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Replacement or rear crankshaft plug -- fixed pitch conversion

Bastien

Well Known Member
Replacement of rear crankshaft plug -- fixed pitch conversion

Hello,

I am currently finishing an RV-8 project that I purchased partially built.
It came with a Sensenich fixed pitch propeller and as I already have an 0 SMOH Lycoming IO-360-B1B engine set for constant speed propeller I would like to use this engine and convert it for fixed pitch propeller.

After reading the Lycoming SI 1435 I understand that to convert to fixed pitch I have to punch a hole in the rear crankshaft plug and install the front plug STD-1211. ( I have the setup as shown on Figure.1 of the SI)
https://www.lycoming.com/sites/default/files/Conversion%20from%20Constant%20Speed%20to%20Fixed%20Pitch%20Propeller%20and%20Vice%20Versa.pdf

However I would like to keep the possibility of going back to a constant speed propeller setup maybe in some years.
Is it possible to remove the rear plug and replace it without having to return the engine to Lycoming ? if so, does someone have the part number of this part ? I have been unsuccessful in finding it.

Thanks,
 
Last edited:
Crank conversion

You have a IO-360 B1B which is constant speed.
Refering to fil 1. There is no front plug on this engine because oil should be able to reach the propeller. The back plug forces the oil to return to engine via the prop governor oil line in front of the back plug.
When converting to fixed pich you install the front plug and remove the back plug. No oil line. Part nr for the front plug as well as back plug is found in fig 1.
It's easy to install or remove the front plug.
Removing and installing the back plug is somewhat tricky becase it is placed
behind the oil pipe (off centre mounted) inside the crank.
If something goes wrong working with the back plug you may end up removing the cranck for service. Getting help with this is a good choise.

Good luck
 
If you get a governor drive plate that has the small recess machined in it as depicted in the picture in the link below. ( A little hidden by the gasket...) You will be able to run fixed pitch without piercing the rear plug. Just install the front one and that gov. drive plate in lieu of the gov and you will be good to go FP. You have to leave all the rest of the CS plumbing on the engine for this solution to work. If you ever want to go back to CS just install the gov and remove the front plug and you are good to go CS.
Good Luck,
Mahlon
https://vansairforce.net/community/attachment.php?attachmentid=6739&d=1610148928
 
Last edited:
If you get a governor drive plate that has the small recess machined in it as depicted in the picture in the link below. ( A little hidden by the gasket...) You will be able to run fixed pitch without piercing the rear plug. Just install the front one and that gov. drive plate in lieu of the gov and you will be good to go FP. You have to leave all the rest of the CS plumbing on the engine for this solution to work. If you ever want to go back to CS just install the gov and remove the front plug and you are good to go CS.
Good Luck,
Mahlon
https://vansairforce.net/community/attachment.php?attachmentid=6739&d=1610148928

Mahlon,
Would you happen to have a P/N: or source for the governor drive plate?
 
Follow Mahlon

I would follow Mahlon’s advice. That’s what I did. I feel honored he used my picture of the rear cover. For me, the cover came with the engine from Van’s.
I think they are readily available from aircraft spruce, etc.
 
If you get a governor drive plate that has the small recess machined in it as depicted in the picture in the link below. ( A little hidden by the gasket...) You will be able to run fixed pitch without piercing the rear plug. Just install the front one and that gov. drive plate in lieu of the gov and you will be good to go FP. You have to leave all the rest of the CS plumbing on the engine for this solution to work. If you ever want to go back to CS just install the gov and remove the front plug and you are good to go CS.
Good Luck,
Mahlon
https://vansairforce.net/community/attachment.php?attachmentid=6739&d=1610148928

Thanks a lot for your guidance Mahlon,
I read about it somewhere but never found a picture of it :)
 
You have a IO-360 B1B which is constant speed.
Refering to fil 1. There is no front plug on this engine because oil should be able to reach the propeller. The back plug forces the oil to return to engine via the prop governor oil line in front of the back plug.
When converting to fixed pich you install the front plug and remove the back plug. No oil line. Part nr for the front plug as well as back plug is found in fig 1.
It's easy to install or remove the front plug.
Removing and installing the back plug is somewhat tricky becase it is placed
behind the oil pipe (off centre mounted) inside the crank.
If something goes wrong working with the back plug you may end up removing the cranck for service. Getting help with this is a good choise.

Good luck

Thanks for your advice, I indeed see that it is tricky to get in there but I can probably make a tool to get it removed. However I find no PN on fig.1 of the SI, only on fig 2 but that's for an other plug type.
 
Thanks a lot for your guidance Mahlon,
I read about it somewhere but never found a picture of it :)

I am about ready to run my new YO-360, and will be running fixed pitch. This engine like most is setup for C.S. operation, and the conversion is covered by a S.B.. The alternative method mentioned in the forums is nstalling a cover with the oil galley. My engine came from the factory with that SAME cover. It would seem my engine needs no modification?
Was it run in at the factory with a F.P. prop in it's current configuration? If I run a fixed pitch prop w/o complying with the S.B., will that void my warranty?
Any thoughts appreciated.
 
My first RV started life with a FP prop (new Lycoming engine from Van’s). I did the rear crank seal punch hole as listed with the manual that came with the engine.

At 300 hours I replaced that a prop with the Hartzell BS CS prop. The guy that help me had made a tool out of some galvanized pipe that had a slot cut in to go around the oil pick up tube in the crank. It took a few minutes to remove the front seal, then the rear seal that had the hole. This was done with a treaded rod that screwed into the rear seal hole, then a dent puller to remove the seal. The new rear seal was slide into place then two taps on the pipe tool to seat the rear seal.

So, find someone that has done this, has the right tools, and all is good.

Carl
 
If you get a governor drive plate that has the small recess machined in it as depicted in the picture in the link below. ( A little hidden by the gasket...) You will be able to run fixed pitch without piercing the rear plug. Just install the front one and that gov. drive plate in lieu of the gov and you will be good to go FP. You have to leave all the rest of the CS plumbing on the engine for this solution to work. If you ever want to go back to CS just install the gov and remove the front plug and you are good to go CS.
Good Luck,
Mahlon
https://vansairforce.net/community/attachment.php?attachmentid=6739&d=1610148928

I used this method with a B1B, it worked without any problems.
 
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