Fox T-Bird/Cougar Forums

Technical => Engine Tech => Topic started by: sum_weirdo on September 02, 2005, 01:20:20 PM

Title: Changing firing order?
Post by: sum_weirdo on 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?
Title: Re: Changing firing order?
Post by: SSX on 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.
Title: Re: Changing firing order?
Post by: amooset on 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.
Title: Re: Changing firing order?
Post by: sum_weirdo on September 02, 2005, 03:06:25 PM
Actually there is no computer, mine is a straight carbureted engine.
Title: Re: Changing firing order?
Post by: SSX on 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.
Title: Re: Changing firing order?
Post by: sum_weirdo on 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.
Title: Re: Changing firing order?
Post by: shame302 on 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....
Title: Re: Changing firing order?
Post by: TurboCoupe50 on 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).