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1969 Mustang Mach 1, M Code is it a windsor or not?

34K views 26 replies 8 participants last post by  rodbender 
#1 ·
I have been confused for the past 3 weeks trying to find an answer. I know why the engines are called Cleveland and Windsor. But i have been trying to find a long block 351W M code. Thats a 290 Hp engine. No matter where i go they tell me an M Code is a Cleveland. Some one please point me in the right direction. My current engine is a 351 Modified 1973 F series truck engine. Long story. I pulled this Mach 1 out of a corn field in Nebraska. Really i did.
 
#2 ·
"Correct" motor



If you are looking to restore the car to the "correct" motor, the M code 290 hp 351 (assuming it had an "M" code in the VIN) would be correct.

In 1969, I believe that motor WOULD have been made at the Windsor plant (which was just closed down, by the way).

Now, I'm not sure whether in other model years the Windsor plant made a 290hp rated 351 or not - I'll dig around and see. But you should be able to find a 290hp 351 Windsor motor.

Here is the method for identifying the 2 and some data about their differences (which you say you know about, but hey, maybe this will help):

Now a 351 Windsor is really a slightly enlarged 289/302, as it's name implies it comes from Fords "Windsor" engine family (a.k.a. the 90-degree V engine family). The thin-wall cast SMALL BLOCK accepts regular sized spark plugs, uses a timing chain in the block, routes water through the intake manifold, features thin main-bearing caps, a very good oiling system, and uses the same heads for 2V & 4V versions. The heads are are small, utilizing in-line valves with relatively small ports. The valves are 1.78" intake and 1.54" exhaust, i.e. the same size as a 289/302. The valve covers are straight (front to rear), attached by 5 bolts, and when removed you can see 351 cast in the lifter valley. The small side-by side (in-line) valves are the dead give-away.

The 351 Cleveland, on the other hand, belongs to Ford's 335 engine family. This thin-wall cast BIG SMALL BLOCK uses the smaller 14mm spark plugs, has a separate front cover (bolted to the block) housing the timing chain and routing water - so that water does not go through the intake manifold, features beefy main caps (wide enough to drill for 4-bolt mains), a poor oiling system, and uses different heads for 2V & 4V versions. The heads make all the difference and these fire breathing babies make this motor the legend it is. On the 4V, the valves are HUGE, measuring 2.19" intake and 1.7n" exhaust (don't remember exactly). Valves this large are only possible via a canted valve arrangement, forming what Ford refers to as a "poly-angle" combustion chamber. The valve covers are not straight - the front is flat and parallel to the ground, but a curve twists the rear parallel to the head. They are attached by 8-bolts and when removed, there is a 4 cast into the corner of the 4V and a 2 cast into the corner of the 2V (at least in 1970). The canted valves are the dead giveaway.
Summary of Quick ID351 Windsor 351 Cleveland 5-bolt straight valve covers 8 bolt 2-plane valve covers radiator hose to the intake manifold radiator hose does not connect to intake regular 5/8" spark plugs small 14mm spark plugs
 
#3 ·
Hello.:) 351 Clevelands weren't available until the 1970 model year. Your car came with a Windsor. The M code in 69 is, in fact, a 351 Windsor, but for a 70 mustang, an M code means a 351 Cleveland. It's an F code on a mustang with a 65 vin is a 260 2bbl but from 68 on an F code is a 302 2bbl. Hope that helps.:)
 
#7 ·
Aftermarket

Because the Cleveland made better power, all the focus in the aftermarket (and all the demand in the form of orders going to Ford after the 351 run) were Clevelands.

This usually happens in the aftermarket - rather than stock 2 similar engines that, however, have virtualy NOTHING in the block that interchanges, they pick the one that sells best and focus on that. The same thing has happened repeatedly.

Old blocks that will do the deed are, however, not uncommon. They just aren't part of the mass aftermarket cycle per se.
 
#9 ·
351 W



"Now a 351 Windsor is really a slightly enlarged 289/302, as it's name implies it comes from Fords "Windsor" engine family (a.k.a. the 90-degree V engine family). The thin-wall cast SMALL BLOCK accepts regular sized spark plugs, uses a timing chain in the block, routes water through the intake manifold, features thin main-bearing caps, a very good oiling system, and uses the same heads for 2V & 4V versions. The heads are are small, utilizing in-line valves with relatively small ports. The valves are 1.78" intake and 1.54" exhaust, i.e. the same size as a 289/302. The valve covers are straight (front to rear), attached by 5 bolts, and when removed you can see 351 cast in the lifter valley. The small side-by side (in-line) valves are the dead give-away".

If its a bare block, look for the "351" cast (NOT stamped) in the lifter valley.

If its a complete motor, note the other features described above. The valves being "in-line" (not staggered or canted) is the quick giveaway sign.
 
#11 ·
Ms V, are there some easy to spot stamped data on the 351 blocks to decode?
Hi again.:) Yup. The casting number on the p/s of the block will tell you exactly what it is. You have to move the starter to see it. It should be C9OE-6015-B, followed by a single digit number which will tell you the application. There should also be a partial vin stamped on the top of the block all the way in the back, behind the back of the intake manifold. If it left Ford with a car wrapped around it, that is. A windsor will have the upper radiator hose going into the front of the intake, just like a 289/302. A cleveland will have it going straight down into the top of the front of the block itself. If he pulls a valve cover off, it say '351' on the top of the head. The windsors have six valve cover bolts instead of 5 like a cleveland. If he has a 69 model car and it has the partial vin of his car stamped on the back of the block, it's a windsor and there is all sorts of information available about the specs and output of his car.
Andrew, there were no 69 model cars that left the factory with a 351 cleveland. Not one. Even the 70 Shelby GT-350s had windsors, because they were re-titled 69 model cars. People do all sorts of funny things to cars, and 35 or 40 years is a long time. If it's a 69 model car that came with a 351, then it came from the factory with a windsor. For sure. The cleveland did not exist in 69. That would be like a 67 model car with a 302 in it. It didn't happen.:)
 
#13 ·
Veronica's right, there was NO 351 Cleveland option for the 1969 model year. There was 2 351W's, a 2 barrel 250hp version, engine code H, and the 290hp with the M code.
 
#14 ·
Bolted

Veronica's right, there was NO 351 Cleveland option for the 1969 model year. There was 2 351W's, a 2 barrel 250hp version, engine code H, and the 290hp with the M code.
OK, but how many valve cover bolts did the W have?

I say 5.

She say 6.

Hmmmm. Starting to sound like some Barrett-Jackson rap song!
 
#15 ·
Hi again.:) I recently took an online test about gender-related stuff. The results said that I was 86% feminine and 14% masculine. I thought that this sounded odd so I looked a little closer and it seems that I would be the perfect woman,according to the man that designed the test, if I was significantly dumber.:gringreen It's 6 valve cover bolts, 3XBlack.:) They're just like a 289/302 valve cover, while the Clevelands are more like a Boss 302.:)
 
#17 ·
Hi again.:) On re-reading that last post of mine, I can see how it would be very easy to take that the wrong way. Please don't:) I just thought that it was strange that reasoning skills got thrown in as a gender issue in that test, and now that, apparantly, I am officially an 'honorary guy', from the neck up, anyway,:gringreen, it's ok for me to go ahead and be right every now and then. That's all I meant.:)
 
#20 ·
The engine

Yea the post you sent was the engine i was wanting to buy. But im in Manhattan Kansas. He is not a dealer so i would either have to drive to Maryland and pick it up or ship it at 2 dollars a pound. Its a 530 pound engine. SO im stuck piecing one together. I have found what i believe to be a 69 block and somewhere else 1969 4V heads. but how do you ID the year the block was built?
 
#22 ·
Vin

Yea the post you sent was the engine i was wanting to buy. But im in Manhattan Kansas. He is not a dealer so i would either have to drive to Maryland and pick it up or ship it at 2 dollars a pound. Its a 530 pound engine. SO im stuck piecing one together. I have found what i believe to be a 69 block and somewhere else 1969 4V heads. but how do you ID the year the block was built?
There should be a partial VIN on the back of the block (if, as Ms. V said, it was shipped from the factory with a car around it). There is a site...

That just slipped my mind where you can decode a VIN.

I'll see if I can locate it and post it here. Back soon...

69 Mustang VIN decoder

The Engine code will be bracketed by numbers (the body style number to the left, the unique build number of the car to the right). The letter in between will refer to the engine type.

The entire VIN will tell you the model year, with the first number being the year (9 = 1969).

[quote Ms. V] The casting number on the p/s of the block will tell you exactly what it is. You have to move the starter to see it. It should be C9OE-6015-B, followed by a single digit number which will tell you the application.
 
#24 ·
Hi again.:) You guy are so sweet.:embarrassed If you get the chance to actually look at the block yourself, there is also a date code next to the casting number that is covered by the starter which will be in the format of Y/M/D. For example it might say 9L27, which would be Nov.27 1969. Also, if it has no oil pan on it there will be an assembly date stamped on the block back near the rear main cap if it left the factory as an assembled motor rather than just a bare block. Good luck.:)
 
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