Help with ID'ing a Willys M38A1 engine

Randall · Post by **Randall** » Mon Jun 08, 2009 6:33 am

Gentlemen: I just purchased an M38A1, and the previous owner stated that the engine was not the original. The block casting numbers are: 646228-LW 10ANI-CR-N2. The numbers on the head are: 648830 (with a "2" centered below it), and 3-30, (with "WF" centered below that). Data plate on dash shows 2/54 for delivery date. What I'm wondering is: what year/model engine do I have? Is the tub a 1954 model year? Finally-can anyone tell me how to identify whether I have a IAD, IAY, or IGY distributor? I don't see any markings on the housing, but it's still connected to the engine presently. Any info would be appreciated! Thanks! <Randall>

Post by **wesk** » Mon Jun 08, 2009 7:44 am

646228-LW 10ANI-CR-N2

Is an early F head used in the Willys utility line and the 52/53 M38A1's. What are you serial numbers for the engine and the jeep? The M series Willys jeep went by DOD not model year. The 54 years would be Jan to Dec 54.

how to identify whether I have a IAD, IAY, or IGY distributor

There isn't any IGY, you are probably referring to the IGW.

Military 24 V waterproof IAU series original to the M38A1

Take a look at the illustrations of the distributors at this web site:
http://willysdistributors.com/_wsn/page2.html

IAD 4008, IGC 4705, & IAD 4041

IGW-4189

The IAT differs from The IAD in that it comes with a vacuum advance.
http://www.film.queensu.ca/cj3b/Tech/Distributor.html

Randall · Post by **Randall** » Mon Jun 08, 2009 3:45 pm

The data plate on my M38A1 has nothing stamped in the area that says "ORD. SERIAL NO."-it's blank. "MFR SERIAL NO." is 72005. "ORD STOCK NO." is G-2758-8358-319. The only numbers I saw on the engine were on the lower passenger side, and on the head, (the one's I included in the original message). The machined area above the water pump appears to be blank. Should I be looking elsewhere on the engine/body, or frame? It's been converted to 12 volts, and I'm going crazy trying to figure out what points, condenser, and cap/rotor to get for it!!!! The distributor looks like the IAD version that you sent to me, because it has the same fastening system for holding the distributor in place...as compared to the other ones. By the way, thank you for the all the info. you've sent me so far...you folks are great! <Randall>

Randall · Post by **Randall** » Mon Jun 08, 2009 6:52 pm

I just pulled the distributor. There is NO id plate on either side of it, however, IAT is cast into the underside of it. There is NO vacuum advance (place for a vacuum line) setup on it. The distributor is held in place by a single bolt that is upside down, and goes thru a mounting plate, like in one of the illustrations that you sent to me previously. Does that make sense? <Randall> On another note, the passenger side rear wheel well tag is intact, and says "SERIAL NO. 72005", so it matches the data plate.

Post by **wesk** » Mon Jun 08, 2009 10:09 pm

If you will post a photo of your distributor and a photo from the top with the cap, without the cap and without the cap and rotor we can probably sort this out very quickly.

The engine serial is usually very difficult to read and will be almost gone if the block was decked during a rebuild. Some solvent or lacquer thinner, a red or green Scotchbrite pad and some elbow grease should bring up some numbers.

I assume your 72005 is where the 19232 is on this dash serial plate. What is the date of delivery on your plate and does the rest of the data on this plate match yours?

This is the Willys Patent plate behind the passenger seat.

According to my data bases your MD72005 was a Feb 54 unit and the last owner was James Martin and it's original hood was 201001663. Did you buy it from James?

Randall · Post by **Randall** » Tue Jun 09, 2009 7:08 am

Wes...To answer your questions: The engine serial plate above the waterpump is now spotless, and there are no visible markings on it. I tried with bright light, dull light, indirect light...to no avail. It's smooth and clean. You are correct-I bought the jeep from James Martin. As for the data plate: My ORD. STOCK NO. is G-2758-8358-319. You are correct about my 72005 number as the MFR. SERIAL NO. My DATE DEL. is 2/54. Everything else looks like your data plate. How can I send you the pictures I took of the distributor? <Randall>

Post by **wesk** » Tue Jun 09, 2009 8:39 am

If you do a little searching there are several ways to determine what serial number was there before the block deck was reground. There are chemicals used by law enforcement folks and magnetic particle methods. Check with a local gun smith and see if they can help you with an ID of the missing serial. The old timers have dealt with ground off serials for years.

Looks like it is a IAY 4012 series distributor. Let me review the old Auto-Lite parts manuals I have.

Randall · Post by **Randall** » Thu Jun 11, 2009 3:42 pm

Wes---on this 134 c.i. engine....is the timing pattern 1-3-4-2? Is the front cylinder the #1 cylinder? <Randall>

Post by **wesk** » Thu Jun 11, 2009 9:40 pm

The front cylinder is #1 and the firing order is 1-3-4-2

Randall · Post by **Randall** » Sun Jun 21, 2009 8:50 am

Wes.....I'm having trouble determining when the #1 cylinder is at the top of the compression stroke. I removed all the spark plugs and tried to "feel" the compression when the #1 piston comes up, but it appears the valve clearances are way off...the valve cover was on finger tight, with no gasket installed, so it's obvious someone has been in there before me. From my tech manuals, it appears that there should be a timing mark on the front pulley and timing cover, but there doesn't appear to be any...not even a notch. I'm thinking that I need to adjust the valves to the proper lash first, then proceed with getting the #1 cylinder up on the compression stroke...before dropping the distributor back in. How should I go about adjusting the valves when the engine is cold? I think it said .016" of lash is needed on a hot engine. Any thoughts? Thanks for all the advice so far.... <Randall>

Post by **wesk** » Sun Jun 21, 2009 10:10 am

With the top and side valve covers off rotate the engine untill the #1 intake and exhaust lifters are in their fully retracted position. Now rotate the crank backwards one turn. Now place a screw driver in the #1 plug hole and slowly rotate the engine forward until the psiton upward travel stops. This should be TDC, Now check and adjust those two valve lashes. If they were extremely loose or overly tight then you should be able to rotate the engine by hand and feel when # 1 comes up on compression.