I have a 360/c6 in my '74 F100 with the stock 2 barrel motorcraft carb but I want to put a new (better sounding) dual exhaust system in. Any ideas what size piping I should use? Should I invest in putting in headers? I want it bigger than stock to get rid of any unneccesary backpressure, but not to big that I loose the exhaust scavenging. Would it make any difference to the exhaust size when I put my K&N X-Stream air cleaner assembly? Any recomendations on mufflers? Flowmaster, Ect or glasspack?

 

backpressure is for sissies

Definately get headers, it's the best thing you can buy for a FE. I put a dual 2.5" exhaust on mine with 18" glasspacks and it sounds pretty good. I wouldn't go smaller than 2.5" though.

 

yes, like mentioned above definately get headers and get rid of those cheesy log manifolds. one of the better upgrades ive done. if you have the $$ get the headers ceramic coated (definately worth the money). ive got 2.5 on mine with flowmasters. sounds good. have fun.

 

Headers are a big plus. I have a 390 with headers and a three inch exhaust pipes on it and it runs and sounds great.

 

My '73 f100 2wd 390 has Dynomax ceramic coated headers ($225 in Jegs) and 2 1/4 duals with glass packs ($200 at local exhaust shop). It sounds great. With a stock 390, iron 4v intake with Edelbrock 600 carb and just a daily driver that rarely sees over 3500 rpm, I saw no need for more than 2 1/4 pipes.

Marty

 

I too am interested in different exhaust, but which Flowmasters are you guys using? I see Flowmaster mufflers being exclaimed to be great, but not which series.

 

My basic theory was to match the exhaust pipe diameter to the header collector diameter. Therefore, get a set of headers with the collector the same size as the pipe you want to run. I'd recommend 2.5".

Headers help these FE's a lot. They wont help as much as they could with the little Motorcraft 2 barrel on there, but they'll be there when you decide to step it up to a 4 barrel.

Mufflers:
Glasspacks sound nasty in my opinion. In a bad way. Some people like it though. It's got the whole "Look at me, I have the loudest truck around" appeal. Magnaflows (which I was talked into buying) are nothing more than glorified welded glasspacks in the shape of a muffler, filled with steel instead of glass. Still too loud for my taste. Flowmaster 40 series sounds kind of cheezy too, at least on the multitude of local Chevy trucks that have them. I'd look for something like a Flowmaster 50 or 70 series.

 

i run 1 3/4" headers with 2 1/2" pipe into the dynomax ovals, then 3" straight out the back.. sounds great and mellows right out at freeway speeds...

 

[QUOTE=boschman36].....I want it bigger than stock to get rid of any unneccesary backpressure, but not to big that I loose the exhaust scavenging..... [QUOTE]

What you are describing there is the basics of "Tuning" your exaust. The question is, what RPM do you want to tune it for? Do you want to be making the most posable power at 5000 RPM, or do you want the exaust to be most efficent at normal driving speeds? 1-7/8ths might be best for scavenging at 800 to 2000 RPM, but have too much backpressure at 5000+ rpm. On the other hand, 3-1/2 might be the best at 5000 rpm, but have next to no scavenging effect at lower rpms.

I've got a setup like yours, and I'm running 2 inch pipes and have no complaints. I rarely get my truck to 5000 rpm, and I can accelerate from 1500 rpm in 4th gear with 4000 pounds in the bed. YMMV.

As for headers, if you think you need them, you do. putting those on will make more diffrence than anything else you do to the exaust. I'm not runing them, I have enough problems scareing the GF when I hit the gas hard. if the truck had any more acceleration, she wouldn't ride in it.

 

I use it mostly for driving around town, occasionally for ripping it up to 60 real quick, but nothing long distance. Its primarily a work truck if that gives anyone a idea of what I should shoot for for the exhaust besides investign in headers.