Thread: How to tell what firing order

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Howdy Gang,
Is there a easy way to tell what engine we have? It is in a sports fishing boat Mercruiser 215- small block Ford 6 bolts on valve cover
I was told 351 cu in but it seems more like a 302.After a couple of wrong gaskets sets the one that fits said 302 on the package.
it took 4 different tries to get a new oil pump that fit.
I see in my motors manual that the 302 and 351 have different firing order
both rotate the same direction likewise the distributors.
any way to tell which timing order to go with?
thanks
hank

Did you check if it's cast in the intake manifold??? Behind the carb..

daffy427- no but I will now
thanks
and just what is the thing in your avatar
looks pretty cool
hank

after I lifted the PVC hose
All I can see are the words firing order
darn they must have written the order in pencil
still searching for the answer

hank

They might have ground it off because it might be a 302 with a 351 camshaft.. If that's the case it would use 351 WINDSOR firing order..

302/351/5.0/5.8 -

Now that you are confused, let me just add one more thud to your day - it could just be a reverse rotation motor These are often used in boats.

221 - 302 = 1-5-4-2-6-3-7-8
351W(all) & 5.0 H.O. and late 5.0 non H.O. = 1-3-7-2-6-5-4-8

Here's the info for a marine engine: http://www.basicpower.com/firingorder.htm
If memory serves me correctly, but not positive, these reverse rotation engines may be cylinder numbered from the transmission end!!!

Then to make life even more fun, RR motors have different camshafts, distributor drives and water pumps. Other then that - about identical to standard rotation

Having fun yet!!!

Most single engine configuration boats are standard rotation..If that makes you feel better..

Pull the valve cover and turn it until #1 intake opens. Keep turning and watch which one opens next. If it's #5, then it's 15486372. If it's #3, it's the other one.

Thanks guys
I'll pull #1 valve cover and hope #3 moves to tdc when I spin the crank
(if I'm going in the right direction)
I didn't notice which way the starter turns before I tore it out.

I just reinstalled the motor into the boat after re-ring/new bearings -oil pump-valve job

heading back out to the shop for some more fun


from google
When swapping parts between these engines, the most confusion surrounds the camshafts. Camshafts will interchange, but the 351W has a different firing order (1-3-7-2-6-5-4-8) compared to the 289/302 (1-5-4-2-6-3-7-8). Compounding the situation, the '82-and-later 302 HO engines use the 351W firing order.

the 215 Mercruiser is a 302. think the 225 and up is a 351..

I always wondered why Ford had so many firing orders when the rest of the world uses 18436572... I have no idea how many V8 firing orders they have..I do know there was one year that the 4.6 had 3 of it's own..

There are lots of V8 firing orders. Buick used 12784563 for years!

Ford is the one that has the firing order Right , It starts with 1 and ends with 8 . Some GM tech guys are also finding an advantage in changing the order from firing to exhausting . GM techs found this out in 2004 the ford guys spotted this advantage during Trans am racing back in 1968. If your not sure of the order find the number one spark plug wire on the distributor cap , follow the plug wire next to number one if it's
"3" you have the Marine or Windsor order . If it's number "5" you have the street or 302 order . If it's number "8" you are going the wrong way . Marine 302's had the 351 firing order before the 302 ho used it , For the first 302 ho Ford used a marine cam.

Originally Posted by R Pope

Pull the valve cover and turn it until #1 intake opens. Keep turning and watch which one opens next. If it's #5, then it's 15486372. If it's #3, it's the other one.

That's a great tip Ron. Logical, but unless you stop to think about it this would never dawn on you. I've filed that one away.

Don

The other odd thing about ford was their numbering on the cylinders with 1234 up one side and 5678 up the other bank rather than even and odd like everyone else..Are the newer V8 Fords like that too??