13 replies to this topic

[Txquadhunter]

there are a few makers of headers for the 351m/400's. just most don't list them. as for bolt on kits ya maybe hard pressed to find any and i haven't ran across any. you'd probably get out cheaper by adding the headers you find and taking the truck to a muffler shop in your area to run your piping.

for $200 i had duel 2 1/2" pipe thru 2 40's flowmasters exit with 3 1/2" tips on my 79 bronco with the 351m it's got a good sound and power.

[Ziggy]

My current LMC catalog has a duel exhaust kit for 78-79 Broncos that will work with headers (so they say) for around 200 clams. You will need to buy the collectors tubes to make it all fit. You can get a free catalog through their web site: www.lmctruck.com

[highboy73]

if you have it exit in front of the rear tires i hope you like noise all the time,yes all the time.
if you have it welded up by someone have them put in a balance tube or x pipe,it's worth the extra money.
take your collectors up to the parts store and find an exhaust doughnut that fits inside but doesnt fall thru and use those instead of all the cheap gaskets they give you with the headers.you may have to do some looking but you'll find them

[Billz4x4z]

I know this is kinda late,but hey,i just joined.
I'm runnin Summit headers on both the trucks,they were a very easy install,and so far there the only header I have seen for that engine that you don't have to take them loose to drop the starter.as for exhaust system I got thr dual exhaust kit from JC Whitney a few years ago for the 1/2 ton,Had to make some minor correction to it cause it wasn't usin there headers.but it worked out great.Matter of fact the exhaust system is still holdin up rather well considering the enviroment its normally in.

Bill

[Billz4x4z]

The 1 on the 1/2 ton is the 1 the exits behind the wheels,with glas packs its loud but not to bad in the cab.
Now the 3/4 ton is different,I took the stacks off that it had when I bought it and brought em out just past the cab in front of the wheel,with the 40 series flowmasters its not bad at all ,It all depends on the muffler you use and how loud it gets in the cab.

Bill

[Billz4x4z]

As far as gas mileage you may gain some,the best thing you could do there is add a 4bbl intae and carb so it can breath even better.

Bill

[highboy73]

you can't just go and bolt on a set of headers the size of the primary tube and collector size and length affect hp's and tq
the size of pipe and length you run do you have a balance tube,do you want low mid or high rpm,do you have a performance cam?bolting on a 4bbl isn't the answer either,you could wash down the cyl. walls and burn the motor up.
THERE IS ALOT MORE TO BUILDING A MOTOR THAN A SUMMIT CATALOG.
if you want to start throwing stuff in you motor or on it that you know nothing about then go ahead,but if you want to build it then learn what you got and figure out what you want.

[Billz4x4z]

Like higboy says do your research...But adding a 4bbl and intake isn't gonna trash your motor.....Just gotta stick with a lower cfm carb so you don't get that washed down cyl wall effect,Knowing how to tune the carb in is a plus to...Must be doin somethin right,I took a wooped stock 351m that was gettin maybe 5mpg,and now gets close to 10 mpg.,and I got a much larger torque band,from 1500 to 4000 rpm to 1700 to 5000 rpm.Still wants to keep pullin at 5200 but I know someone would try to disagree. The Summit headers are 1 5/8" tube and they seemed to be pretty balanced,Having the exhaust done correctly to,Have a professional do it,need to keep all bends down to a minimum,and try to keep each side equal in length.H pipes have there up and down sides also