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Newbie with some basic questions.


motoMark
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Hi Everyone,

I just picked up this 1951 Plymouth Cambridge this weekend and have some basic service questions. In an earlier life I was a professional auto mechanic so I know my way around a car pretty good, but an early 50's car is something new to me.

 

After I got the car home I figured I'd start with checking the basics. The bias-ply tires looked a little low so I checked the pressure. About 22 psi in all 4 so I inflated them up to 32. When I took it for a ride afterwards, I noticed it seemed to be more sensitive to imperfections in the road and would get jerked around a little when hitting a patch or groove in the road. When I drove the car the 90 miles home @ 22 psi, I did not notice that. Is it common on these old cars (and bias-ply tires) to reduce the tire pressure for better handling?

 

The engine oil looked pretty dirty so I wanted to get that changed right away. But I didn't know the oil type or capacity. Fortunately, a service manual was included with the car and I was able to get the oil capacity and recommended oil viscosity. I'm guessing it's a copy of a period manual because it recommends 30W oil for the summer. Is that would I should use, or would a 10W-30 be fine?

 

Thanks

1951 Plymouth Cambridge.jpg

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Wow, you are going to get a lot of different opinions.

 

Tire pressure, I go for 35 on my 51 Cambridge, but I am running radials.  Boas plies do tend to wander a bit specially if you have rain groves or the rod has any sort of rut in it.  This is why I don't run bias plies anymore.  Alignment, especially caster, can aggravate it.

 

Oil, I run 10w30 detergent oil, been running it that way since I bought it.  I usually add a quart of Marvel Mystery Oil in place of one quart.  There are those that will insist that you run 30w non-detergent oil because of sludge build up that may, or may not be there.  I'd get me one of the USB bore scopes and run it down the oil fill tube to look around if I was worried about it.  Multi wieght oil didn't get developed till 54, in the 55 service manuals 10w30 is what was recommended.  Don't have an issue with multi weights.

 

BTW, sweet looking ride.

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After engine has been broken in can a full synthetic or synthetic blend be used instead of 30W? Synthetic just seems to be far superior oil than the regular stuff. The engine would have had no time to build any sludge and an oil with detergent should have no effect I am assuming. 

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The Service Manual calls out 24 psi for the bias-ply tires. Yes, these tires tend to 'track' irregularities in pavement, a characteristic that can be a little spooky for folks who have never driven anything other than radials. But that's the way it was back in the day.  :)

 

You have a beautiful car...enjoy!

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2 hours ago, Marcel Backs said:

After engine has been broken in can a full synthetic or synthetic blend be used instead of 30W? Synthetic just seems to be far superior oil than the regular stuff. The engine would have had no time to build any sludge and an oil with detergent should have no effect I am assuming. 

 

Yes, although synthetic has higher qualities under extreme heat or cold, it may come with other unexpected qualities. I have experienced additional oil leaks and more oil entry into the cylinders (burning oil) when using synthetic oil in other older vehicles. I see no reason to run it in a flathead engine. I run a thicker detergent oil for the dog days of summer. The typical flathead engine is a far cry from high performance and extremely tight tolerances.  Non-synthetic oil will be just fine if oil changes are done at regular planned intervals when using a vintage car for typical driving.

 

If I were going to the Arctic in January, or the equator area in June towing a trailer, I'd certainly consider running synthetic oil under those conditions.

Edited by keithb7
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One question that has not been asked, does the engine have an oil filter attached to the engine block? It could be in a metal canister inwhich there would be a large nut on the lid that you unscrew and then can take out an oil filter you can get replacement filters at Napa. or does is have a metal lokking can that the line thread into at the top and bottom of the metal housing. these are the throw away style and are good for 8k miles but these can are getting expensive.

 

Can you post a picture of the engine compartment and then we can tell which type of oil filter that might have beeninstalled.

 

Rich Hartung

Desoto1939@aol.com 

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The first thing I would do is pull the oil pan and clean all the junk out. While doing that, pull the side covers and clean the junk out of the little oil "pools" that feed the lifters. Junk gets into those pools and can starve oil from the holes feeding the lifters. Then button up the engine and add oil.

 

If you really want to clean the thing out, add oil after the above and add some Amsoil engine flush, a couple of times if the engine is really dirty.  I have had good luck with it in cars that have sticky hydraulic lifters and rings that are not moving due to junk in the lands. In fact Amsoil instructs you to use it if switching to synthetic oil.

 

James

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For tire pressure, I was always taught that the air carries the load.

The load rating on the side of the tire is listed at X amount of weight at MAX air pressure.

Just saying if the tire states 32 psi, that is the max amount & not what is required to operate the tire.

 

Think of a 2 ton chain hoist, You can lift up to 2 ton, not required to only lift 2 ton. ..... Same with your tires, up to 32psi, not required to run 32psi.

 

A single seater bob tail roadster with the same tires would be a lot lighter, maybe 18 or 20 psi would be all that's needed to carry the load.

Your 4 door passenger car would require more air, how much there simply is no right or wrong answer.

You will need to play with it & decide what air pressure works best for your car's weight.

 

Just throwing out a idea, your car looks pretty decent. I imagine the previous owner took real good care of it.

I would further guess that all 4 tires at 22psi was not a accident. The previous owner experimented & found that was what worked for themselves.

I would put them back to 22psi, then try 24 or 26psi experiment & find where you like them.

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I find the old style skimny bias tires at low 20’s psi tend to fight me on the twisties.  I up’d the pressure to 30 psi. She does follow the road seams like a trout up a stream.  But I am ok with that. I push her pretty hard up a twisty road home. So 30 psi it is for me. 

Edited by keithb7
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My 1939  Desoto according to the owners manual states 28 lbs in the tire and I am using Bias Ply tire the Goodyear Airtire. So when running inthe summer the heat will increase when running them.  Yes Bias Ply will pull when the roads have been cutdown to be repaved so you have to slow down also when crossing teel open grate bridges.

 

I have owned my 39 for 35 years so I am accustomed to these situations.  The younger guys never grew up on bias ply tires they had polyester belted tires and then they radials so this is a learning experience for them.

 

Lot of owners go over to radials for the old cas, but the AACA does not permit them on cars that did not have radials. Their reason is that the geomety and the suspension on these older cars is not setup to handle the rolling action or sideway action of the radial tires. This is a major deduction if you are having your car judged. If you have a driver and then want to switch to radial to make you feel better than thats you option.

 

Rich Hartung

desoto1939@aol.com

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Thanks everyone for your feedback.

 

For the tire pressure, I just went by the max pressure on the sidewall (which I typically do on any of my cars).  Los_Control, I think you're probably right about this and will have to experiment with the pressures to find my happy place.

34 minutes ago, Los_Control said:

I would further guess that all 4 tires at 22psi was not a accident. The previous owner experimented & found that was what worked for themselves.

I would put them back to 22psi, then try 24 or 26psi experiment & find where you like them.

 

As far as the oil goes, I'll take everyone's opinions into consideration before I decide what to do. Since the car has only 29K miles and has been very well cared for, I'm hoping there is no "junk" in the pan or the side covers. For now, maybe I'll just do a basic oil change and run her like that for the rest of summer, while keeping an eye on the oil color as the miles tick by.

 

Another question about the oil change. The car has a filter housing that holds a cartridge and when I pulled the cover off the housing was filled with oil. Is this normal? The housing has a small metal tube running from it's bottom to a fitting in the side of the block, which I assume dumps the oil back into the pan. Could the tube be plugged?

 

Thanks again.

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Nothing stirs up more debate on auto forums that oil.   IMHO, any major brand of any viscosity that you purchase today will be superior to the best when the car was new.

 

I personally use 10w30 in older engines in good condition.   Oil burners or engines that demonstrate lower than normal oil pressure would get 15w40, normally used in diesels. Only in weather extremes would I use synthetic. 

 

It is normal for your filter to be full of oil.  It is prevented from draining by the valving.

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The opinions on oil is as many as choices of oil.

I think something important to remember, when the car was built. They did not use detergent oil. The car only has 29k miles ..... incredible find.

The oil canister is not a pressurized system, it is a bypass system where just a small percentage works it's way through the filter. Better then no filter but not ideal ... And was a option on many vehicles back then.

 

My point is, just for general maintenance it may be a good idea. to adjust the valves. 29k miles may be early, but 50 years may be overdue?

The idea is when you open the side covers, You can see how much sludge is already in the motor. Then you can decide if you want to drop the pan & clean it.

I know with my truck is simple to drop the pan, I think the cars are the same?

 

The reason why to be concerned, once you start using a modern detergent oil. It can clean and wash all the sludge & clog the pickup screen on the oil pump.

I think any modern oil is better then what was available years ago.

 

Is the motor clean inside? Did the previous owner already deal with this problem? A simple valve adjustment will give you a really good clue of what the rest of the engine looks like.

 

We love Kieth, he makes some great teaching tools. The model & year is different, but the procedure is the same.

 

 

 

Edited by Los_Control
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1 hour ago, Sniper said:

That Castrol seems to be available at Walmart, $22.47 at mine. 

 

I've only seen it the one time at my local Walmart. I ordered 6 qts from Walmart.com once and it was shipped from five different stores all over the eastern US, I can't imagine what they spent on shipping. It's easier to just have Amazon drop a couple jugs on my front porch with free shipping. I used to use Valvoline VR1 racing oil for the higher zinc load but the Castrol is considerably less expensive.

Edited by Sam Buchanan
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Walmart says two of my local superstores have it in stock.  But that means going to Walmart .... and running 20w50, lol.  Same price as Amazon though, so that's a viable option if time isn't important.  Geez, I remember when Walmart opened it's first store here.  Now they have 5, three super centers and two neighborhood markets.  Sorry, tangent of which I am a master.

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After work today I stopped at Advance and picked up 5qts of non-synthetic Castrol 10W-30, but thanks for the heads up on the High Zinc oil. What exactly does the added zinc do for the engine parts? I'm assuming better wear protection but wouldn't a regular high quality be sufficient?

 

Also, how does one drain the oil from the filter canister housing?

IMG20220725205320.jpg

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24 minutes ago, motoMark said:

After work today I stopped at Advance and picked up 5qts of non-synthetic Castrol 10W-30, but thanks for the heads up on the High Zinc oil. What exactly does the added zinc do for the engine parts? I'm assuming better wear protection but wouldn't a regular high quality be sufficient?

 

The extra zinc is recommended for engines with mechanical (flat) lifters because it offers better wear protection for the hardened surfaces. I've used such oil in all the flat tappet engines I've run for several years (Triumph TR6, aircooled VW's, the Plymouth).

 

Will a good conventional oil work ok? Sure, and with the low mileage we accumulate in our low-power engines it will probably be as good as the high zinc options. The cheapest house brand oil you can get at a 7-11 will be vastly superior to the oils our cars used in the olden days.

Edited by Sam Buchanan
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