Jump to content

Wrist pin repair - 1929 Franklin 135

Recommended Posts

I am seeking advice in repairing a bad wristpin on the #6 cylinder of a 1929 Franklin Model 135 (Victoria).


1) Is there a source of detailed instructions to complete such a repair? 

--I do have the Parts and Owners/Service books for the 1929 Model 135, but it provides no detailed pictures or instruction.

--I also have the Dykes Automotive Encyclopedias from both 1929 and 1933, but these books do not provide a description nor drawings for this type of repair for the Franklin engine.


2) Is it possible or advised to complete this repair on the #6 cylinder (closest to the firewall) with the engine in the vehicle?


3) Does anyone have instructions or advice as to the steps to disassemble the #6 cylinder?

--Are there specific things to be aware of in disassembly and assembly?

--What is the best way to remove the valve assembly?

--Do the intake and exhaust manifolds need to be completely removed from the engine?  My engine has the heater box on the exhaust manifold, if this matters.


4) I understand I will need to have the cylinder checked for proper cylinder dimensions. 

--If the cylinder needs to be machined and a new piston installed........Is there a source for a proper oversized piston/rings?

--I am guessing the air-cooled engine requires a piston made of a specific metal alloy?


5) Are there additional questions that I am not asking?


Thank you for any thoughts or advice.





Link to post
Share on other sites

Jim, The problem you describe isn't too bad of job for a mechanic that has basic tools. If it was my car I would remove the manifolds and pull all the jugs off the motor starting with # 1 first and # 6 last. After you remove the manifolds , valve cage nuts at the base of the push rod tubes and nuts at the base of the cylinders , you can pull the jugs off in one assemble. Now you can have a look at all the pistons and bores. Where are you located? There are several good Franklin mechanics and  machine shops across the country that could help diagnose the problem.  

Link to post
Share on other sites



The 135 engine runs really nice, even though the Carter BB1 updraft carburetor that I purchased from the vendor in Ohio may not be a correct carburetor (There were no tags on the carburetor, when I purchased it).


At idle, etc, the engine seems quiet.


With a stethoscope, you can hear more noise in #6 than the other cylinders (at idle).


Under load or acceleration, it bangs quite loudly, but stops under deceleration or with coasting.


The vehicle had been in dry, proper storage in Burbank, California beginning 1976.  


I purchased the vehicle about one year ago, and it has been running (largely idling in my garage) since Sept 2014.


I would really like to get this vehicle out on the road, as we have about 360 days of sunshine and warmth per year.  Short drives in my neighborhood reveal this to be a really nice driving vehicle (This is my first Franklin experience).



Link to post
Share on other sites

If the #6 cylinder with the bad wristpin is out of round and must be bored, can someone provide a source for the correct oversized piston?


What is the maximum amount that one of the cylinders can be bored?


What type of metal alloy must the piston be constructed?


Would it be preferred to purchase a replacement cylinder in good condition versus boring the existing cylinder?


Are there other shop manuals (other than the Franklin factory and Dykes Automotive Encyclopedia) that might provide guidance for this disassembly/reassembly?


Thank you,


Link to post
Share on other sites

Hi Jim -

It sounds as if the best move is to pull the cylinder. Are you sure #6 is the one that bangs loudly under acceleration?

It could be one or more of several problems. Once you pull the cylinder, you will be able to find the problem.

The valve cage comes off easily after the two bolts up top and the tube clamp down below are removed.

You can usually pull the jug without disturbing the manifolds, but you might need to loosen one manifold to install a single cylinder.

With the valve cage off, remove the cylinder base nuts, plug wire, spark plug and run the piston to bottom.

You'll want to remove the hood and brace rod.

Sometimes it easiest to climb up on the hood sills straddling the engine and reach down and pull the cylinder straight up.

If it's stuck, you can run a couple base nuts back on a few threads, install the spark plug and hit the starter (ignition off!) to loosen the jug.

Once it is off, let us know what you see...

Feel free to call if needed


Tom Rasmussen

  • Like 1
Link to post
Share on other sites

Thank you, Tom.


The #6 cylinder is more noisy with a stethoscope on idle.  The hard banging or rapping only occurs on acceleration, as I have described.  Revving the engine in neutral does not give the same noise, although I have not listened with the stethoscope under those conditions. Perhaps, it is worth a try?


I will follow up, when I have the cylinder "jug" removed.


Thanks again.




Link to post
Share on other sites

 Hi Jim -


It's very helpful to perforam as many tests as you can before pulling parts off so we can zero in on the problem area.  A couple ideas:


Pull the spark plug wire at the #6 plug (and ground the wire) and then run the engine again and listen. Does the lighter noise at idle change? Does the lighter noise change when the engine is full hot vs cold?


Then drive the car with the wire off.  Does the banging noise change?


If the 'banging' does not change, try the plug wire grounding on each of the other plugs one at a time to see if the banging noise changes.  It is possible you have two noises in two different cylinders. 


I am less concerned about the #6 noise at idle and much more concerned about the louder noise.  The fact that you cannot get the louder noise to happen just revving the engine is a good sign. 


Keep us posted - 



Link to post
Share on other sites

Thank you, Tom.


I will try the things you suggest.


I will also run a compression check, as I have not yet completed that.


I should also note this is my first Franklin and my first experience with a car of this age.  Thus, I am not entirely certain of what noises are "normal", although I know the loud banging during acceleration should not be there.  I am mostly listening for significant differences among cylinders under different conditions.


I appreciate the advice and guidance.  I will update as I learn more.


Thanks again.



Link to post
Share on other sites


I ran the 135 engine (idling) to operating temperature and removed all plugs for the compression test:

Plug #6 - slightly wet; seemed oily versus gasoline; some particulates on the curved part of the electrode that looked more like carbon or soot than metal;  plug could be wiped off to look reasonable, BUT...the electrode tip was completely black across the firing surface.

Plugs #2-5 - all were covered with dry, black soot, EXCEPT the electrode tip on each plug was clean and shiny(no black soot or discoloration on the electrode tip); soot was easily wiped off.

Plug #1 - This plug looked somewhat "normal" without soot or black powder; electrode tip was shiny as with plugs 2-5.


**Please note the car has not been driven but mostly idled in the garage.  I do not know how much this (and, perhaps an incorrect carburetor) may contribute to the appearance of the spark plugs.


Compression test - 2 reading per cylinder, with the first reading after 4 engine rotations and the second reading after 6 engine rotations - I started the readings at Cylinder #6 to #5 to #4 to #3 to #2 to #1


Cylinder # 6        55 and 55

Cylinder #5         70 and 70

Cylinder #4         71 and 71

Cylinder #3         70 and 70

Cylinder #2         75/70 and 70 (3 readings - 2 readings with 4 engine rotations and 1 reading with 6 engine rotations)

Cylinder #1         72/74 and 74 (3 readings - 2 readings with 4 engine rotations and 1 reading with 6 engine rotations)


One other observation........Cylinder # 6 built pressure in almost equal steps with each engine rotation, whereas other cylinders jumped to approximately 60 with the 1st or 2nd rotation and then went to 70-75 on final 1 or 2 rotations.


I did go back and "spot check" the cylinder compression readings, even though the engine appeared to be quickly cooling.  The only difference was the #6 cylinder increased to 59/60.  All other cylinders tested between 70-74, as they did in the initial set of readings.


A final observation.....Using a stethoscope, the #6 cylinder is much more noisy than the other five cylinders, when the engine is revved from an idle (car is not moving).


Link to post
Share on other sites

Hi Jim,

I've been following this as I'm sure others have since it is winter for many of us and TALKING Franklins may be all we do for a few months! I'm really concerned with you trying to drive the car to further diagnose the problem. At this point we know there is a problem. It may be a "simple" problem now, but without KNOWING I don't recommend driving the car. I'm attaching a photo of my engine...It made a sound and I didn't get it shut down in time. I can't describe how quickly this escalated! The car then sat for a year and a half. I write this from heart. I will send you my contact information. I think my dad and I help you remotely.

Good luck, can't wait for you to get it on the road!



Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Create New...