351W with a 302 cam

[tcrist]

Is it normal for an engine shop to put a 302 cam in a 351W?

I know I have a 351W in my CR. Looking up the cam, it is a (Comp Cams P/N 31-242-3) ( grind FS XE268H-10).

The reason is that I am getting my engine back together (had to have head work done) and trying to get everything set and looked up the firing order in a manual and noticed that the firing order was incorrect for a 351. It is correct for a 255,302,429 & 460 but is incorrect for a 351 & 400.

I never pulled the plug wires off of the Dizzy cap so I am sure of the firing order and my cam sheet states the firing order is 15426378.

It was running fine before, other than pushing water out the overflow at a high rate.

I guess as long as it goes together and runs, what the heck.

[brandx]

designation of 302 or 351 does not matter. Just make sure you have the right timing order that is for the cam

[tcrist]

Thanks,
It just does not make any sense to me. I know that it works because it ran fine but its wierd. If I had of removed all of the plug wires from the cap and then tried to put everything back together buy the book, I would have been lost. At least I would have had the cam paperwork to go buy that states the firing order on it.

Now just wondering what other wierd crap the engine builder did.

[olddog]

From what I have read, Ford changed the firing order on the 351 to lessen loading on the main bearings. Some 302/5.0 engines used the 351 firing order while others stayed with the old firing order in the same year. It seems like the later 5.0 all used the 351 firing order, but I don't trust that memory.

I've heard claims of Hp differences, but never a controller dyno test to prove it. Love to see one though.

If you are running multi point EFI it matters, otherwise I doubt it.

[DAVID GAGNARD]

Camshafts for a 302 or 351-W are interchangeable,the camshaft will determine the firing order, that's all you have to worry about........
Some prefer the old firing order, while some prefer the new one.........

David

[tcrist]

olddog,
I am running a carb so no EFI to worry about.
I can scan my dyno sheet and send it to you if you want.
Some having it one way while some have it another for the same CI and same year is really confusing.

David,
Just another thing to have to remember I guess. As long as it runs good, that's all that really matters.

One question though, why would they have two different firing orders on a V8? Being that my book shows one for the 351 & 400 but different for the rest.

[DAVID GAGNARD]

David,
Just another thing to have to remember I guess. As long as it runs good, that's all that really matters.

One question though, why would they have two different firing orders on a V8? Being that my book shows one for the 351 & 400 but different for the rest.[/quote]

I'm guessing enginering and technology played the part in changing the firing order...also maybe the advent if EFI.....
Personally,I don't see much if any difference in the two, what I look for is a camshaft that has the lift/duration I want and I use that one,regardless of which engine it was designed for..........just be sure to use the firing order for that partciular camshaft.....

David

[bill37341]

A few years ago Hot Rod ran an article about changing the firing order of a chevrolet to that of the 351 Ford . They also ran dyno tests on it. If memory serves me correctly, the motor made measurably more power. I'm not sure why your builder chose the 302 cam, but it really only matters what is on the cam card. Could be the best cam for your weight, driving habits etc. (Could be that is what he had on the shelf.) Since the 351 was developed 7 years after the 221 small block, it could be that Ford made the change to give a little more power. A running change to the 302 would have been confusing to some, so they left it the same as before. Regardless, you are fine with the cam. Bill.

[tcrist]

Gotcha, thanks guys.

One other question though, what about the crank? Would there be a different crank if they are running a 302 cam? Might be a dumb question but I do not know a dam thing about this.

[DAVID GAGNARD]

Originally Posted by tcrist

Gotcha, thanks guys.

One other question though, what about the crank? Would there be a different crank if they are running a 302 cam? Might be a dumb question but I do not know a dam thing about this.

NO,Crankshaft has no bearing on camshaft,2 indepedent parts......

302 and 351-W cranks are two different animals,both in stroke and main/rod bearing size.....

David

[tcrist]

I understand that the cam and crank are seperate items but they are timed with each other. So I guess that means the rod journals on the crank are in the same spot on a 302 & 351. Be it 180° apart or what ever. So that means that TDC on all pistons for the 302 or the 351 reach their limits at the same time? I.E. the angle between the 1-5 rod journal and the 2-6 are the same on the 302 & the 351?

Ok, I am starting to confuse myself by my rambling.

[Barnsnake]

Remember it's a 4-cycle engine. The piston comes to the top of the stroke twice for each power cycle. Whether a given TDC is the compression stroke or the exhaust stroke is controlled by the cam. That's how you can have multiple firing orders with the same crankshaft.

[DAVID GAGNARD]

Originally Posted by tcrist

I understand that the cam and crank are seperate items but they are timed with each other. So I guess that means the rod journals on the crank are in the same spot on a 302 & 351. Be it 180° apart or what ever. So that means that TDC on all pistons for the 302 or the 351 reach their limits at the same time? I.E. the angle between the 1-5 rod journal and the 2-6 are the same on the 302 & the 351?

Ok, I am starting to confuse myself by my rambling.

I see what your getting at, and while I'm no engineer,the 351 came a few years after the 302 and was based on the 302,smae bore,just longer stroke,so they engineered the 351 based on the 302,that's why the camshafts are interchangeable........

I don't put much thought into it, the Ford engineers did that already......all I know it works....

David

[olddog]

The 15426378 firing order was used by the FE, and 385 series engines, in addition to the SB Ford. The 351 W and 351 C (and 400) used the 13726548 firing order.

If you sit down and draw out the firing order and then re-number the cylinders as Chevy and Mopar numbered them, you will discover that they also used the 15426378 firing order. The difference is that they numbered the cylinders differently.

I saw the show Bill37341 mentioned on the SB Chevy. I didn't catch the firing order and was not able to confirm it was the same as the 351 Ford. I was thinking they only swapped 2 cylinders and the 351 swaps 4. I wish I could find this out for certain. They did prove the other firing order made more Hp. Memory is somewhere between 5 and 30, but I'm thinking around 10 hp. They said it was do to air flow improvement in the intake manifold, by changing the order the flow hops from port to port. It would also change flow pulses in the exhaust.

[wolf k]

I read somewhere that the order change was to relieve load off the no 1 main bearing because of all the auxiliaries that were being added to the front of the engines at the time.

[tcrist]

Thanks guys,

Like it was said, as long as it runs right it is ok. Just another item to write in the book for when I sell it (or give it to my youngest). Don't want somebody else to have to go through this.