Screw in intake manifold questions

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44dwarf
Posts: 11
Joined: 20 Jul 2019 12:20
Location: Winchendon Mass USA

Screw in intake manifold questions

Post by 44dwarf »

Hello all.
Due to my 3 1/2 being set up as a flat tracker it no longer has a air box the front cyl carb runs long the bottom of the tank those the intake has to be unscrewed part way. The old cast metal just isn't up to the abuse, I've read there is a Steel unit available but i don't know if it is the same two piece design with the three bolt pattern or not. Anyone have a picture of the steel unit 13.04.39?

Thanks for the help.
Vintage Flat Track Nationals coming up Sept 21 and 22 in Cuddybackville NY USA .
https://www.americanmotorcyclist.com/Ra ... hip-series
mbmm350s
Posts: 666
Joined: 22 Jun 2018 10:18
Location: Reading UK
Location: Berkshire UK

Re: Screw in intake manifold questions

Post by mbmm350s »

Hi,

The part you refer to is the screw in adaptor (steel) for use with the later post 1979 rubber inlet manifolds, the part you quoted is for standard 350 heads.
The rubber manifold is a push fit over the adaptor and the manifold secured by a hose-clip around a plastic stiffening part.
The carburettors can be fitted to the manifold, but an additional adaptor piece is required as the carburettor fits inside the manifold rather than outside.

Therefore to fit the carburettor you need the part you mention and the rubber manifolds and adaptors, clips etc, or you need to fabricate a suitable manifold.

I can upload a picture later if wanted but it is not a direct replacement for the original three part assembly so is probably not what you need.

Mark
mbmm350s
Posts: 666
Joined: 22 Jun 2018 10:18
Location: Reading UK
Location: Berkshire UK

Re: Screw in intake manifold questions

Post by mbmm350s »

Hi,

Here is a picture. This is the part you quoted.
Inlet_adaptor.jpg
Inlet_adaptor.jpg (145.72 KiB) Viewed 3278 times

Mark
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44dwarf
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Joined: 20 Jul 2019 12:20
Location: Winchendon Mass USA

Re: Screw in intake manifold questions

Post by 44dwarf »

Thank you for the picture that clears it up, as the other post I'd seen had a picture of a homemade tool a socket with some key stock welded to it.

My plan going forward is to use a copper hollow crush gasket under the tread just like in the exhaust to seal and help load the threads keeping thing tight with the lock nut.
The rubber mount would seem better but might not be worth the trouble for 4 - 8 rides a year.
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44dwarf
Posts: 11
Joined: 20 Jul 2019 12:20
Location: Winchendon Mass USA

Re: Screw in intake manifold questions

Post by 44dwarf »

Had some time this past weekend to work on the front carb spigot. I purchased several copper crush gaskets from BelMetric.com here in Billerica Mass part number GCA22x27 they fit the spigot end nicely but tend to walk around a bit so you must take care when tightening down on to them. I used a Strap wrench to tighten down and align the spigot. I crushed one with out noticing it had moved off center then took it out measured the cruch and looked to see if there was another copper or Aluminum washer that could be used but ended up just taking care to keep the ring centered as i tightened down. When i rechecked the Carb synchronization i was out close to 1 inch on mercury!
Bike runs well again, I'm excited to see how it goes on the track.

Tony
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