1971 Cj5 Project- But Unsure Of Exact Motor

New to site and new to Jeeps (but not new to auto mechanics) I purchased a 1971 CJ5 “roller” project about 6 months ago. It look like it has had a few modifications along the way such as Muncie M20 4-speed and therefore some mods to the rear driveshaft. I’ve replaced all shocks, and just finished replacing the entire brake system with OEM parts. Getting trans & transfer case rebuilt currently, and about ready to start on rebuilding the engine. Engine was not in the Jeep when I bought it, and I now have it on an engine stand awaiting disassembly. So, not sure it’s an odd-fire 225 CI as originally thought. The current stock distributor has evenly spaced spark plug wire terminals, and not the uneven terminal spacing that I’ve seen. Intake manifold number is B-1378704-E, firing order 165432. The number on the back of the block is extremely hard to read - B375 82? (see pic). The number on the right side of block below spark plugs also doesn’t make any sense to me since I expected a long part #. Looks to be KM H and that’s it?

 

You see all kinds of combinations on these engines. You are correct about that not being the distributor for an "Odd Fire" 225, but it has the old style valve covers which I don't think will fit on 231 heads. Are you sure that is the distributor that goes to this engine?

It sure is a nice clean looking engine, are you sure it needs to be rebuilt?

I don't know as much about these engines as others on the site do, but if you pull the oil pan you can tell right away if it is an Odd Fire, or Even Fire engine by looking at the rod journals on the crank. The Even Fire has pairs of offset rod journals, an unusual looking crankshaft, but the Odd Fire rod journals are not offset.

 

B1375182 block casting was used on the 1966 Jeep and perhaps a while there after.
But it’s certainly not the original 1971 block.
The “M” indicates 1966 also.
The “H” indicates it was original with a 2 bbl carburetor.
Early 1966 were mono bore manifolds so this must be a late 1966 block.
I would certainly guess that manifold to be the original to this block.
Bottom line —- genuine 1966 225 Dauntless.

 

Thank you for the reply! Am I sure that’s the original distributor- No I am not…There’s been a few surprises along the way, but thankfully not too many! Since the engine was out already, I thought I would go through it to know for sure what I’m dropping back in. Yeah, I guess the crank journals will tell it all.

 

Oldtime knows a lot about these things, and he says it is a Dauntless engine which would have been an Odd Fire engine.

That distributor has me confused, as it doesn't look right for an Odd Fire engine which is what the Dauntless was. I am wondering if the wrong distributor would fit, if it would fit the engine wouldn't run right, if at all.

I do not know if an odd fire can be rebuilt as an even fire, but if it can that would require the even fire crankshaft, cam and distributor.

 

I see no reason to think it is an even fire distributor.
Looks like a normal odd fire Delco Remy to me.
Here is some info I posted not to long ago concerning Dauntless DR distributors…. What Distributor Do I Even Have?
The original distributor on your late 1966 engine would be a DR 1110342.

 

The only even fire 6 cylinder distributor that would fit would be an HEI. It's definitely not that.

 

Also note the points distributors dealt with the odd fire by having an elongated end on the rotor that got it close enough to the evenly spaced posts in the cap.

The HEIs are the ones with the weird wire spacing and strange posts inside the cap.

 

The only running odd fire I have owned had a different distributor than he shows, it had a larger cap and seems like the plug wires were oddly spaced. That was 30 years ago, and the engine was in a M38 I had. I only ran it a little before pulling it out and replacing with the L 134 I traded the V6 for.

The only other 225 I have owned is disassembled out in the shed. It has a distributor with a wide base but has no cap.

 

Guys, thanks for all of your comments. Educational moment for me. One basic comment that I can not wrap my head around is the odd-fire design! Three journals on the crank with a 90-150-90- 150 etc timing duration. So if each cylinder needs to fire at “odd durations” (not an even 120 degrees), then how can the distributor terminals be evenly spaced? Wouldn’t cylinders be grossly firing at the wrong times? And why then would an upgraded HEI distributor be oddly spaced to properly fire the same engine? What am I missing? I’m losing sleep over this…Help! lol

 

This link was from an older post asking the same question regarding a KM H stamped engine.

What year is my Dauntless ? | ECJ5 (earlycj5.com)

Buick 225/231 V6 Casting Numbers, Internal Specs For Most Years and Notes « Earlycj5.com (archive.org)

 

This explains how the cap is able to have even spaced towers….

 

I went out into the shop to take some pictures and make it more clear. (...and oldtime just beat me to it.)

This is the points type distributor (Delco in this case) with evenly spaced posts on the cap:


Inside, the posts look like any normal dsiributor:


But... The rotor has a very wide tip at the end of it. This means even though it's not exactly pointed at the post, the electrode still overlaps the proper post thanks to the wide tip:


They solved the same problem differently with the HEI odd fire distributors in the 70s. They used a V8 cap casting and left two blank posts. However, if you look at it, it's not arranged in 150-90-150-90-150-90 spacing either. 4 are close together and then 2 are close together:


How did they solve it this time?

They have long offset electrodes inside the cap to translate the proper rotor position to the proper post:


In this case there is a standard narrow tip on the rotor:


Why did they do the trickery with the rotor on the early ones and then with cap on the later ones? I have no idea.

 

On a points ignition, when the coil is fired is controlled by the points. Which cylinder the spark jumps to is controlled by the rotor and cap. To accommodate the difference in top dead center between cylinders the rotor tip is elongated as shown by others.

 

Just think of this V6 kind of like a V8 with two cylinders lopped off the back. Run through the V8 firing order, only missing 2 firing events. This is not exactly what the Dauntless is, but each set of rod journals are shared on each crankpin for the left/right banks and this is a 90 degree block. The later even-fire version actually has two offset journals on each crankpin to make a consistent 120 degree even firing order for the 6 cylinders.
Your engine looks pretty fresh. I would pull a valve cover, and maybe the oil pan for an inspection, but wouldn't be suprised if its already been refreshed/rebuilt.
When you get your Dauntless running, you will know its an odd-fire. They have a very unique exhaust note.
I too have a Muncie M21 in my '66. Some folks don't care for the rear/left offset shifter, but they shift so nice with a Comptition Plus shifter. I prefer it to a cane shift. My transfer case is very close to the stock location so has both stock length driveshafts.
-Donny

 

That HEI distributor is what was in the 225 I had in that M38, and thanks guys for the explanations about the points distributor. That makes sense to me now, and I apologize for any confusion my comments may have caused Mr. Myers.

That engine being so clean makes me think it was already rebuilt, and were it mine I would want to hear it run before deciding to tear it down.

 

Yeah, that makes sense and I might do that. Take a quick peak under the valve covers & oil pan and see what it looks like. Thanks.

 

Now it all makes sense, so thanks for all of the pictures! Took a look at my rotor this morning, and it’s definitely Odd-Fire 100% .