Could you guys please help, or tell me how to decipher the date code on a 400 that I have? I think it is out of a 70's 2 wheel drive truck. Code is DIAE-6015-A2C . I am trying to get an idea of its age.

Thanks!

 

That's just a part number.

Look at the back at the engine by the oil pressure switch. There you should find a logo that has "C" under "M". On that area. Around the area there is the date code - like 5A12.

 

I found the C logo, next to it is what looks like a plate with a flat head screw at each end that is actually cast into the block. On the plate it has the numbers 2E4. The 2 has two dots under it, thats all that is there.

 

should be May 4th 1972.

 

That's what it is. You found it!

2 = 1972

E = May (Month cast is by alphabet, so A = Jan. C = March, etc.)

4 = 4th day.

May 4th, '72, 5-2-72.

I'm told earlier 351M/400 blocks are inferior compared to ones after 3/76 cast date.

It was casted at the Cleveland plant (I think).

 

Thanks for the reply, do you know the specific problems with the early blocks? Is there an issue if I use the early crank and connecting rods to rebuild a worn out 351m into a 400?

Thanks again

 

The problems only exist on the block itself. Water jackets had a tendency to crack. This problem was solved in mid '77.

 

Thanks, I bought the 400 complete for 60 bucks to replace the dying 351m. I don't know if I should try it, it has probably over 100k on it, I would have to switch pans and sump pick-up as it was out of a 2 wheel drive. I was told it was running probably over 5 years ago, it is not locked up, but under both valve covers there is a ton of sludge build up, pulled the pan lower end is fairly clean and the cylinders don't look scratched up from what I can see from the bottom. Of course it would need a timing chain set.

 

the water jacket cracking problem only affected blocks cast at the michigan casting center before March 2, 1977.

 

Are you absolutely sure it's a 400? Not that it matters too much at this point... Only the crank and pistons are different between the 351M and the 400.

You ought to give it a compression test before you throw it in a truck.

If you don't see any metal shaving/pieces in the pan, then it should be OK. I'd check the valves. I haven't seen any untouched 351M/400 without sludge buildup. Did you pull up the intake manifold to see any sludge?

Buy an aftermarket three-way timing chain set and set it at 0, not factory -4. Should free up some muscle.

 

I am not 100% sure that it's 400, The guy I got it from said he was sure that it was, he mostly had 302's that he worked on, and seemed to know the engine lines. Are there any stampings that I could see on the crank? I haven't pulled the intake, I thought about leaving the engine on the stand turning it sideways and cleaning the heads with brake clean or gunk. It's got the old points dist. I understand that I could use the pointless one from the 351m. My real problem is my son needs sonething to drive quick. I have another 400 that is pretty much drop in condition with about 30k on it. It is for the other f250 frame that is in the driveway (that my wife isn't crazy about). I'm thinking that I should probably use the other projects 400 for now to get my son's truck going. Sorry to ramble on, I'm just looking for the quickest solution to get the truck going.

 

I think you can check the crank to see if it's a 351M or 400 crank. Don't hold to my word.

Yes, you can use the DuraSpark from the 351M. It will bolt up without issues. Just make sure to check the hex for wear.

I'd go with the drop-in 400 with 30k if your son needs something to drive as soon as possible. Why take chances?

 

I agree, as usual, I assumed the 400 that I bought was in better shape. The seller didn't make any false promises, 60 bucks is apparently what an engine to rebuild sells for in Ky.