Dual pipes, I understand there are two types

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Dual pipes, I understand there are two types


Post by suicideshovel65 » Wed Dec 01, 2004 10:58 am

Hi there everyone, a quick question about true dual pipes (with the crossover). I understand there are two types - pre-58, and 58-64?
Can anyone describe the basic difference (especially with the rear crossover), and recommend which would be better for my setup?
I'm running a '49 engine in a 58-64 frame. I'm figuring that the pipes might be made to match the frame configuration - particularly clearance around the downtube - but am unsure if there might be any differences at the head manifolds for example - different angles to the spigots or similar.

One other question - do all of the years of head castings have the same exhaust spigot angles and dimensions? I ask because the 50 castings I have (NB with repaired spigots) seemed to be at a different angle to the 48 castings (repairs unknown), which necessitated a lot of fartarsing about with the headers (cut and reweld).



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Re: Dual pipes


Post by PanPal » Wed Dec 01, 2004 7:50 pm

I just did this on my 59. I don't know about the 49 head exhaust port angle ???. I had tried one pipe from stock before buying the 58 to 64 pipe. The one I had was Pre Duo Glide and the exhaust port and pipe would not line up correctly. I THINK the exhaust ports are at different angles. (NOT SURE) It may be you need a 48 to 57 pipe judging from what I was looking at with one in place on my 59. It crossed thru the frame ok but the exhaust port would not line up, the straight portion of the pipe that attached to the mufflers was a little skewed, but would work.
Wanting to get my running restoration project on the road, I had to install what was available at the time and this was a 65 and up pipe. This pipe will stick out too far past the primary cover and has a mounting tab for the 65 and up primary cover. It fits but it aint pretty!
If someone can confirm that the exhaust ports are at the same angle on a 49 head as they are on a 58 to 62 head (63 and 64 heads are the same except for the outside oiler holes). You would need the 58 to 64 pipe. I don't think either will be a perfect fit. I think it's a little problem with the frame difference and a lot depends on the port angle. If the ports on your heads were worked on, it may be that they have already modified the port angle to match a 56 casting number (58 to 64) head to get your motor to work in your frame.
I can say I am very happy with the true dual set up. I no longer have problems with the rear pipe working it's way off the port. You will need to remove the regulator, the inner and outer primary covers, both foot boards, and the external oil filter and lines to get it in there. May as well check your head bolts while everything is out of the way! Remember to loosen the top motor mount before torqueing the head or base bolts.

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