[DonJustham]

First thanks for all of the prior feedback. I followed what most of you suggested without taking the motor apart. I removed one of the valve cover gaskets and took photos of the lifters and guides. Have not

put it on a lift as of yet to find casting number near starter. What do you think, Boss or No? What should I do next to better determine?
Thanks Again

 

[DonJustham]

First thanks for all of the prior feedback. I followed what most of you suggested without taking the motor apart. I removed one of the valve cover gaskets and took photos of the lifters and guides. Have not View attachment 825900 View attachment 825901 View attachment 825902 View attachment 825903 put it on a lift as of yet to find casting number near starter. What do you think, Boss or No? What should I do next to better determine?
Thanks Again

Oh and it has a 2" wide harmonic balancer

 

[mustang_paul]

I‘m a little confused. The car in your last post was a blue 70‘. Now it’s a green 71‘.

 

[DonJustham]

I‘m a little confused. The car in your last post was a blue 70‘. Now it’s a green 71‘.

The blue car was one posted on craigslist that I was interested in and was purported to be a Boss 302. The 1971 green mach 1 is my personal car with a 351 engine in it and I have been trying to determine for some time now if its a Boss. Im not a fanatic about it just trying to now determine if my personal car is a Boss.

 

[mustang_paul]

Google the part number and see what comes up.

 

[fordguy]

those are factory boss 302 / 351 guide plates

 

[Maxum96]

those are factory boss 302 / 351 guide plates

Yup.

To the OP just to be clear, You have a mechanical cam in your engine. Those are factory Boss guide plates. But without knowing the casting numbers, those could be Boss 351 heads or 351C closed chamber heads converted to mechanical cam (very popular 351C modification). Your carburetor is not a Boss 351 carb. It appears your intake manifold is an aftermarket aluminum intake. Understand, a Boss 351C and a standard 351C with closed chamber heads will make exactly the same power if they're built identically. The Boss 351 specific parts just bring more money to those looking for them.

Where are you located?

 

[Klutch]

Just like the Boss 302, the Boss 351 is a very rare, desirable and expensive engine. That engine was available in the 1971 Boss 351 Mustang and nothing else. It was not available in any other car or truck. So, while it's technically possible someone put a real Boss 351 engine into your Mustang, it's extremely unlikely.

I have a 351 Cleveland in my 1970 Mustang. It has Australian Cleveland heads with Boss 302/Boss 351 valve guides. As Maxum96 pointed out above, this was a very popular modification.

As mentioned, the only way to tell if your engine is a real Boss 351 would be to check the casting numbers. Thus far, it's missing any parts which would suggest it's a real Boss 351. While your engine won't be as valuable as a real Boss 351, it could easily have just as much power; or even more. It's not difficult to build a 351 Cleveland to Boss 351 specs.

 

[Woodchuck]

Another way to find out the provenance of the engine would be to find the partial VIN on the back of the block see if it's on a registry somewhere or contact Marti Auto Works to see if you can buy a report. Yes, it will only have the year, assembly plant and sequential serial number, but if the assembly plant isn't an "F", "T" or "R" you'll know it wasn't put in a Mustang. You'll know the VIN will have to be 1F[or R or T] 02Rxxxxxx.

 

[DonJustham]

Yup.

To the OP just to be clear, You have a mechanical cam in your engine. Those are factory Boss guide plates. But without knowing the casting numbers, those could be Boss 351 heads or 351C closed chamber heads converted to mechanical cam (very popular 351C modification). Your carburetor is not a Boss 351 carb. It appears your intake manifold is an aftermarket aluminum intake. Understand, a Boss 351C and a standard 351C with closed chamber heads will make exactly the same power if they're built identically. The Boss 351 specific parts just bring more money to those looking for them.

Where are you located?

Yup.

To the OP just to be clear, You have a mechanical cam in your engine. Those are factory Boss guide plates. But without knowing the casting numbers, those could be Boss 351 heads or 351C closed chamber heads converted to mechanical cam (very popular 351C modification). Your carburetor is not a Boss 351 carb. It appears your intake manifold is an aftermarket aluminum intake. Understand, a Boss 351C and a standard 351C with closed chamber heads will make exactly the same power if they're built identically. The Boss 351 specific parts just bring more money to those looking for them.

Where are you located?

located near raleigh nc

 

[Maxum96]

located near raleigh nc

Was just curious about your car. I had a friend many years ago in S. California with a 71-73 (forget exactly which year it was) Sportsroof same color as your's with a 351C that was dressed up like your engine. Just wondering if it was possibly the same car. Probably not.

 

[DonJustham]

Yup.

To the OP just to be clear, You have a mechanical cam in your engine. Those are factory Boss guide plates. But without knowing the casting numbers, those could be Boss 351 heads or 351C closed chamber heads converted to mechanical cam (very popular 351C modification). Your carburetor is not a Boss 351 carb. It appears your intake manifold is an aftermarket aluminum intake. Understand, a Boss 351C and a standard 351C with closed chamber heads will make exactly the same power if they're built identically. The Boss 351 specific parts just bring more money to those looking for them.

Where are you located?

Hi would the standard 351c have the 2” harmonic balancer? The intake has D1ZX-9425 on it

 

[Maxum96]

Balancers can be swapped out. I'd have to see a picture of the balancer. Your intake does appear by casting number to be a Boss 351 intake. The chances of you having a legit Boss 351 engine are rising.

 

[DonJustham]

Was just curious about your car. I had a friend many years ago in S. California with a 71-73 (forget exactly which year it was) Sportsroof same color as your's with a 351C that was dressed up like your engine. Just wondering if it was possibly the same car. Probably not.

Well you know what? The car came from California and then the guy moved to NC. Still has California plates on it. I just looked at the old title and he lived in Alta Loma wherever that is in California? He seemed to think that it might be a Boss Engine but then on the otherhand he didnt verify it either.
I attached another picture

 

[DonJustham]

Well you know what? The car came from California and then the guy moved to NC. Still has California plates on it. I just looked at the old title and he lived in Alta Loma wherever that is in California? He seemed to think that it might be a Boss Engine but then on the otherhand he didnt verify it either.
I attached another picture View attachment 825934

Picture of balancer

 

[427heaven]

It seems to have a little of this and a little of that, starting at the top and working your way down... Carb nope, intake check- D1ZX very nice, heads appear to be 4. open chamber nope, guide plates check, distributor you need to open it up or give us some numbers pass, valve covers check, balancer check on size alone, if you pull the pan and see 4 bolt mains, and good guy rods your in like butter. Odds are you have the good stuff there . Congrats on what we see!

 

[Maxum96]

It seems to have a little of this and a little of that, starting at the top and working your way down... Carb nope, intake check- D1ZX very nice, heads appear to be 4. open chamber nope, guide plates check, distributor you need to open it up or give us some numbers pass, valve covers check, balancer check on size alone, if you pull the pan and see 4 bolt mains, and good guy rods your in like butter. Odds are you have the good stuff there . Congrats on what we see!

How can you tell they're open heads with them on the motor and not knowing the casting number? Otherwise I pretty agree with you on the rest.

 

[Maxum96]

Well you know what? The car came from California and then the guy moved to NC. Still has California plates on it. I just looked at the old title and he lived in Alta Loma wherever that is in California? He seemed to think that it might be a Boss Engine but then on the otherhand he didnt verify it either.
I attached another picture View attachment 825934

I don't think it's the same car unless a lot of things got changed. But over 30 years later, who knows. Alta Loma is near Pomona (LA area). I was further south in San Diego years ago. But cars move around.

 

[DonJustham]

I don't think it's the same car unless a lot of things got changed. But over 30 years later, who knows. Alta Loma is near Pomona (LA area). I was further south in San Diego years ago. But cars move around.

Sorry to be a pain but what should I check next? Casting number near the starter? Partial vin number somewhere on the motor block? Drop the oil pan?

 

[427heaven]

How can you tell they're open heads with them on the motor and not knowing the casting number? Otherwise I pretty agree with you on the rest.

The 4v open chamber heads have a 4 with a dot next to it or the 4. Closed chamber heads have just a 4 in the corner of the heads... the rest you need to look at the numbers for date codes etc.