56 FLH - Stay With "True" Dual or Convert to 2 Into 1?

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DaveSwanson
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56 FLH - Stay With "True" Dual or Convert to 2 Into 1?

#1

Post by DaveSwanson » Wed Feb 18, 2009 1:35 pm

My 56 FLH's original rear header is shot and needs replacement. Therefore I have the opportunity to buy a replacement rear header and keep it as a dual exhaust or buy the parts necessary to convert it to the factory 2 into 1 style.

I imagine that the 2 into 1 makes a bit more power than the old true dual with no crossover. No crossover and that severe bend right out of the exhaust port can't do much for gas flow and looks like it would always be a problem with stress fractures. It just looks to me that the 2 into 1 would be a more optimized system and the exhaust gases from the rear certainly have a less torturous path. And i think the 2 into 1 looks better too.

Does a 2 into 1 make more power than the old true dual?



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Re: 56 FLH - Stay With "True" Dual or Convert to 2 Into 1?

#2

Post by john HD » Thu Feb 19, 2009 2:19 am

dave

i have not had the chance to ride a true dual bike. i can not offer a "seat of the pants" opinion.

however i imagine the shorter single style muffler would have less restriction.

then again, a set of staggered duals would optimize flow. i'm gonna just venture a guess and say you are not headed in that direction!

john

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Re: 56 FLH - Stay With "True" Dual or Convert to 2 Into 1?

#3

Post by Cotten » Thu Feb 19, 2009 2:49 am

The charm of a true dual exhaust note puts all others to shame.

I regret that only two of my machines are outfitted in that manner.

Beware of Paughcos that are bent in the '65 and later fashion.

....Cotten
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Re: 56 FLH - Stay With "True" Dual or Convert to 2 Into 1?

#4

Post by DaveSwanson » Thu Feb 19, 2009 3:23 am

Cotten wrote:The charm of a true dual exhaust note puts all others to shame .....Cotten
That's enough of an endorsement for me! Dual exhaust it is then.

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Re: 56 FLH - Stay With "True" Dual or Convert to 2 Into 1?

#5

Post by FlatHeadSix » Thu Feb 19, 2009 4:01 am

and they look as good as they sound, dual=cool!

I was going to put my vote in earlier for the duals, but I read your first post the same way John did, it sounded like you already had your mind set on the single exhaust.

If I ever have to replace the exhaust system on my '49 it will get the true dual treatment.

I have always wondered about the affect of the contorted bend on the rear pipe but after giving it some thought I don't guess its any worse than the "squish" on the front pipe, they probably balance each other out.

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Re: 56 FLH - Stay With "True" Dual or Convert to 2 Into 1?

#6

Post by Kuda » Thu Feb 19, 2009 1:32 pm

DaveSwanson wrote:No crossover and that severe bend right out of the exhaust port can't do much for gas flow and looks like it would always be a problem with stress fractures.
I've always run true duals, but I'm also an old hot-rodder so it's kinda in my blood. That said, I don't think you'll see a performance difference between 2-1 and 2-2 pipes on these old pans, unless you're running a hot motor with lots of cam overlap. If you really care about performance, there are a couple of things to keep in mind: 1) size of the pipes. Again, assuming a stock motor, running 2" pipes will kill a fair bit of low end power and can make tuning a PITA. 2) Mufflers are more important than pipes. On a stock street bike, a large chamber low restriction muffler will always outperform straight pipes and small corked up mufflers. That said, a set of fishtails or small baffles in 1 1/2 - 1 3/4" straight pipes will run surprisingly well. Loud, but run well. 3) If you do decide to go true duals, make sure you get and use the rear pipe bracket that bolts to the right rear cylinder base bolt. Without that, you're putting a lot of stress on the rear exhaust port, asking for leaks, and possibly stress fractures in the pipe. It's a pain to get on there, but it works well. And finally, 4) whatever pipes you run, unless you're running a raked out long bike with tons of clearance, always use the stock (or something like it) squish pipe on the front. Otherwise you're losing a lot of ground clearance that you really might need at one point...usually very suddenly. :shock:

-Kuda (oh, and Cotton's dead on there, too) :mrgreen:
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Re: 56 FLH - Stay With "True" Dual or Convert to 2 Into 1?

#7

Post by Cotten » Thu Feb 19, 2009 4:30 pm

There's just something about hearing your rear cylinder in your left ear, and your front cylinder in your right.

The absolute best sounding exhaust (to this rider) has got to be trueduals with a dual-point circuitbreaker.

....Cotten

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Re: 56 FLH - Stay With "True" Dual or Convert to 2 Into 1?

#8

Post by PanPal » Thu Feb 19, 2009 5:05 pm

I run true duals on both of my pans. I like the sound a lot better, and noticed a performance change from the standard dual set up that was on it. This install took a lot of modifications. This one needed the rear pipe cut and angled properly to match the rear exhaust port and the front header needed an inch taken out below the front port connection and added to the squish pipe end. This squish pipe has no seem and had not mounting tab but that tab seems to always need relocated. The heat shield was added to cover welds. Running muffelers or creating backpressure is important so that the bike can be tuned as Kuda points out.

Now if I could only tune this CV.
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Re: 56 FLH - Stay With "True" Dual or Convert to 2 Into 1?

#9

Post by DaveSwanson » Thu Feb 19, 2009 6:41 pm

Thanks for all the good info. I was really leaning toward keeping it stock with the duals, and looking for any compelling arguments to switch to 2 into 1. The jury has come down on the side of duals. I am making a few phone calls trying to find a proper rear header.

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Re: 56 FLH - Stay With "True" Dual or Convert to 2 Into 1?

#10

Post by DaveSwanson » Fri Feb 20, 2009 4:38 pm

I called Harbor Vintage yesterday, talked to Dave and he dug a dual header up for me. It's on the way.

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Re: 56 FLH - Stay With "True" Dual or Convert to 2 Into 1?

#11

Post by keiser » Fri Feb 20, 2009 4:43 pm

So who still makes the true duals? I have a 60 Pan and would like duals but the only place I have seen that sells them is Paughco.

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Re: 56 FLH - Stay With "True" Dual or Convert to 2 Into 1?

#12

Post by DaveSwanson » Fri Feb 20, 2009 7:56 pm

keiser wrote:So who still makes the true duals? I have a 60 Pan and would like duals but the only place I have seen that sells them is Paughco.
I just saw a decent rear header for a Duo Glide on Ebay. Sold for about $75.

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Re: 56 FLH - Stay With "True" Dual or Convert to 2 Into 1?

#13

Post by LittleAl » Fri Feb 20, 2009 8:43 pm

I know this has probably been discussed to death and I've been reading some of the posts and the KB on exhausts but don't remember reading much if anything on the exhausts offered by NOS, any good?

I have OEM front & rear header pipe off eBay a while ago. I've been wondering if the squish back from NOS would work out with those. Seems like no matter what, even if all OEM it takes quite a bit of fitting.

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