Changing firing order?

Topic: Changing firing order? (Read 1006 times) previous topic - next topic

Changing firing order?

September 02, 2005, 01:20:20 PM

I've gathered from looking around that the HO engine used a different firing order than my SO. I've also read I can acheive the same by switching up the spark plug wires and using a 351W cam. Since I'm hauling the engine apart right now anyway and replacing the cam among other things I'm in a position to do that but I'm wondering what the actual advantage would be?

Re: Changing firing order?

Reply #1 – September 02, 2005, 02:47:48 PM

The HO firing order allows you to use a higher lift cam. You will also need a mustang computer for the new firing order (need to send fuel to the appropriate cylinder as well as spark) as well as 19# injectors vs. 14# stock ones.

Re: Changing firing order?

Reply #2 – September 02, 2005, 03:04:53 PM

Quote from: SSX

The HO firing order allows you to use a higher lift cam. You will also need a mustang computer for the new firing order (need to send fuel to the appropriate cylinder as well as spark) as well as 19# injectors vs. 14# stock ones.

In an 83 the computer would be an issue? The injection is just a glorified carburetor, it doesn't care where the fuel goes.

Re: Changing firing order?

Reply #3 – September 02, 2005, 03:06:25 PM

Actually there is no computer, mine is a straight carbureted engine.

Re: Changing firing order?

Reply #4 – September 02, 2005, 03:40:33 PM

Whoops, didn't even think of the year, yeah no problem with a carb. Also, I can't remember how decent the '83 heads were, but you might consider swapping those while you are at it.

Re: Changing firing order?

Reply #5 – September 02, 2005, 04:34:01 PM

Yeah right now I'm concentrating on making the car run well. Down the road I plan to swap out the heads, manifold, headers, probably get a 4 BL carb on there. Plenty to do.

Re: Changing firing order?

Reply #6 – September 02, 2005, 10:15:20 PM

you should be able to snag some 87 up mustang E7 heads fer cheep as well as a stock gt cam. im not all that farmillar with the 83 blocks but i think they all used a 2 peice rear main seal. i think its also a flat tappet non roller engine so to use a roller cam it would need to be converted. maybe a truck cam would work as well, they werent roller untill something like 94. im still learning this myself but there are guys on this board that know their stuff....

Re: Changing firing order?

Reply #7 – September 02, 2005, 10:33:14 PM

Stick a Summit racing SUM-3601 in it, it will have a little rump in the idle and jou'll have good power from 2000-5500 rpm. Not sure which firing order it uses, doesn't really make that much difference(but IMHO the 351/HO order sounds stronger).