Another 68 Plymouth question

[mac9128]

Just posted in the pcmo section about this for motor oil but also looking for trans and brake fluid recommendations for a 1968 Plymouth fury 3.

318 V8 automatic

Car has 93k. Sat more or less the past 15 years being driven maybe 1-3 times a year. Doubt either fluid has been changed in that time. Haven't worked on a pre smog car before so wanted to get some advice/tips from those who have.

The car sometimes stalls at very low speeds when turning in gear. Trans issue?

Thank you.

 

[dnastrau]

For the transmission I would use either Dexron III or ATF+4 since that fluid is supposed to be backward compatible with older Mopar transmissions. Make sure you drain the converter when you change the fluid and adjust the bands. It will probably take about 10 quarts to refill if you drain the converter. I'd drop the pan, drain the converter, change the filter, adjust the bands, replace the pan and put in about 8 quarts before starting the engine. The fluid should be checked hot idling in neutral - not park.

I would change the brake fluid with standard DOT 3 fluid.

The stalling issue is not likely the transmission. How old is the gas in the tank? Today's gas has a short shelf life and will eventually turn to varnish. Your 318 probably still has the original points and condenser distributor. Maybe it needs a good tune up?

Regarding octane: The 318 that year has a 9.2:1 compression ratio I believe. I would use at least 89 pump octane as a result to ensure that it does not spark knock.

I highly recommend joining this group as they only focus on C-Body Mopars and will provide lots of help with questions like these:

http://cbodydrydock.com/news.php

Congratulations on your '68 Fury III. I was brought home from the hospital when I was born in one of these cars!

Andrew S.

 

[zrxkawboy]

Excellent advice above from Andrew. The only point I would disagree on is the use of ATF+4. I would use a quality Dex III, although some prefer Type F in Torqueflites (for firmer shifts).

 

[artificialist]

If you have the engine stall as you steer your car, I would suspect that the idle speed is too low, and the carb and ignition need to be adjusted. You probably also have a maze of vacuum hoses which are failing and causing the engine to run excessively lean. When the car is in drive, and at idle, the engine is burdened by the torque converter, and when steering, it is more heavily burdened by the power steering pump.

I would look into enthusiast pages about what transmission fluid was used. Back when your car was built, there was basically Type-A and Type-F. Chrysler used one of those fluids, they never developed their own transmission fluid until the 1980s. Type-A was eventually replaced with Dexron and Mercon, and Type-F was still called Type-F.

Your car probably took DOT3 brake fluid, and I always prefer to replace DOT3 with a premium DOT4 because it tends to stay cleaner.

Given the age of your car, I would also consider replacing the gear oil in the rear axle. I'm not sure what viscosity you would need, check your fan pages. Have you removed the rear drums? Now would be a good time, as you may have an axle shaft leak or brake wheel cylinder leak after all those years. There would be no point in replacing the gear oil if the axle seal leaks.

 

[Chris142]

the stalling is possibly just a float level. shoulk be a very simple 2bbl carter carb as the 318 did not get a 4bbl till the late 70's

 

[drolds]

All the fluids need to be flushed, especially coolant and brake fluid. For oil, go with a quality 10W-40 or 15W-40 w/ engine oil flush before draining and using a few short OCIs. For the transmission, it should use ATF+4 which is an improved version of ATF+2 and ATF+3. The +4 additive pack is good for the older Mopar transmissions and will do the most to reduce torque converter shudder. Type F fluid is of no real benefit and has very different fiction characteristics from Dexron formulations including ATF +2, 3 and 4. The torque converter may have its own drain plug too. This car is a nice find if it is in reasonably good shape.
Avoid ethanol laced fuel as it will quickly degrade the carb. gaskets. If you plan to drive this car much, convert the points to a Pertronix system. This will be much more efficient & reliable than the old points and you retain the original distributor.

 

[SS1970chrysler]

I have a "few" of these cars and use a mix of 25% Type F and 75% DexIII for transmission and 80w-90 GL5 for the axles. I also use DOT4 or 3/4 for the brakes. At that many miles, you'd seriously want to replace the timing chain+gears and even clean out the oil pump pickup. A '68 is definitely a nylon gear unit. I only have one 318 (1972) and I'm already watching it carefully at 78k. Avoid aluminum contacts on the distributor cap and rotor as they fail faster. I'd use either an HDEO 10w-30 such as Rotella, or thicker. I haven't had great results with today's "Energy Conserving" 10w-30's in these older engines, except for I6's.
After sitting that long, you really want to check the soft plugs on the block itself. The rearmost ones on the sides and especially the two behind the flexplate are known to rust out.
You'll probably end up replacing the fuel pump soon.

 

[eljefino]

Originally Posted By: Chris142
the stalling is possibly just a float level. shoulk be a very simple 2bbl carter carb as the 318 did not get a 4bbl till the late 70's


Yeah this. Cursed Volares a decade later that were set up lean. Not enough gas in there= sloshing around. IIRC it was left turns that really knocked 'em flat.

 

[Lubener]

I had a 69 Fury 318/727 some years ago. Use 10-30 or 10-40 oil, DOT 3 brake fluid and Dexron 3 for ATF. I would do a full tune up including points and condenser. If that car sat for a long time with the points open, they are likely spent.Make sure idle is at 650 RPM. Don't overlook the mechanical fuel pumps on these.I would change it out since it is very old.Fuel from a bad one can get into the engine oil diluting it and will ruin the engine.

 

[Rat407]

Shouldn't he be using an oil that has a high ZDDP? Since it has a flat tappet cam.

 

[Chris142]

Originally Posted By: Rat407
Shouldn't he be using an oil that has a high ZDDP? Since it has a flat tappet cam.
i believe he should since my 3 LA engines ate a cam

 

[mac9128]

So is the rotella T6 5w-40 a good oil for this engine in terms of zddp content?

 

[440Magnum]

Originally Posted By: mac9128
Just posted in the pcmo section about this for motor oil but also looking for trans and brake fluid recommendations for a 1968 Plymouth fury 3.

318 V8 automatic

Car has 93k. Sat more or less the past 15 years being driven maybe 1-3 times a year. Doubt either fluid has been changed in that time. Haven't worked on a pre smog car before so wanted to get some advice/tips from those who have.

The car sometimes stalls at very low speeds when turning in gear. Trans issue?

Thank you.


No, not a trans issue. That car has no lockup clutch on the torque convertor, so it can't stall the engine.

Idle speed is too low, or the fuel level in the float bowl is a little too high causing a slosh to drown the engine when turning. Even a perfectly tuned carbureted engine may "fluff" a little rich and stumble during cornering because of the fuel sloshing around, and if the float is set too high it makes it worse.

As for oil and trans fluid, the 318/904 combo is about as forgiving as anything out there. It doesn't need massive amounts of ZDDP, and it doesn't need a 40-weight oil. Use a good quality 5w30, synthetic if you want to, but no need. The valve springs are not super-stiff, the cam is very mild, and LA v8's drown the cam in tons of oil, so its not starved for lubrication. I put over 400k on a 318 with a refresh at 190k (due to a broken cam gear- if it's never had a timing set, DO THAT NOW as the nylon cam gear can kill the engine in the blink of an eye). I always used 10w30, ending up with M1 for the last 150k miles until I gave the car away... still running well.

Trans fluid should be in the Dexron family, Dexron III is a very safe bet. ATF+4 is OK, but unnecessary as there's no TC clutch for the extra friction modifiers to work on. Dexron VI *should* work fine too, but I personally haven't tried it in an old Torqueflite yet. I'll go in my R/T or Polara on the next change, though.

 

[mac9128]

Thanks for your input