Hot Rods Flathead exhaust

Working on a new build, going to have a 276" flathead, L-100 cam, 4 bbl and center dump headers from Speedway. The headers have a 2 1/2" outlet which seems large for a flathead. Should I use their 2 1/2" pipe kit or reduce to 2" ? This will be more cruiser than hot rod, build thread to come soon for a Victoria length/style woody with '29 from the a pillar forward on an A frame.
Looking for info that will help me out.
Thank you,
RB35

 

2 inch exhaust is plenty for a 276 flathead.

 

A lot of folks like the sound of a flathead through two 1 3/4" straight pipes.

 

I have used those headers a couple times and they sell a 2.5 down to 2.0 reducer with a flange to match the header. I then used a really short 90 made from a 2 inch donut to head back.

 

I used 1.75" pipes on my flathead because that was the size of the 8BA connecting rods I used as pipe hangers.
Dance with brung ya.

 

Cast Iron Fentons, 1 3/4 pipe, no mufflers on my avatar. Sounds like a Chris Craft idling.

 

I worked for a Texas Harley Davidson dealership for 18 years. Back in the 90’s,2000’s and maybe later, an awful lot of Harley owners rid themselves of their stock exhaust —-meaning “donate” the old exhaust in favor of a whole new system. Most of the mufflers we are talking about came on Sportsters and medium size Harleys ——not on baggers and full dressers. They were bullet shaped, had the same size input and output and were chrome plated glass packs with a tack welded baffle inside. I would take a piece of pipe and a few sharp hits later,the baffle was removed. You could see from one end to the other(no obstruction) clearly and had perforated holes to “muffle” the sound. I have used them on three diff vehicles with gr8 results. Good sounding,chrome plated glass packs ,and all I had to do was fit them up. Had about a 1 7/8 diameter od on both ends and maybe 4 in diameter—-either end could be used for intake or exhaust—-they looked the same from both ends, and the best part they were always FREE!!!!

 

My current engine is considerably bigger at 321 ci. The lead pipes is 2 1/8 and the flange outlet is 4 1/2.
Don't skimp on size for exhaust pipe. With flatheads, bigger is ALWAYS better. I have used this same size header on 276 ci engines.
If you add a baffle as in the picture, it helps.

 

What are you doing on the HAMB when that buck is waiting for you for a fill up? LOL

 

This 1 had a killer 304 H&H built flatty in it, 2 1/4 straight pipes all the way out the back (no muffs)
Was quiet inside, but out back it would rattle the wax outta yer ears when ya got on it

 

Thanks a lot guys. I'm going to neck it down a bit and my friend gave me a set of Harley mufflers, so got to make them fit too.