I am still chasing a strange "hesitation" with this carb where power drops off, but immediately picks backup. Am suspicious of a vacuum leak, but certainly cannot find one.
Also had to:
1. replace the mainfold studs for more length to retain use of the phenolic spacer due to a much thicker carburetor base
2. mill out some clearance in the flame arrestor housing due to interference with the larger fuel inlet "hump"
3. the hole for the hand throttle hohsing required drilling larger, but my hand throttle is not OEM so that is probably on me.
I opted NOT to return my original carb for the core charge refund "just-in-case".
Hello amphibifriends. Long time since I was here but Cameron mentioned talk of carburetors !
My daily driver Amphicar has a big Weber and a 1300 engine but on my other Amphicars I still prefer the original Solex or Zenith.
Over the winter I found a few 30IZs new and boxed. When it gets a bit warmer I'll check them on my engine test rig and then offer them for sale.
All the NOS ones do need testing as in the past people regularly opened them up to "borrow" jets!
Mike I know you are after one so you are top of my list to get in touch with !
I think I'll end up with 4 or 5 for sale, not sure what price will be but it won't be outrageous, likely less than the other options.
Hi David, is the venturi diameter 22mm like the Solex B30 PSEI carburettor factory mounted in Amphicars? I am asking because i have Solex carburettors looking similar to your Zenith, but venturi diameter is 17mm.
Hi, yes all these new ones are 22. I've also got a 24 somewhere and that worked well. You're right you really don't want less than 22 on Amphicar. The smaller venturi were for cars like the Reliant that were under 1000cc. I need to check the jets but I have a box of spares to swop around so should be able to get these 22s to work well. Amphicar used a very early version of the Herald 1147cc engine with a camshaft that had minimal lift (known as a 12-52 cam) that needs a smallish main jet or it tends to flood. Later on Triumph used a cam called an 18-58 that gives significantly more power, that's a great upgrade if you are rebuilding one of these engines and 18-58 cams are not impossible to find.
I should clarify the Solex Zenith thing. By the time Amphicar was made they were really the same company, like Austin and Morris. Originally Solex was French and Zenith British but Zenith built Solex under licence and fitted them to many British cars in the 1960s, certainly most of the Triumph range. So the original Amphicar carb had a Solex badge but was made in the UK by Zenith. Later on when the aftermarket and tuning market got really big the company, at least in the UK, started selling under the Zenith name (Zenith meaning pinnacle or highest point) and the adverts said "upgrade from a Solex to a Zenith" but really they were the same product- although some versions of Zenith carbs had improvements like an "econostat" that shut off the fuel supply on the overrun to improve economy. The Zenith 30 IZ was sold as the replacement for the original B30PSEI fitted to Amphicar. They have a little brass tag on them with a 4 digit number which shows the original jetting.
Thanks all i know about the Triumph engine is from your website.
I have 2 B30 PSEI housings with 23mm venturi on the shelf, that could work. Somewhen. As there are 2 complete original carburetors besides.
Jon, that sounds like the slow running jet is blocked, a common problem, it's the smallest jet in the carb, pull it out and give it a blast with compressed air. Could also be adjustment with the screws on the base of carb.
Keep in mind the profound up & down “hunting” at idle only happens when the motor is hot.
I was thinking maybe a vacuum or fuel line air leak from something not “quite” tightened, introducing a problem after heat expands things.
(I would think a blockage would cause the problem all the time, no?)
And were are the various jets? I have no knowledge of jets or their locations -just a recollection of warnings that they are tiny/easy to lose, and chidings of “the settings are critical and you don't wanna screw with them”
Thats why i was askibg about new carbs. I will admit the brass fuel inlet tube thread “bubble” has a slightly deformed seat inside the top of the carb...so when installing it after my local shop put in the rebuild parts(accel pump diaph, etc) i made sure to put fuel resistant white ptfe sealant on the threads of that inlet connection.
But i do see little brown areas of fuel residue in a couple areas at the base of the carb—being old , are they a bit poor tolerance/leaky ?
Jon, Just needs a clean and setting up. To get idle right you need to adjust those screws held by springs. There are loads of printed guides, I'll see if I can find something online. Here you go, not complete but covers most of it.
Well, Gerry obara, Gord Souter and Dave Derer all tinkered with (i think) the idle adjust screw - at the base of the carb. It continued to have the varying-idle/near stalling issue when hot. So other than that scre near the base, what do i need to do? Total amateur here! Maybe a video to show me, done on one of your bench-carbs?
I purchased a new carb from Gordon Imports earlier this year and got around to installing it recently. It ran fine out of the box except after warming up it would stall as I slowed down, such as when approaching a stop. I didn't have any vacuum leaks such as at the head to intake manifold joint. Leaning out the idle mixture screw (knurled one at carb base) a bit smoothed it out and the problem went away. Hot starts are no longer an issue; overall it's much better than the earlier carburetor. I turned the screw clockwise to lean it, then backed it off when it ran a bit rough. Ideally I'd have used an exhaust gas analyzer but I don't have access to one, you can do it by ear in a few minutes.