Distributor

[RacerJames]

Firing order has nothing to do with the mechanical operation of the dist. Yes the firing order changed on all 5.0 engines made after '86. The firing order on all Ford small block engines (5.0 and 5.8) from '86 to the end of production was the same. Firing order is determined by the cam. in '86 and later it is 1-3-7-2-6-5-4-8.

 

[RacerJames]

If I recall right, a 351w gear outside is the same as a 302, but the shaft drive is different on the bottom ( and maybe the length????) I never thought about a 351c or m being able to swap or not.

Yes, you recall right. The 260/289/302 used a 1/4 inch oil pump drive rod. The 351 W, C, M, 400, and 429/460 all used a 5/16 oil pump drive rod. The Dist. length was the same for all of these engines, and the only difference between them was the drive rod diameter and the gear. I know this because of the aforementioned experiences with the stock car.

 

[7991LXnSHO]

With the firing order switch from the standard to the later HO order, I used a flat tappet 351W cam in my 79 302 block. It was the right size camshaft for cheap or I would not have done it.

 

[RacerJames]

I recommend using the 351W cam in any flat tappet build. It's my understanding that all roller cams from Ford are the "HO" firing order, thus, it's a no brainer to keep roller motors that way. The engineering behind it was for the 351W, (new for '69) because they wanted to unload the #1 crank journal. Turns out, it's more efficient to fire all small blocks that way. It only took 15 years for the ponderous entity that is Ford Motor Company to go all in with a better design.

 

[7991LXnSHO]

Chevy cams can be ordered with a similar cam order swap for that reason. But as they do not put cylinder # one in the right spot, who knows if it counts.

 

[RacerJames]

There are three kinds of people, those who can count, and those who can't!

 

[65ShelbyClone]

Lets clear up a few things:

1.) Flatt tappet cam = iron distributor gear.
2.) Roller cam = steel distributor gear.
3.) Gear pitch is the same.
4.) 351W distributors are taller than 302 distributors because the 351W deck is taller.
5.) "HO" 5.0 firing order is borrowed from the 351W that preceded it.
6.) Smallblock Chevies have the same firing order as the early 289/302 when using Ford cylinder numbering.
7.) LS-series GM V8s have the same firing order as the 351W/5.0HO when using Ford cylinder numbering.

The story I have always heard about why the firing order changed was to prevent crossfiring between cylinders seven and eight. True or not, I don't know. Doesn't really matter.

 

[RacerJames]

Everything you said is correct, except:

4.) 351W distributors are taller than 302 distributors because the 351W deck is taller

The deck is taller, but the dist. mounting point is the same. Notice the tall rail behind the dist. on a 351 that isn't there on a 302.
The cool part is, one can put an oil pump and dist. From a 351 into a 302 and gain the added strength of the 5/16 drive rod.