Thread: 1968 Plymouth Valiant 1st Gen HEMI

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Ouch - gotta take care of the back, Mike! Some of my "well intended work days...." end abruptly with a sharp pain in the back which tends to shut me down. Advil helps but getting old is a real pain sometimes!

Glad you're wrenching and building - always enjoy your posts and the creativity you bring to the sport!

Regards,
Glenn

I thought of your project yesterday when I spotted a Valiant like yours merging on to the interstate. It was orange and had some real loud pipes exiting just ahead of the rear tires. I gave him a thumbs up and he jumped into the throttle to show off a bit. Ain't no telling what was under the hood, but the engine wound up pretty quick like he had alot of gear in the rear end.
Oh, I loved your mama's saying about getting old.
Nolan

Yeah Glenn the last couple of days pretty much sucked. The 2 trips to Tucson aggravated the back quite a bit so yesterday was pretty much just resting……which really bothers me when I feel I have something to do. It also gets a bit expensive as I can still cruise the net for parts to buy.

Hopefully today will be better and I’ll get a couple hours in.


It is hard to tell what he was running Nolan. Hell there are kits out there to bolt everything from the original slant 6 to 440s to 426 based HEMIs to the newer Gen 3 HEMIs in them. Of course there’s nothing to do a Gen 1 HEMI like I’m doing but that’s what makes it challenging.

Yeah gears are really what can turn it into a fun ride. With the overdrive transmission it lets you have the best of both worlds. The easy route for me to take on this project would be to use a regular 727 transmission (which would bolt in) with about a 3.20 gear. With the 46RH overdrive transmission I can run a 4.30 to 4.56 gears and have an effective ratio of 2.96 or 3.14 respectively. It will take a fair amount of tunnel mods, but It will be worth it.


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I played with Mopars when I was young, a '70 340 Challenger. This was around '74-75. I remember in '68-69 my brother was doing alot of street racing in our Daddy's SS396 Chevelle. He got whipped by a Dodge Dart Swinger with a 340/4 speed. They weighed about 2700lbs, which is the same as your Valiant. They were also built with 426 Hemi's so it seems a hemi could potentially be a bolt in. This is assuming the Valiant is the same chassis as the Dodge Dart?
Interesting project.

You’re right the Plymouth Valiant is the same basic chassis as the Dodge Dart of similar years. Dodge did build (in conjunction with Hurst) 80 426 Hemi Powered Darts to run in the Super Stock class (with warranty/registration disclaimer). Conversion of Darts and Valiants to 426 power was/is a fairly common swap.

The Gen 1 Hemi Chrysler HEMI (331/354/392) however is pretty much a completely different animal than the 426. The Gen1s are actually closer to the MOPAR A engines (318s) than the RB based 426s. Actually, with what’s available for the 426 swaps, the Gen 2 HEMI would be pretty much a bolt-in in place of the 440 that’s currently in the green Valiant.

Having the transmission tunnel and differential pinion offset to the passenger side and the location of the steering gear on the drivers side makes it interesting getting everything lined up. The 354 swap into the Valiant is a little trickier but so far there really aren’t show stoppers. I suspect it will be like putting the 500 Caddy engine in the El Camino. It looks like there is one sweet spot and a ½” in any direction causes issues.

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Oh, ok, I'm now edjumacated on Gen 1/2 hemi's. I didn't know the 426 was different. Just bench racing with ya. Carry on.
Nolan

Originally Posted by Mike P

....the RB based 426's.

Mike,
My Mopar history is limited. What is the "RB base" for the 426 Gen 2 hemi's?

Roger when Chrysler transitioned away from the First Generation HEMIs and started Corporate engine sharing they designated the small block Poly engines (318s) as the A engine. In 1958 They introduced the first of the Big Blocks which they designated the B engine. The following year they introduced the tall deck versions of the B motors with a longer stroke crankshaft and they designated these the RB, standing for (take your choice) Raised B motor or Raised Block.

All factory B motors use a crankshaft with a 3.375” stroke and RB motors use a crank with a 3.75” stroke.

Basically the 426 HEMI evolved from 426 Wedge engines (although the blocks are not directly interchangeable) their external dimensions, engine mount lugs and bellhousing bolt pattern are the same.






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Mike, when we did the Hemi swap into the '65 Coronet we copied the "factory" mod to give a tiny bit more clearance when shifting the engine to the pass side. That was to cut off the top of the shock tower, flip it over, weld it back in which lowered it's profile just a bit that gave more clearance. Is that done with the A bodies too?

I was unaware of the mod so looked it up, good information but I'm not sure if it applies to the A bodies.

I've found 3 vids of A body/1st Gen hemi swaps. They're each just a bit different and unfortunately none really give a lot of detail (so far I haven't found ANY build threads from someone who has done this swap. As far as I can tell there were no shock tower mods.


https://www.youtube.com/watch?v=qFK_c15K2fE

https://www.youtube.com/watch?v=LbYiVVmPBA4

https://www.youtube.com/watch?v=IpH1XiYsjlI


I've pretty much poured over all 3 and got some ideas but but like I said I not a lot of good detail in them.

On a side note the guy I bought the Green 68 from dropped by yesterday and dropped off the Holley Predator. Unfortunately it was just the throttle body so there will be a bunch of parts I'd have to buy separately if I go that way. I've done some research on the differences between the Predator and Sniper, and it actually looks like the Sniper will be a better option for this project.


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That blue Dart was sweet, thanks for sharing the videos.
I remember the 413 and 426 wedge engines. I worked on the weekends at an auto parts store for extra cash(hotrod money) when I was a apprentice electrician. A regular customer had a ~'63 Belvedere with a 413 with the cross ram intake with two fours. I seem to remember he also had a 426 wedge stashed in his shop. It was a dedicated race car with the push button automatic. He was a damned good mechanic and had lost his left arm up to the elbow in an accident.
He was ungodly strong with his right arm and that left stump. He could stab a transmission under a car by himself. He drove that car with his right arm crossed through the steering wheel to push the shift buttons. He raced it for alot of years at the local strip.
Sorry for the highjack but your project is bring back alot of memories.
Nolan

The weather has finally warmed up and yesterday I was able to get back out in the shop and do some work on the mock-up Valiant. Since I last posted I did find and buy the correct oil Pan (actually ended up with 2 of them). I also found a new oil pickup that should work. Over the winter I made a few decisions on how I was going to proceed with the project.

The first is the K member, for the non-Mopar types the K member is basically the cradle the engine sits on and the front steering and suspension bolt to. After studying the K member in the green car It looks like the original 6 cyl K member was replaced with a Direct Connection Big Block K member, (as far as I can tell the BB K members are no longer produced by Chrysler). As I’m planning building my motor mounts off the original slant 6 frame mounts, (which the K member in the Green car does not have) I’ll swap out the K members between the 2 cars hen I get to that point.

At this point I’ve got the engine pretty well positioned and the next step is to go underneath and massage the trans tunnel a bit for the OD unit on the 46RH.

It’s been about 5 months since I ran the engine for this project so while I was out in the shop I decided I’d go ahead and get it fired up and bring it up to operating temperature. That turned into pulling the carburetor apart to replace the accelerator pump……I’ve never seen one of the neoprene accelerator pumps shrink before but I guess its what I get for using one of amazon’s cheap kits. Fortunately I had a couple of new leather and brass ones on the shelf. Yeah I know they shrink too if they are left to dry out but at least they swell back to normal when they sit in gas.

That engine sure sounds good. It will be nice to get it in something and actually have it move under its own power.



CVC by M Patterson, on Flickr


I’m not sure if I ever posted this video here before but it’s the build and run video on the engine I’m using on this project. It should make just a nice reliable street motor. I still have to pull the intake to have the plenum divider milled for the Holley sniper FI I hope to eventually run and change the oil pan and pick-up out but that’s bit down the road.

https://www.youtube.com/watch?v=SzFdDWr1XcY



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The video is soooo cool! And the Hemi sounds GREAT! Thanks for posting.

That hemi makes some beautiful music! Like your engine stand.

“..….Like your engine stand……”

Yeah, I’ve always kind of had a love hate relationship with that run stand. I built it right after I got my first shop built (35 years ago). The tubing I had on hand was thick wall and it weighs a ton. I built it so I could run a bunch of different engines on it and that necessitated making it long enough to accept a bellhousing (primarily for the Ford and Chryslers that bolt the starter to the bellhousing instead of the block). There is also added length to accommodate a fan and HD fan clutch. Basically it’s heavy and takes up a lot of real estate. Add to that were all the bellhousings and flywheels/flexplates I ended up keeping on hand. It eventually ended up out in the storage shed out of the way. Over time a lot of the pieces were stripped off of it for other projects until I decided to build the HEMI and it moved back into the shop and I got to replace all the parts I had swiped off of it.


The favorite stand I built is this one.


cade stand by M Patterson, on Flickr

I built it for small and big block Chevy’s. The radiator and control panel were made to be removable with a few bolts so it could be used as a compact storage stand. I’d always kind of thought I get around and built a second stand but someone came along and wanted it worse than me so I sold it.

I got to admit a run stand is sure nice to do the cam breakin and take care of any issues that may show up. It's nice to know the engine will start and not leak when it goes into the car.


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