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Aluminum Carb spigots won't hold
Posted: Sun Jul 28, 2013 8:38 pm
by mattcfish
Having issues keeping my SJBMW aluminum Dellorto spigots in place. I've had them for many years, but I have a frustrating problem. Every long ride they loosen up. Tried Lock Tight, high temp gasket compound and even JB Weld. They hold for awhile but not permanently. Then, they're a real PITA to remove because of the gunk on the threads. Aside from welding, any other tricks out there?
Do the stainless versions from Motoren Israel.... etc. fair better? Can't use stock because I have /6 heads.
X
Posted: Sun Jul 28, 2013 11:28 pm
by Deleted User 62
Edit: Sorry, misunderstood question.
Re: Aluminum Carb spigots won't hold
Posted: Wed Jul 31, 2013 1:32 am
by mattcfish
I've decided to bite the bullet and ordered the Motoren Israel SS spigots. Never been too happy with the San Jose Aluminum ones, mainly because they are machined about 2mm short on the inside of the head. This leaves a noticeable gap that probably contributes to air leaks down the threads. Also creates a little bump in my smooth intake tract. Was thinking of having my aluminum spigots machined to insert deeper, but on close examination I've noticed they are starting to distort from vibration where the carb clamps on.
The Stainless ones from MI should be pretty tough and machined properly. Might as well replace while I have them out of the heads. I plan to seal them in with permanent lock tight and a little 300 degree Celsius Dirko sealer (applied on the outer most shoulder) that I've used on VW Vanagons.
I don't use the stock snorkel (part of my problem). Instead I have 70mm velocity stacks mounted inside some large K&N pods. Thinking of either going back to snorkels, or creating stabilizing brackets for the carbs so they don't put twisting force on the spigots.
Re: Aluminum Carb spigots won't hold
Posted: Wed Jul 31, 2013 3:30 am
by chasbmw
I use SS spigots, originally made by Keith Shaw in the UK, they only came loose a couple of times and now have been stable for a number of years.
I did get the spigots machined so I could rubber mount the Dells, this further insulates them against heat and vibration, helps them stay in tune for the long term. Not good for pod filter though, as you really need support on both ends of the carbs.
Re: Aluminum Carb spigots won't hold
Posted: Fri Aug 02, 2013 2:45 pm
by mattcfish
chasbmw wrote:I use SS spigots, originally made by Keith Shaw in the UK, they only came loose a couple of times and now have been stable for a number of years.
I did get the spigots machined so I could rubber mount the Dells, this further insulates them against heat and vibration, helps them stay in tune for the long term. Not good for pod filter though, as you really need support on both ends of the carbs.
I was thinking of machining the shoulder of the spigot to take a Viton O-ring. Any thoughts?
Re: Aluminum Carb spigots won't hold
Posted: Fri Aug 02, 2013 5:33 pm
by chasbmw
Will the viton handle the fuel and temperature loads?
Is this to fill in a gap left when you screw the spigot tight?
Charles
Re: Aluminum Carb spigots won't hold
Posted: Fri Aug 02, 2013 8:25 pm
by Jean
Viton can handle anything neoprene can and more.
It's good to contain some pretty nasty stuff...
Re: Aluminum Carb spigots won't hold
Posted: Fri Aug 02, 2013 9:33 pm
by melville
Any reason a wee tackweld wouldn't do it?
Re: Aluminum Carb spigots won't hold
Posted: Fri Aug 02, 2013 11:53 pm
by mattcfish
melville wrote:Any reason a wee tackweld wouldn't do it?
Don't have aluminum welding capability.
I've got some ideas for some adjustable brackets that will hold the carb steady to prevent twisting force during vibration.
Re: Aluminum Carb spigots won't hold
Posted: Fri Aug 02, 2013 11:59 pm
by mattcfish
chasbmw wrote:Will the viton handle the fuel and temperature loads?
Is this to fill in a gap left when you screw the spigot tight?
Charles
I'm hoping the MI spigots won't have any gaps. The o-ring would insure against any air leaks caused during expansion and contraction due to heat, and would provide a little grip and resistance to prevent backing out.
The Viton o-rings are good to at least 400F and are resistant to most everything you can throw at them.
http://www.theoringstore.com/index.php? ... ath=368_65