack

Yup

Glenn Beasley
Chrysler Tech

 

A neighbor of mine has a 440 in a similar sized car...a Dart.

I recall clearly, long ago and never remember even fresh well maintained
slant 6 engines as anything but slow (in stock format). So don't be so
hard on the engine. It will last forever, but a torquey high HP motor it
is not.

 

Sounds like the accelerator pump is bad; also check the choke pull-off
and, hell, the whole choke mechanism for that matter.

Doubt it, although whatever exhaust issue you're having ought to be
addressed as well. While you're at it give it a full tuneup with new
plugs, wires, cap, rotor, points, condenser, etc. might as well change
the fuel and air filters as well. Make sure you set the valve
clearances also; the 225 uses solid lifters so part of every tuneup
ought to be a valve adjustment. Don't worry, it's easy. All you need
are some basic hand tools and a valve cover gasket.

Undoubtedly. I would either rebuild the carb myself, or if you're less
than handy, ISTR buying a reman Carter for a '69 Valiant for under $100
when the stock Holley started disintegrating inside. That was a few
years ago, but still, fairly cheap.

If it's been sitting a while you may also want to check the brakes; new
wheel cylinders, hoses, and master cylinder may be in order even if the
shoes are still good. Good news is the parts are dirt cheap. (MC for
the '69 was under $20) If you have front discs I actually have some
caliper seal kits you can have for shipping + beer money that I was
given basically because the guy that had them couldn't bear to throw out
perfectly good parts.

Finally, any car that's been sitting a while ought to have ALL the
fluids changed, that means oil, tranny, rear end, coolant, the works.
Repack the wheel bearings as well just on principle, and replace the
wheel seals. Don't be surprised if some rotational accessories crap out
on you soon, like the water pump and alternator. Don't get worried, all
that stuff is easy to replace and dirt cheap as well. (see a theme
here? I really love the old slant six...)

If you wanted to do that you could, but you'd have to swap the K-member
and probably would want to get brakes from a V-8 parts car. Also you
would want the tranny, driveshaft, and rear end from said V-8 parts car
as well.

Shouldn't be too difficult, those darn things run forever.

nate

 

This is not an easy undertaking, even for one with skills. Dropping a v8
into a Valiant originally equipped with a six will require replacement of
just about every mechanical part; k-member, suspension, brakes,
transmission, differential, etc. There are almost no common parts between a
v8 and slant six drivetrain and suspension. Even where you can bolt in the
engine without the other parts, the additional power will start breaking
parts, and the extra weight will cause handling and stopping problems.
You'll end up hurting yourself or, worse, innocent people who happened to be
near you when puny parts succumb to beefy engine..

To dream is fine, but change the dream to "drive this one until I can find a
good v8 project car".

Happy trails,

 

www.slantsix.org . Grab a (free) username and start asking questions.

Choke, choke pull-off, heat riser, OSAC valve, EGR control system,
carburetor. Ask (and search old threads) at slantsix.org .

It's fairly easy and inexpensive to wake up the slant-6; it doesn't *have*
to be gutless.

 

Most likely needs a new accellerator pump rubber - was a common
problem and some were even subject to a recall, IIRC

Most common problem that would cause this is a broken exhaust
manifold. Very common, particularly if they were torqued on too tight.

You would need a different crossmember - and the Venerable Slant Six
wasn't called the "leaning tower of power" for nothing. They respond
VERY well to tuning, and many performance parts are/were available.

I used to have a 170 incher that pulled 206 RWHP at 6500RPM on the
dyno through an automatic. Didn't idle worth squat, liked its gas, and
ate spark blugs for lunch, but it was a lot of fun while it lasted.

 

Here you're exaggerating somewhat. The K-member does have to change. The
"suspension" does not (though larger-diameter torsion bars improve the
handling regardless of engine). The brakes *should* be upgraded if they're
the base 9" drums; but they needn't be if they're the 10" drums or the
discs from the factory. The transmission must change simply because of a
different bellhousing pattern between 6- and 8-cylinder engines. The
differential used behind 6- and 8-cylinder engines in 1973 Valiants are
identical: A 7-1/4" unit as the standard-duty item; an 8-1/4" unit as the
heavy-duty option (and it was OPTIONAL regardless of how many cylinders
one had).

Here you're exaggerating a LOT.

Drivetrain:

-Same rear axle
-Same driveshaft

Suspension:

-Identical except larger-diameter torsion bars were factory-installed with
V8 engines

Here you're just makin' shit up. Lots and lots of V8-equipped Valiants,
Darts, Dusters, Demons and pre-1970 Barracudas were sold. Some of them
with very hairy V8s. They don't fall apart or have the "problems" you
mention.

Now you're doing a fine imitation of an ignorant kindergarten teacher.

 

The first half of this advice is sound and wise. The second half is
shitty. Every dollar spent on "remanufactured" parts would much more
effectively be set on fire. You're still out however many dollars, but you
don't have the hassle and frustration of trying to make this trash work.

There is a *WORLD* of difference between rebuilt/refurbished parts and the
"reman" junk you get from the parts stores. It's true of starters and
alternators. It's true of brake cylinders and whole engines. Probably
nowhere is it more true than of carburetors.

If he has disc brakes on his '73, they're not the same as the '65-'72
system you might've had on your '69.

Yep.

 

I didn't have a choice; the metering block on the Holley was
disintegrating, and I am prejudiced against Holleys to begin with so the
thought of being able to get a Carter on there was fairly appealing.
Actually it worked out fairly well; I bent a new section of hard line,
set the idle, and it was all good from there. I was a bit surprised
myself... now this was through a parts store chain that only exists in
the northern Virginia area so I can't say that you'd have as good luck
anywhere else.

They are for the later style calipers. Weren't for any of my cars, were
for a coworker's father's car.

nate

 

Wow, that sucks, about the rear end I mean. I had no idea that the
8-1/4" was optional. I'd probably want to upgrade anyway; I mean,
what's the point of going to a V-8 if you're going to go to a *mild* V-8?

Well... I would ASSume that the car probably has a 225/904. If I
wanted to stay with an auto, I'd want to upgrade to a 727 or later
overdrive trans, necessitating some driveshaft mods. Or, preferably, a
4-speed... wasn't there an A833 variant that had a fourth gear
overdrive? And finally, if the rear end gets swapped out, likely the
rear u-joint will be in a slightly different location (although I cannot
give you a 100% on this, most of my experience with six-to-eight swaps
is with Studebakers - there at least my statement is true, a Dana 27
requires different spring plates, U-bolts, and driveshaft than a Dana
44.) No big deal overall though, just bolt 'er up, measure, have custom
driveshaft made. 4x4 guys do this all the time.

In any case... for someone with "no skills" I would definitely second
the advice to just get the 225 running well before thinking about engine
swaps. But I have ALWAYS wanted to get an old A-body - maybe a '65-66
Dart or Barracuda? - and put a monster LA motor and manual transmission
in it, just because I think it would be cool.

nate

/misses the old A-bodies
//misses good junkyards even more

 

It could be ordered behind any engine, and it was part of several option
packages (e.g. taxi, towing, 340).

How come? LOTS of V8s came with 904s, even in trucks. A 727 is not
necessary until you're in _REALLY_ hairy V8 territory.

Does not fit under an A-body without extensive floorpan and crossmember
mods.

Yes, starting in '75.

 

So you did the right thing (replace the POS Holley with a better Carter).
No argument there. I'm picking on your advice regarding the *source* for
that Carter, is all.

 

Daniel J. Stern wrote:

Except he hasn't called you a "Chrysler shrill" yet.... ;-)

<grinning, ducking, running, hiding....>

 

If you switch to a v8, you have to switch transmissions ANYWAY, because
the /6 bellhousing is different. So I guess you might as well switch to
a 727. Personally, there's no smallblock out there that I wouldn't mind
having a properly prepped 904 (or the later 998 and 999 versions) behind
any smallblock short of a 360 stroked to >400 CID and running 10:1
compression. The 904 is basically just a very slightly scaled-down 727.
With the right number of clutch plates/disks in the clutches, and the
right choice of bands, its good for a LOT of power. I'd gladly run a
crate 5.7 Hemi in front of one.

 

Myeah, that cow was a 4th-grade teacher. She and her ilk are why there are
so many people running around so ignorant, yet so sure of themselves.

 

I guess I was just making the ASSumption that were one to swap a 225 for
a V-8 that it would be a pretty built engine of at least the 340 or 360
variety, and not completely stock either. Generally if someone is
building a grocery getter the 225 is more than sufficient Yes, I
know what they say about ASSuming...

nate

 

<snip>

Thanks to all for your repsonses! It's been both informative and
entertaining.

Sounds like the consensus is that:
- the stumbling and stalling problem is likely related to the
accelerator pump or perhaps a larger dirty/ready for rebuilt carb
issue.

With that in mind, I'll start looking around for a Holley 1920 rebuild
kit - although from checking around online they don't always have the
required accelerator pump parts. Failing that, I may try to find a
quality rebuilt Carter or Holley.

- The (likely) exhaust manifold problem is not rare and could require a
new(used) manifold and/or gaskets.

- It's possible but a lot of work to drop even a mild V-8 into the
Valiant. Back-burner all the way.

Many thanks to all of you. I wish I could say something to keep the
thread going, because I'm learning a great deal from every response.

Cheers,
Chris Hafner

 

Sinse you need both a carb and a manifold, look around for a complete
intake and exhaust from a "super six" with the 2bbl carb.