Melted velocity stacks

[Jamesrlong]

Anyone know what would cause my velocity stacks to do this?

[JJ 911SC]

Major backfire???

[Jamesrlong]

Thanks, I know they need to be replaced but should I replace them before I adjust the carburetor and valves?

[jpnovak]

lean pop starting fire in intake.

Get everything adjusted. Not only bad for plastic velocity stacks but bad for your engine to run lean. They won't cause any issue to run for a period of time unless the plastic if flaking off.

[Jamesrlong]

Thanks

[jpnovak]

Are both sides doing this? Only one side points to a linkage adjustment problem. The carbs would need to be balanced L to R.

[Jamesrlong]

Both sides are doing it but the left side is quite a bit worse than the right side. I've ordered a carb calibration gauge, should be here tomorrow or Thursday, so that's my next project. Adjusting and balancing the carbs. This is actually my first carbed car, and I've probably picked one of the most complicated cars to learn carb adjustment on.

[Daves911L]

Yup, plenty of fuel vapor floating around above those stacks, and any little lean pop lights it right off. Just a quick flash, but repeated often enough and there you go. These plastic stacks melted back when the cars were new, too.

But, to the contrary, you are fortunate to have Webers to play with. Very simple and straightforward to tune. No magic or mystery. Lots of good information available out there to guide you. Get them running correctly, observe proper start-up procedure, and replace them with metal stacks cause no matter what you do its still gonna pop now and then.

[Jamesrlong]

Yea I've found so much info on how to adjust them. I think it's that there are 6 barrels to tune that makes them seem complicated. Anyone know where you can get metal stacks for these, I didn't see them avaliable from pelican?

[70basket]

Look up alfa 1750's eBay store. If you don't see them send a email he has come with some new parts for my Zeniths that many folks said were NLA. Good luck

[gamin]

************ has the metal 40mm air horns for weber or zenith. ************.com. Not cheap.

[jpnovak]

same as VW 40idf. Easy to find at reasonable prices.