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Chrysler M47S rebuild info.

Kurt0690

New member
My first post.
I really have enjoyed reading about everyone’s knowledge and experiences. On all matters and issues.
I’m buying a 1953 Century Resorter. I’m going to fully restore the boat and want to keep it as original as I can but being a muscle car guy I also want to do what I can to get more horse power and torque as well as the best prop possible. I also heard that I need to have the valve seats made out if stainless to allow for today’s unleaded fuels. It’s a 70 year old straight 6 but I hear it’s also pretty damn stout.
I’m open to any and all suggestions from port and polish to carbonation. It has dual carbs.
I’m an outboard guy so I understand horsepower and prop pitch for upper and lower end performance but this will be my first full inboard tackle. This boat will run 30 mph I’m sure but I’d be fully happy if I could get to 40 mph.
Thanks all
 
Are either of these engines similar to what you have?



klc.jpg



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Those are flat head engines.
The cylinder heads have no moving parts within them.
The intake and exhaust valves are in the cylinder block (off to the side of the cylinders) and are vertical with the faces aiming up.
The chamber area where the valves are (and the clearance above them) increase the combustion chamber volume.
This offers an undesirable place for the flame front to hide during combustion.

Short of porting work, flow work, enlarging the bores, increasing compression, etc...... I don't know what you could do in order to safely increase the performance of an old flat head engine.


flat head engine.jpg


 
Much appreciated. I understand.
I don’t want to create more issues with going forward either. Like you said it’s a flat head. Very simple. I believe you’re correct about just opening the ports and maybe get better flow from both intake and exhaust but I think I’ll stay away from doing anything too radical.
Should I run a lead additive or is it safe to run today’s Non Ethanol fuels?

Thank you too all. Good stuff here.
 
Much appreciated. I understand.
I don’t want to create more issues with going forward either. Like you said it’s a flat head. Very simple. I believe you’re correct about just opening the ports and maybe get better flow from both intake and exhaust but I think I’ll stay away from doing anything too radical.
Should I run a lead additive or is it safe to run today’s Non Ethanol fuels?


The lead additive (“Tetraethyl lead” ) was used in gasoline (back when this engine was produced) as to help reduce engine knocking (by increasing the octane rating) and to lubricate valve seats as to reduce wear.

Here is an interesting article to read.

http://www.todayifoundout.com/index.php/2011/11/why-lead-used-to-be-added-to-gasoline/


How deeply are you going into this engine?
If deep, perhaps talk to a good machine shop owner, and see if hardened valve seats can be installed in this cylinder block. I know that it has been done before with other flat head engines.




Have the engine dialed in for #1 cylinder @ true TDC, and have the timing marks verified.
See if they can degree index the flywheel and give you some sort of ignition timing reference points.

While it's doubtful that you could find an ignition advance curve for this 1953 engine, it would be great if you could so that you can pay close attention to the ignition timing.

I would also suggest using a high octane gasoline in this boat.
If you can avoid detonation, a bit more ignition advance can be used, giving this engine a bit more power/torque.


Goo luck.



 
Thanks again Rick.
That was my main question. Hardened valve seats.
I will go through the whole engine. Check for crank play and get new valves. All the way. I get what you’re saying about the timing too.
I also want to get away from a points ignition. I’m not sure If I can get a kit for that old of a motor but I’ll look into it.
I’m in a bad reception area but will check out the link you sent later today.
I really appreciate the advice and information.
Ill let you know what I find.
Have a good day buddy.
 
RicardoMarine said "While it's doubtful that you could find an ignition advance curve for this 1953 engine", I have a clean copy of the factory maintenance manual. On page 107 it states:

Governor Advance M-46, M-47
Degree of advance Distributor--Distributor RPM

0---------------------------- 350
3---------------------------- 400
5---------------------------- 700
7--------------------------- 1000
9--------------------------- 1300

Keep in mind the distributor turns at half the crank speed.

 
Thanks again Rick.
That was my main question. Hardened valve seats.
I will go through the whole engine. Check for crank play and get new valves. All the way. I get what you’re saying about the timing too.
I also want to get away from a points ignition. I’m not sure If I can get a kit for that old of a motor but I’ll look into it.
I’m in a bad reception area but will check out the link you sent later today.
I really appreciate the advice and information.
Ill let you know what I find.
Have a good day buddy.

I don't know much about these engines.... but you are welcome.
Out of curiosity, I will stay tune in to this thread!


As for going to electronic ignition triggering..... I think that you'd be hard pressed to find anything that would work with that early system.
You may be able to modify one of the Pertronix kits, although I don't care for how Pertroix uses Hall Effect triggering.


What you have now is a Kettering system..... i.e., contact points, invented years ago (1912 or so) by a man named Charles Kettering.

Use a dwell meter when adjusting the points for the correct dwell angle, and you will be OK.
 
It is generally true that four stroke cam shafts and distributors run at half of crankshaft speed, as the valve moves and sparks for a given cylinder occur every other rotation of the crank. But just to screw that up, there are a few oddballs that run the ignition system at crank speed and have a spark at the end of the exhaust cycle. This is known as a wasted spark system.

Most lawnmower type engines have a wasted spark design, so they can run the ignition off the crankshaft under the flywheel.

https://en.wikipedia.org/wiki/Wasted_spark
 
.....
RicardoMarine said "While it's doubtful that you could find an ignition advance curve for this 1953 engine", I have a clean copy of the factory maintenance manual. On page 107 it states:

Governor Advance M-46, M-47
Degree of advance Distributor--Distributor RPM <<<< These are key words!

0---------------------------- 350
3---------------------------- 400
5---------------------------- 700
7--------------------------- 1000
9--------------------------- 1300

Keep in mind the distributor turns at half the crank speed.

Easy to convert:

0---------------------------- 350 actually = 0 @ 700 crankshaft RPM
3---------------------------- 400 actually = 6* @ 800 crankshaft RPM
5---------------------------- 700 actually = 10* @ 1,400 crankshaft RPM
7--------------------------- 1000 actually = 14* @ 2,000 crankshaft RPM
9--------------------------- 1300 actually = 18* @ 2,600 crankshaft RPM

What's missing is the BASE advance value. Once the BASE advance is known, that would be added to the progressive value.

Basically, one could plot out a curve graph with the numbers above.



Rick this is good stuff.
I did not know about the half speed rotation.
Thank you. This has been good.

It is generally true that four stroke cam shafts and distributors run at half of crankshaft speed, as the valve moves and sparks for a given cylinder occur every other rotation of the crank.
That is concisely true for a 4 stroke engine.

But just to screw that up, there are a few oddballs that run the ignition system at crank speed and have a spark at the end of the exhaust cycle. This is known as a wasted spark system.
Most lawnmower type engines have a wasted spark design, so they can run the ignition off the crankshaft under the flywheel.
Same with twin cylinder 2 stroke snowmobile engines.
However, that would not apply to this 1953 engine.


https://en.wikipedia.org/wiki/Wasted_spark
 
Rick,
I responded to your last send quite a few times but It never actually went through. Thank you so much for all of the information you’ve sent.
I’m actually heading out from Houston today to travel to Canada to pick up the boat and trailer. Gonna be a long but cool trip.
I will stay in touch after I return. Can’t wait to overhaul the motor and restore the boat itself.
Again thank you for all the links and all your knowledge.
Have a great day sir.
 
Thank you, and you are welcome.

I wish that I knew more about this engine.
I'll stay tuned in and see how you're doing as things progress!
 
A bit late to the party here, .... I have a pair of crowns in my boat. 265 CID, rated at 125hp @ 3600 RPM for the basic M47. From what I have read there isn't much you can do to get more out of these and still have good engines.
I have found some discussion about trying to get more out of these engines and why you can't here https://www.jalopyjournal.com/forum/



Mine...


enhance
 
Last edited:
From what I have read there isn't much you can do to get more out of these and still have good engines.
I have found some discussion about trying to get more out of these engines and why you can't here https://www.jalopyjournal.com/forum/E

The site wants me to log in.
Could you post the info for us?

As with most any Flat Head engine:

... due to the combustion chamber actually extending into the valve operating chamber, it offers a place for a portion of the flame front to hide. This causes the need for a very conservative ignition advance.

... due to the path of air/fuel and exhaust flow, the air/exhaust cannot be exchanged effectively.


None-the-less, what a cool old engine! :D

.
 
Sorry guys. Haven’t posted in a while.
I have my Resorter down here in Texas now from Canada. Can’t hardly stand it. She is in better shape than I ever expected. No rot. Planks although needing refinished are all still tight. I was thinking about rebuilding the motor as I had said earlier but after pulling the M47S and putting it on a stand she fired right up!! No kidding. Idles great. 50 psi oil pressure. Great response. The water pump even works well. I was amazed. I put in an oil treatment and ran the engine for about 4 strait hours. I’m sure my neighbors loved me hearing that nice deep rumble all afternoon. Guys I couldn’t believe how well she runs. It had tons of black flakes in the water ports but I used a pressure hose and flushed her out.
so all my earlier posts about rebuilding the motor are just me being proactive and worrisome. I’m ready to strip the engine paint and add new gaskets.
Any idea what the color code is for a 1952/53 Chrysler M47S is?
Im going to finish the engine then flip the boat and get started making a 5200 bottom.
all of you have been helpful. Especially Rick. Much appreciated.
 
Ned,
sorry I just saw your response too. Thank you for discussing.
I’m so happy with what I have that I’m not going to monkey around with the engine. It is what it is and it works well for what it is. I’m going to drive it around lake Livingston here in south Texas and be happy with it.
 
Hello again Ned,
I clicked on the attachment you sent. Good searches. Good stuff.
My M47S looks almost exact as your two. You even have the hydraulic transmissions like mine. What brand transmission is it? I’ve watched tons of YouTube videos from all the main guys and cannot tell.
I am going to keep the plumbing, oil cooler and water pump natural looking as well. I think it’s unique compared to the fully painted engines. I’m not sure if that is FACTORY or not but I like it. If I enter any shows down here I’m sure most of these people wouldn’t be able to tell the difference either.
I have many friends who I run with who think I’m crazy for getting rid of my 1969 Mustang Mach 1 for an old 53 Century Resorter. I bet I take the boat to car shows down here and still win awards after I complete her preservation.
 
Hello again Ned,
I clicked on the attachment you sent. Good searches. Good stuff.
My M47S looks almost exact as your two. You even have the hydraulic transmissions like mine. What brand transmission is it? I’ve watched tons of YouTube videos from all the main guys and cannot tell.
I am going to keep the plumbing, oil cooler and water pump natural looking as well. I think it’s unique compared to the fully painted engines. I’m not sure if that is FACTORY or not but I like it. If I enter any shows down here I’m sure most of these people wouldn’t be able to tell the difference either.
I have many friends who I run with who think I’m crazy for getting rid of my 1969 Mustang Mach 1 for an old 53 Century Resorter. I bet I take the boat to car shows down here and still win awards after I complete her preservation.
 
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