Mystery Engine In My 65 Stang


New Member
Jun 26, 2004
Hello, this is my question here!

I bought a 65 Mustang a couple of weeks ago from a dealer. The does not know the history of this vehicle. As far as I know, VIN shows that it came with a 289 with 2bbl. The intake manifold has 289 stamped on it. When I took the valve covers off to replace them, I noticed that the heads have 302 stamped on it. Does that mean that the engine has been swapped out with a 302?

Another mystery is regarding the firing order. I replaced the distributor with an electronic type. According to the Chilton manual, all V8s except for 351 has the firing order of 1-5-4-2-6-3-7-8. I placed the wires according to that order and fired it up. It was running quite rough, so I shut the engine off, and by feeling the headers, I noticed that only 4 cylinders where firing. The cylinders that were firing were 1,2,6, and 8, which just happen to be same for the 351 firing order of 1-3-7-2-6-5-4-8. So I went ahead and rearranged the firing order to match the latter one. It now fires up and runs like a champ.

I’m 99.99% certain that the engine I have isn’t a 351 since it a manifold for 289 couldn’t be used on it. Do any of you know that’s the deal with the firing order, or maybe the Chilton manual is wrong here?
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Most likely you have a 289 with 302 heads. Not un-common.

I can't begin to help you with the firing order. Obviously the car is no longer stock but i am pretty sure that is a 289 with 302 heads. But if I am wrong, someone will come along and help you out.

Just my thoughts
Firing order is determined by the cam, and they are interchangable between the 289/302 and the 351.

The car is 40 years old, it could have either a 289 or a 302 in it. No telling without checking the stamping number. I believe it is down by the skirt of the block by the starter.
That's for the quick replies.

Max Power: Isn't the firing order determind by both crank AND cam, firing at TDC with both valves closed?

65straightsick: Is there a reason why someone would put a 302 head on at 289? I figured the previous owner replaced a tired 289 with a 302 because 302 was more common.
don't get too worked up about it, virtually no difference between a 289 and 302. They're both good engines, the block/heads/manifolds/pistons all interchange. The 289 uses a slightly longer rod and a crank with slightly less stoke. Only way to really tell for sure is to get the castings numbers off the crank or the rods. Even if its a 289 block, it could have 302 internals. But what does it really matter. It obviously has a 351 firing order which is determined by the camshaft. 289's and early 302 used one firing order while later model and high output 302's used the 351 firing order which is generally regarded as being slightly better.
Thanks for the info, 302 coupe. At this point, I'm assume that the previous owner swapped the engine out with a later model 302. And that may be a good thing because the dealer sold it cheap because the engine ran rough and I checked the old wires before pulling them off and they were set to the old 289/302 firing order.
The only thing any of us can tell you is that the heads are 302. Give us the coding on the block and you will have your solid answer.

There are slight advantages with the 302 head. But not much. And the only true difference in the two engines is about 13 inches displacement. So the 302 is a little more powerful if i'm not mistaken. Good luck with your build up. Let us know what you find out.
I tried to get the casting number, but it came with a set of headers and it seems impossible to get the numbers without having to take it off.

At this point, I believe that 302 coupe's reply makes sense because I don't see why the previous owner would swap the cam out but keep the original intake and carb. My guess is that he yanked the tired 289 out and just dropped in a more common 302 at that time.
Id try the 351 and 5.0HO firing order, and if it runs great you know. also check casting numbers on everything:timing cover, water pump, anything that is ford. Also dont the early 289s have one less bellhousing bolt than newer ones? It also may be interested if you find an 1980s or 90s casting number on the block to pull intake to see if its a roller block
good point sg465. If its a roller block you'd be a step ahead. Besides the roller cam, HO motors will have a 1 piece rear main seal and a 1 piece rubber oil pan gasket. If its a roller block, it should have some sort of plug(cork, wood, rubber) in the side of the block on the drivers side to fill in the hole left by the factory dipstick. If you start checking casting numbers on the cranks, a pre 82 casting will have a '2M' cast into it, while 82 and up will have '2ME' cast into them(I think...). They switched to roller cams in the HO motors in 85 or 86. Only early 289's have 5 bolt bellhousings, usually just left over 64 castings. Chances are its the 6 bolt variety. It sure sounds like a salvage 302 with some of original 289's accesories bolted to it. Chasing part numbers on external engine parts could really get confusing if thats the case. As long as it all works together and runs good, you should be set.
If it is a late model 302, it'd have a roller block, it could be an early block with a roller conversion, or a early 302 with a 351w cam in it, it could even be a 289 with later 302 heads and a 351w cam. The early timing cover has the dipstick in it whereas the late model had the dipstick go in the side of the pan. The early cover has a provision for a manual fuel pump and will only use a early style regular rotation water pump. I believe the late model cover has no provision for a manual fuel pump and only uses a reverse rotation water pump. Either cover can be put on a late or early model block. The starter could be an indicator as well but either can go here as well, the block casting number is under the starter BTW. Removing the intake will tell you if you have a roller block or not and if not, if a roller cam conversion is installed.

It sounds as though you have sort of a bastard motor there, but it's not all that bad, it'll work.
Yep, everyones right. Ive been in the "bastard motor" scenario before, even put together a few. 1320stang is right with all the different combos. I would definitly try to determine if its a roller block(ecspecially before you replace distributor!!) its just real nice to know what you have so when the guy running the computer at the parts store tries to figure out what part he thinks you need. one thing for sure, not short on experience here! What size socket does it take to get spark plugs out?
""Max Power: Isn't the firing order determind by both crank AND cam, firing at TDC with both valves closed?""

Wellllll, technically yes. But for your application, different firing orders are achieved by a simple cam swap........
One way to tell if you have a 289 or 302ho without pulling intake off is byt looking at the crank bolts on harmonic balancer the 289 has 3 bolts the 302 has 4. this will get you that much further. I would bet its a 289 early 302 with 302 heads and 351 w cam. Let us know. Reason being anyone who would go through the trouble of putting a 5.0 in a old stang would know the diff in the firing order. I would think anyway.
Maxpower: I guess you may be right since the piston would be at DTC on both compression and exhaust stroke and a cam change can reverse them.

1320stang: I did swap the intake out and it does not look like it has a roller cam setup. I do believe that late model 5.0's do not have a provision for a manual fuel pump and this motor does have one. Dipstick is also up front as well.

Thanks for your inputs, everyone! I will start searching for casting numbers over the weekend. I'm not planning for an original restro, so having a bastard engine doesn't bother me much since it seems to be running fine.