dual idf 40's exhaust questions

[ctdukefan]

I've just added dual idf 40's to my freshly built 1641. Was doing a little reading and saw some comments that you can't run dual exhaust with dual carbs. Is this true? I have chrome empi dual exhaust with baffles. Can I keep it or need an exhaust with more back pressure? Any help is appreciated, thanks

[jsturtlebuggy]

Some times the dual exhaust will interfere with the intake manifolds or carbs. They usually sit closer to the heads.
I have no idea which work and which ones do not.
The only way to really know is to mock it up to see it there is any interference.
I switch to a 4 into 1 systems back in the early 1970s. Duals do not make as much power as a 4 into 1 system.
Yes some people like them for the sound and they way they look. Just know you are giving away power you may need.
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Joseph
Fair Oaks/Orangevale, CA
Elrod Motorsports
Motion Tire Motorsports
Having fun with Dune Buggies since 1970
Into Volkswagens since 1960

[Glenn]

Are you talking about this type of exhaust, if so it's just about the worst system you can use, from a performance point of view.

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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
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[ctdukefan]

Yes, I have similar dual exhaust, carbs dont interfere at all. Its all together and almost ready to put engine back in. Do I need to worry about lsck of back pressure?

[Glenn]

[jsturtlebuggy]

Not really will you notice anything at lower RPM, as compared to a stock muffler.
When my Dad built our first street legal fiberglass buggy back in 1970, we installed a set of chrome glass pack ones.
My Dad called them "A Cop Calling Stereo System". They were not quiet by any means. My Mother was followed home several times by law officers. When they seen who was driving, they would just drive pass the house. It was not until a year later when started playing with sand buggies that we discovered a four into one system helped with power through the whole RPM range.
_________________
Joseph
Fair Oaks/Orangevale, CA
Elrod Motorsports
Motion Tire Motorsports
Having fun with Dune Buggies since 1970
Into Volkswagens since 1960

[manxdavid]

It's not 'back pressure' that you want, it's some semblance of tuned pipe length along with the scavenging affect that a 4 into 1 collector gives. IMO fit what you've got (if indeed they do fit) and see if you're happy with the performance they give. As long as you've not gone too wild cam-wise (cam overlap adds a lot of noise and cackle to an engine) it shouldn't be too loud (depending on how you drive of course).

BTW those dual 40's will need careful jetting and setting up preferably on a rolling road as they're a little big for a 1641 unit. 36's would have been a better choice IMHO.

[jrailer]

I would be more worried about over carburetion

[jspbtown]

There are two designs of those style exhaust. One fits dual carbs one does not.

[ctdukefan]

Any jetting recomendations? This is new to me. Love the lookn gonna make it work[/img]

[Dale M.]

If comment you were reading were generalized, it is wrong.... There are many different dual carburetor systems and a hundred or more exhaust systems that will work, trick is to get best combination.... Generally small engines use smaller diameter pipe (1-1/4 to 1-3/8 in.) exhaust systems and large engine use larger diameter pipes(1-1/2 in. or more ) ... Exhaust system system which have equal length pips are more efficient as length of pipes help scavenging effect (not tuned like cone mufflers on 2 strokes) when merging 4 into 1, and then you have choices of muffler types (quiet to loud) or cone shaped stinger....

Although dual cannons look cool and you can run them, but as others mentioned there is "some" power loss, and they sound like a pair of out of tune Harleys running side by side... And what you get for mufflers is what you get...

Dale
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“Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.

"Kellison Sand Piper Roadster" For Street & Show.
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All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ...

[Dale M.]