Carb Direction Reversal

[hanleyclifford]

After reading that it is impossible to turn the Zenith carb around on the other site, http://gtgravelyparts.com/zenithcarbs.html , I decided to test that hypothesis with some of my spares. The biggie is changing the throttle lever and stops both for idle and WOT. It involves grinding away both ends of the (barrel?) rivet and re-assembling for service on the other side; of course, this will mean pushing to open the throttle, but that can be engineered. Question I have for the metal workers; can I re-assemble the throttle lever assembly with silver solder? Note the "splined" nature of the connection.

[joe_db]

I have to ask - why?
Is this for an A4 or just for fun or what.

[hanleyclifford]

I have to ask - why?
Is this for an A4 or just for fun or what.

Good questions. Turning the carb around on the A4 would make main jet and idle screw adjustments much easier, and yes, it is fun.

[BadaBing]

Hehe. Nothing like being told "it can't be done" to start the wheels turning.

Are you planning to let the folks at GT Ent. know that they are now mistaken on two claims?

[Dave Neptune]

Hanley, silver solder is probably the absolute best way and it is easily reversable. Just don't point the torch at yourself when reversing.

Dave Neptune

[thatch]

We know that our carbs and engines are okay at angles up to 15 degrees, but it might be a good idea to find out if the float is going to work properly at 15 degrees in the opposite direction.
Tom

[Dave Neptune]

As per Thatch, the carb is center fed so to minimize any float level discrepancies be sure the floats a parallel to the body when proper height is achieved. The floats are pretty concentric and until steeper than 20* angles are accounted for as far as testing 15* either direction should be OK.

Perhaps someone will tilt a bench motor to duplicate 20* BACKWARDS and note any issues. Never really looked that close for steep angles, have on some off road stuff for sure though.

Dave Neptune

[BadaBing]

I'm growing more interested in the idea of what a slightly smaller venturi would do. This is primarily based of Dave's previous comments about our carbs. In another thread. Having said that I know I would have any actual way to test any possible change and seeing that we really are not going to, or need to, gain any HP it's just a winter daydream.

[hanleyclifford]

I'm growing more interested in the idea of what a slightly smaller venturi would do. This is primarily based of Dave's previous comments about our carbs. In another thread. Having said that I know I would have any actual way to test any possible change and seeing that we really are not going to, or need to, gain any HP it's just a winter daydream.

There used to be an insert for Canadian applications which reduced available horsepower to meet a governmental standard. I had one but took it off and cannot find it. I bet Dave has one.

[Bratina]

There used to be an insert for Canadian applications which reduced available horsepower to meet a governmental standard. I had one but took it off and cannot find it. I bet Dave has one.

Sorry for the drift - I have a Canadian A4 and always meant to check for that insert. Do you remember if it's obvious? I've had the carb off any number of times but don't remember ever seeing an insert. Maybe a PO removed it already.

[hanleyclifford]

Sorry for the drift - I have a Canadian A4 and always meant to check for that insert. Do you remember if it's obvious? I've had the carb off any number of times but don't remember ever seeing an insert. Maybe a PO removed it already.

Measure the diameter of your carb opening at the throttle bore; if it's less than 1", the insert is present.

[tenders]

Sorry for the drift - I have a Canadian A4 and always meant to check for that insert. Do you remember if it's obvious? I've had the carb off any number of times but don't remember ever seeing an insert. Maybe a PO removed it already.

I believe that insert reduced the A4 HP from 30 down to 25, to avoid some kind of Canadian tariff on large engines, and is what designated the engine an Atomic "Stevedore" rather than an A4.

[hanleyclifford]

Turning the carb around has become an interesting project and I have learned some new things. For one thing, the early carb with it's removable linkage has proved to be a simpler project so I did one of them first. Moving the linkage was easy, as was installing a second stop pin on the opposite side. But it was necessary to drill and tap the idle/WOT linkage cam for another adjusting screw. Also, in order to get a good seal in the throttle body the throttle plate itself had to be flipped as the picture shows. Fuel will have to enter from the (new) front as shown since the casting does not easily allow for another opening opposite the original fuel inlet (solid cast iron!). The choke and throttle rod bushings and end cap were an easy flip. I have come to appreciate how much better quality the early carbs represent. I might switch.

[hanleyclifford]

The late 5 hole carb proved to be just as easy to convert, but using the linkage from the early carb which reversal and installation requires no soldering. First the block is prepared for the application: the front oil pressure hole can now be abandoned; and it was always a PIA in proximity to the motor mount, flywheel housing bolt and oil pan bolt. With the carb reversal the middle hole becomes viable for oil pressure take off. Next hole to right is oil pickup for cooler/filter, next the return for oil cooler/filter loop.

[hanleyclifford]

Next the carb is installed. Note the linkage from early carb.