Big Weekend with Improvements and Issues for my Valiant!

Friday night after work and dinner I pulled the Super Six carb off for a rebuild, I had to put the top piece on the belt sander because Gorilla Grip McGee rebuilt it previously and there was no way it was going to seal. After that I cleaned everything extra good and test fitted all the parts. I got it mostly reassembled up when I realized I left the fuel baffle on the workbench. It was late, 1:00 AM so I called it a night.

1967 Plymouth Valiant Slant Six Upgrades

Saturday after the Turlock Swap Meet I pulled it apart again, reinstalled the missing piece and plopped in onto the car. It quickly came back to life and we were off for a test drive. It was fine, scooted around great, but for some reason at 11:00 when we were leaving Dan’s house the floats became set too low and it wasn’t getting fuel to the accelerator pump well. Weird because it ran fine all over town during the day! Pull the top off again, adjust the floats, she fires right up and we go home!

1967 Plymouth Valiant Slant Six Upgrades

Check out the awesome brazing job the previous owner did on the FUEL line!!

1967 Plymouth Valiant Slant Six Upgrades

Sunday I organize all the parts I needed to do the HEI swap. Pull the old distributor, on slant sixes have a little adjuster piece underneath the distributor so I swap that over to the remanufactured electronic ignition distributor and drop it in.

1967 Plymouth Valiant Slant Six Upgrades

The rest of the installation is easy, I’d already swapped in a Summit coil, so it was just a matter of bypassing the voltage regulator, drilling a couple holes and screwing the used “High Performance” HEI module to the inner fender.

1967 Plymouth Valiant Slant Six Upgrades

I reused the old cap and rotor, which after close inspection was nasty and corroded, but I figured I could at least use it to get the thing going. The distributor was close to the I pulled it, so a few cranks and it fired right up. I set the initial to 10 BTDC, locked it down, and turned it off.

I told the little lady I was going out for a test drive; I was amazed at the extra pulling power over the points! Woo!! Pulled hard all the way to 4000 rpm where I shifted, I was happy as a clam.

I stopped at a hardware store for a couple bolts, came back out and that’s when the first sign of a problem showed up.

It cranked and cranked, probably for 30 seconds or so, and then fired right up.

I needed gas, so I stopped at gas station, after filling up I had a similar problem. I had to crank it for a while before it came to life, but it ran great once it did.

I get home, cook dinner and play with the kiddo before I get a chance I go back out to the garage.

I was able to duplicate the problem again, so I whipped out the volt meter. With the key on 12.3-12.4 volts to either side of the ballast resistor as well as both sides of the coil and leads up to the HEI brain module. The leads on the other side of the brain module only read 1.3 or 1.4 volts, but I’m not sure what they’re supposed to be, but at least there is some juice there.

Pulled a plug wire to check for spark, don’t see one, so next it’s to the coil wire. I see one strong blue spark, but it doesn’t spark as much as I though it would.

I get some fine sand paper out, sand the rotor button down a bit as it looks damaged and chunked a bit and the contacts for each cylinder.

I try firing it up again, it’s still a hard starter but it goes after futzing around with it a bit. I think maybe the timing is too advanced so I pull it back down to 0 BTDC like the factory suggests and lock it down, take it for a test drive. Still runs great, but I figure it was fine before, so I bring home and turn it off. Ten minutes later I go out and it fires right up. I’m content I’ve solved the problem; it’s around 11:50 on a work night so I call it quits.

Monday morning I go to start it, cranked it forever but it just doesn’t start. I’m dressed for work and don’t have much time to spare so I can’t tear it apart right then so I get into the “normal” and “reliable” family car and go to work.

After work I pick up a new cap and rotor did nothing, still no spark, so I started working my way backwards. The next problem could be either the brain module or possibly the pickup in the reman distributor.

The coil is a brand new Summit Racing one and it checked out okay on the ohm meter.

After a little research on the internet I learned that the HEI module cannot be field tested like other automotive electronics. I since I was getting current on both sides of it, I assumed it was okay… for now…

The last thing was the cheapo reman distributor. I find these instructions on the internet:

The two terminals coming out of the distributor read 291 ohms and the article states that “between 600 and 1,500 ohms is okay”. Ruh roh!

I read a little farther get to “if the gap is correct” part and realize I haven’t checked that yet.

The trusty Haynes manual comes out and I dig out the procedure, no more than 0.008 gap. Gotcha!

The 0.008 feeler gauge fits in with no tightness whatsoever! There must have been at least ten times the gap as required by the Haynes manual.

I set the gap correctly, button it back up, and with a twist of the key she lights off! Yay!!

A test drive revealed it ran perfectly still and started right up after sitting for a bit, and I was able to drive my little car to work on Tuesday and it felt great!

I’m going to replace the old spark plugs with the NGK ones, new drool tube seals, might try the extended electrode rotor along with opening up the point gap and put some advance back into the timing.

If you’re interested in trying this out on your own slant six click on the picture below to see the wiring diagrams in full size.

1967 Plymouth Valiant Slant Six Upgrades
Click Here for a Larger Picture!

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