Hi--this is my first thread on this great forum.

I just bought a 1950 EL which has had a number of engine parts replaced over the years ( it's now essentially a 74"-er with all of the changes). How do I interpret the #'s on the jugs and heads to determine exactly what years these were from?

Also, were all externalpanhead parts ( ie jugs and heads)from '48--'55 perfectly interchageable without modification?

I'm considering replacing the old-style plumbing-fitting style manifold heads with the later O-ring style heads. Are these later heads interchangeable with those on a 1950 model?

Thanks in advance!

 

OK--let me narrow this question down. Which year(s)panhead heads are interchangeable by just bolt-on swap. I have a 1950 which is equipped with custom, dual carburator heads ( one-of-a -kind set up) and I want to swap this set up out for a stock, single carb heads. Any advice would be appreciated.

 

Doc...

CYLINDERS

Outside of 61 and 74 bores, there are three styles of cylinders for 48-65 motors. All 48-65 OHV cylinders have a lip on the top of the barrel to fit into a recess on the head. All 48-65 OHV cylinderrs have at least one oil passage. Front and rear cylinders have different fin configurations to clear the push rod covers and are not interchangeable.

The first style of cylinders is used on 48-52 motors and have a feed oil passage on the right side and a return iol passage on the left side. The return passage on the left side went straight to the cylinder base where it met the crankcase return oil passage in the crancase. There are no other oil passages in the cylinder.

The second style is used on 53-62 motors. They have a feed oil passage thhe same as above HOWEVER, while the return oil passage goes all the way to the bottom of the cylinder, there is another hole near the bottom of the cylinder in the bore that connects with the oil return passage. The return oil in these motors drains into the cylinder bore providing extra lubrication.

Note: parts books show separate front and rear cylinders w/ pistons for 55-62 models. These are the same cylinders used in all 53-54 OVH motors and 55-62 FL motors. Only the pistons are different.

The third style of cylinders is used on 63-65 OHV motors. They have the same style iol return passage as the second, however they do not have an iol feed for the rockers...it is now taken care of by an external rocker oil line.

Last thing about cylinders...MoCo stamped them w/ month day and year ex: A 13 9 would translate to mean Jan 9 1949. They skipped the letter "I" becuase it could be confused w/ "1". Aftermarket cylinders lack the stamp and it is the easiest way to distinguish OEM or not.

HEADS

There are three styles used...'plumber nut', 'O-ring', and 'overhead oiler'. Plumber nut was used on 48-54 style heads; O-ring style were used on 55-62; overhead oilers were used on 63-65 heads.

There are at least 8 different sets of heads 49-64, three of which are for 55-65 OHV motors only. 48-49 use the same heads. The heads have seven main cooling finsand six secondary cooling fins under the rocker cover, plugged holes near the exhaust portand casting numbers denoting front and rear as well as date codes.

50-54 heads are identical except for two things... they no longer have the plugged passages and the casting codes are different.

On some late 54 models, the new aluminum D for 55/later models was used. This was the six hole version.

Starting in 55 there were two different sets of heads produced, one for FL, one for FLH. he only difference is that the FLH had a polished and flowed intake port which meant they cost more.

55 heads are a one year only model. This is the first year for the new manifold, the six cover rocker mounting system, and different casting codes.

56-57 models received a little modifications...the number of cooling fins under the cover changed from six to nine, the d ring is agin modified to use 12 screws, the casting codes are again changed and are now on top rather than under.

58 to 62 heads have all the feature of 56/57 heads but the width of the cooling fins was increased and went from 3/32" to 1/8" at the tips. The heads have the same casting numbers as before.

63-65 heads are overhead oiler. They have large bosses between the two lower front fins that are drilled and tapped for outside oilers.


Sorry for long rant...but no short way to say it.

 

Wow--I'm awed by your knowledge, Panzforever! Thanks for the detailed reply. I'll keep this post handy and may consult with youin the future once I get started on this project, if you don't mind.

Q--what year o-ring heads could easily be adapted to the 1950 jugs--ie where the oil passages would line up properly?

 

doc...glad to help. herz what I'm thinkin 48-62 heads should pretty much be interchangeable w/ obvious exception of plumber/o-ring set up. I have a set of 56 heads that I will compare w/ my 49 heads cuz something in my mind sez that there may be a hole that should be plugged if later style heads are used on early jugs.

And most of my knowledge come from Al Hernandez, Sam Arena HD in San Jose (not there anymore.. he or the shop). Outside of that it come from riding pans since 1970, Palmers book on pans, Greg Fields book on pans, the Custom Chopper Cookbook (1981), Tech Tips by Jammer (1985), old HD service bulletins, tech tips from Easyriders (before they forgot who they were and where they came from), and a whole bunch of garage mechanics like you n me.

 

Thanks again, panz. I'd ideally like to install the o-ring type of heads on the motor.

 

Your not going to gain anything going to O-ring intake heads, either one will leak if not propperly built and checked, and besides all you have to do is change the intake nipples not the whole heads