My dad and I recently purchased a 71 Mustange convertable for a project car. When we bought the car (back in March) the previous owner told us that the engine was an H code Cleveland from another Mustang ('71 or '72). However, when we went to fill it up for the first time we weren't sure if it took unleaded (which I now know if should) or leaded. We called the guy and he said that he has always run unleaded. Now there was a lot of shady stuff on this car, so I wouldn't be surprised if the engine was not what he said it was. Here's my question: Are there any casting number on the block that can be used to Identify it as an H or M code engine (It is definitely a Cleveland, and not a 4bbl). Sorry for the long post.

 

The intake should have some, along with the heads. If you don't see any on the outside, take off 1 cover and look inside. There's one on the block too, but I'm not sure where to tell you to look. Welcome to the forum.

 

Where can you buy leaded nowadays? You can hope the exhaust valve seats are steel, but can't be sure without a reciept or inspection. If not, they will eventually let you know all by themselves...

 

You can't buy leaded anywhere (at least not to my knowledge), but you can buy lead substitute additives. The previous owner was a complete tool and had no record of (or knowledge of) any head work.

On a related note, Edelbrock now makes heads for 351 Cleveland engines. Not sure if that is old news, but I was super excited to find that. Check their website for more information, ther is a link right on the front page. mmmmm.... 456HP....

 

It looks like you answered your own question as to the type of engine. (It is definitely a Cleveland, and not a 4bbl) and that would make it an H code. I think the F code was a 302. You are right that there are casting nbrs to identify both the block & heads as to its type. I'm sure someone here can shed some light.

You should be fine as long with a 71 or newer engine as far as using unleded gas. That's all my 73 Clev has ever seen since I bought it in 77.

Anybody know what year Ford started using the hardened valve seats in their cylinder heads? I'm thinking mid-late sixties.

 

I'm just worried that it may be an M code... a P.O.S. later model psudeo Cleveland engine. I Just want to know what I'm working with.

 

Last time I asked their sales guy, he had no clue about any details about these heads, which sound killer. Its about time!

 

Here's a site that may help ID your engine...

http://home.comcast.net/~jelerath/mu.../heads-fr.html

This link shows an example of the type of head stamp:
http://home.comcast.net/~jelerath/mu...eng-id-fr.html

That should answer your question & has some interesting Cleveland info as well.

 

FYI:

As far as needing hardened seats goes on pre 76 vehicles, you don't need to worry until you do a valve job. There is enough "lead" pounded into the seats to keep them going for the life of the valve guides at least.
If you cut the non hardened seats you take away the lead coating, and then you will eventually have valve recession (but even that takes time if you don't have pre-detonation).

I ran a truck engine a little over 100,000 miles under some pretty stressful conditions with the non-Stelite (sp?) seats after doing a quicky valve job at 200,000 miles. Rings finally wore down to nothing ( I mean like about 22 gauge wire!) and it started consuming oil. I guess 300,000 miles for a work truck is fairly reasonable, so we went ahead and rebuilt it.

Darned thing is still going strong, gotta love those old Fords!!!!!

 

Thanks for the info Scott. Now you have me wondering about my 73 Cleveland seats.

I have read that the 351M & 400 were introduced with hardened seats. I thought I remembered seeing that 71 & newer 351C's were also made with hardened seats. I can't remember exactly where I got the latter from though.

Do you have the site that tells which years started using hardened seats? I'm sure that would clear up questions a lot of us may have.