So I Did Something Kinda Dumb...

[MikeGriese]

The engine from my '71 convertible is off getting dynoed this week. It's a 302 2v at the moment under a ram air hood (with a close ratio 4 speed toploader behind it), but the heads and short block are built for more. I figured I'd get the engine in the car and shake down a bunch of other stuff before going for more HP. Until tonight.

Ford had planned to offer a Boss 302 model in 1971, and actually had intake and exhaust manifolds cast with D1 part numbers. Of course Ford changed their minds, and the parts went into dealer/service stock. I ran across a Boss 4v intake (and valve covers!) with the appropriate part numbers and date codes that they could have gone on my car, given it's build date for what seems like reasonable numbers. I also found a drivers side Boss exhaust manifold. To complete the set, I need to find a passenger side exhaust manifold. If anyone has any leads, please let me know.

 

[detritusmaximus]

Are the Boss 302 exhaust manifolds different from Boss 351 manifolds?

 

[Sheriff41]

The driver side manifold is the hard one to find. It is notched to clear the oil filter. For the passenger side you could use a 351C 4V manifold.

 

[MikeGriese]

Are the Boss 302 exhaust manifolds different from Boss 351 manifolds?

Good question - I'll need to do some additional research. My gut says they are different.

 

[MikeGriese]

Good question - I'll need to do some additional research. My gut says they are different.

Later that day...

I misspoke - the exhaust manifold I have is D1ZE 9431-EA, which is driver's side. The intake is D1ZE 9424-EA. So I need the passenger side manifold.

From the mustangtek website (http://www.mustangtek.com/exhaust/Exhaust.html), the part numbers for 4v engines are:

Driver's side exhaust manifolds

C9OE-9431-B 69-70 351w Driver
C9OE-9430-B 69-70 351w Passenger

C9ZE-9431-A 69-70 Boss 302 Driver
C9ZE-9428-A 69-70 Boss 302 Passenger

D0AE-9431-B 70 351c 4v Driver
D0AE-9430-B 70 351c 4v Passenger

D0AE-9431-G 70 351c 4v 2" opening Driver
D0AE-9430-G 70 351c 4v Passenger

D0OE-9431-B 70 351w Driver

D0AE-9431-G 71 Boss 351 2" opening Driver

D1ZE-9431-BA 71 Boss 351 2.25" opening Driver

D1ZE-9431-BA 71-73 351c 4v 2" opening Driver


The key takeaway is that the prefixes and suffixes are matched for sets of exhaust manifolds. Kind of annoying when Ford used the same part number for manifolds that have different exit port diameters.

Oddly enough they don't have some passenger side part numbers for 71 cars. I can see doing new manifolds for '71 cars because of the different engine bay dimensions. The drivers side is more restricted, whereas the passenger side would have more space available than earlier cars. At this point in the research, I suppose Ford could have continued with the '70 vintage passenger side manifolds as they probably fit the engine compartment. More research required.

 

[detritusmaximus]

If the regular 302 drivers side manifold did not change from 70 to 71, then there's a chance the 69-70 Boss manifold would fit. If that's the case, the H pipe might work as well.

 

[Hemikiller]

351C driver's manifolds were changed for the 71 Mustang/Cougar due to the relocated clutch linkage pivot. Torino/Montego also used it 72~74. Passenger manifold is the same 70~74 for all applications.

Casting number is simply the raw part, and it can be used for multiple applications with different machining. Best examples are the D0AE-L and D2AE-CA blocks, which were machined for both 2 and 4 bolt mains. The Boss 351 manifolds are likely just a cost cutting measure.

The Ford MPC shows the same part numbers for 69~71 for the Boss 302 exhaust manifolds.

 

[MikeGriese]

Thanks - that helps!