Flathead Exhaust pipe question

Whats a good size width for an exhaust pipe from a '49 flathead back? 1.5"...2"...2.5"...3"...??? id like it loud deep and throaty

 

2 inch does a good job.

 

Back in the 60's I ran 2" back through 18" glass-packs on a '41 Merc with the pipes turned down just in front of the rear axle and it was definitely deep and throaty.

 

I built a 2" exhaust system for the '50 Merc in my '36 three window with Fenton headers. It was a lot of work to snake those 2" pipes trough the holes in the X-member, but it was worth it.

 

cool guys thanks, 2" it is!

 

Yep.....2"

Rat

 

The dual exhaust on my '50 is all 2" with 14" glasspack mufflers. Stock engine and cast iron manifolds. It sounds very quiet and 'burbles' a bit at idle, has a deep tone most of the time but really raps when revved out!! I love it. . . It crackles and pops on decelleration, which keeps pedestrian on their toes, (I like that too.) but you could fiddle with the idle mixture if the noise was too much.

 

I agree...2" will work just fine.

 

Run Straight open headers with two foot of pipe and attach one of these on the end. Every Flathead will sound good with these guaranteed.
http://www.speedwaymotors.com/SHORTY-MUFFLER,3568.html
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If you use 2" with long glasspacks don't be surprised if it's too quiet. When I started doing exhaust in the seventies the older guys used to bitch about it not having that old "flathead sound". They always blamed it on the "new glasspacks" I always used 2" pipe. The smallest that I stocked. I had a customer come in with a stock 51 Merc and insisted that I use 1 3/4" pipe. BINGO it had that old flathead sound from the 50s that was so hard to get. You may not want that classic sound like us old farts that remember what they really sounded like. From then on I ran 2" back to the shortest glasspack blanks that I could get and run 1 3/4" tailpipes out the back. Flatheads have a sound all their own when done this way. That mellow burble.

You cant make 239 CIs sound like a 427. I'd suggest you try running straight pipes with no mufflers. My 34 P/U has straight pipes and it sounds great. 1 3/4" tail pipes. (259 CI)

I ran straight pipes on a buddies 51 Merc and he loves it.

Leave a straight section where you can add glasspacks later if you want to later. I'm betting you won't want to change it a bit.

Years ago I bought the Smitty repos just to get that classic look on my 255 CI Merc powered sport coupe but I cut them off and replaced them with 12" blanks. It was a little better but still too quiet for my taste. I don't like raggedy noise from leaks, just sounds of a little HP out of the tail pipe.

Bigger pipe is not always better. That goes for the 3 fiddy-3 fiddy cookie cutters too.

 

awesome!! cant hurt to try it

 

never really thought about it that way....makes sense