Weber Riding Ass-Backward in the Saddle

[difrangia]

I have a question regarding mounting a carb ass-backward on an engine. I'm re-building the E1 in our 320 pickup and am looking ahead on a couple of issues. I have a DGAV (electric choke) on the shelf and did a little preliminary fit up to look at clearances. This photo shows the carb sitting on manifold adapter in the normal orientation.

 

 

 

Obvious that this is a no-go. The choke unit is inside the rocker cover and on top of the pushrods & rocker assembly. It is now obvious why the Pierce manifold for the E1/J13 engine has longer intake runners. I'd like to use the stock manifold and keep the original carb heated by exhaust.

 

Here is a shot with the carb turned around.

 

 

Just a bit over an inch of clearance. This throws the primary barrel next to the head. The mounting ports in the manifold are about the same size; & I might open up a bit anyway. Can any of the expert gearheads here tell me why this won't work? I've no problem with fabing the linkage and doing the plumbing. This also puts the idle-air adjustment on the side away from the rocker cover as a small bonus. Looks like a win-win unless someone can tell me why it won't work,

 

I actually bought this carb for the 620 and haven't gotten around to mounting it yet and I haven't decided whether to use an electric or manual choke on the 320 pickup if I decide to go with a Weber. I believe the manual mechanism sticks out from the carb body close to the same amount on the Webers. Thanks in advance for advice & opinions.

 

steve

[laotsu]

I ran a DFAV Weber backwards on an L16 intake for years with no problems.

[datzenmike]

All L series run the primary closest to the head... it's fine.

[difrangia]

Head in arse again. With carb on backwards, the primary barrel would be away from the engine.

[wayno]

It actually depends on which way you install the adapter, but you can also buy a manifold from these guys, I would think they sell just the manifold, see how it sticks out farther from the head than the stock manifold, but it leaves a big hole in the exhaust manifold that you will have to make a plate to block it off.

Call them and tell them what you want, I could not find this package on their site, but the guy I talked to knew exactly what I needed.

http://www.piercemanifolds.com/

[Stoffregen Motorsports]

I believe the float position can be affected by hard accel/decel, which is why the carb was positioned with the float bowl towards the front of the car/truck. I don't believe this would effect 90% of the users though. Try it out and let us know how it works.

 

Oh, you may need to do a bit of work inside the manifold to get the adapter matched in it's new orientation. That's nothing that a carbide burr and 20 minutes can't fix.

[datzenmike]

Head in arse again. With carb on backwards, the primary barrel would be away from the engine.

 

Well then all Z series engines have the primary away from the head. :lol:

[difrangia]

Right the smaller primary bore is away from engine on 620.

 

Working from memory and without going out to the shop to verify, I believe that the ports at the carb mounting flange are the same size and there is room to do a little opening up and shaping.

 

I read a thread on here last week that that featured a pickup with the Pierce manifold installed.

 

http://community.ratsun.net/topic/45401-another-320-new-owner-65/

 

I do want to keep the carb heat feature.

 

As for driving forces on the float assembly, that was one of my main considerations in posting this and picking heads. I'd have no problem with doing the mechanical chores if it will work in driveability. Without taking the top off the Weber, I have no idea about the float arrangement and how that might relate to the inertia of accelerating, stopping, cornering but I won't be doing any two-wheeling in the little pickup.

 

Unless someone comes up with a bad experience with rotated carbs applied to the kind of vehicle and driving that I will be doing, I'll probably go for the backward carb and post results. It'll be a while before I cross that bridge. Engine machine work, coatings on some parts, and clean/update of the engine room will take a month or two.

 

Miles to go before I sleep.

 

Steve

[datzenmike]

Assuming the linkage side on the 32/36 is the back of the carb... the float hinge is to the rear of the float bowl with the floats ahead of it. Under extreme braking deceleration the fuel will slosh forward and under extreme acceleration slosh backwards. How much this will affect the floats I don't know but you don't here of many people posting that their weber starves or floods when braking. The correct float height is essential.

 

The stock air cleaner has warmed air feature. Exhaust heat is available in just a minute or two and this will help a cold engine evaporate the fuel in the manifold and run much smoother in cold weather. In addition carb icing is eliminated where temps drop near or below zero and there is high humidity. I have experienced carb icing and it almost always happens during freezing rain events.

 

That pierce intake, and maybe all E1 engines? doesn't have a coolant warmed/cooled intake either.

[difrangia]

The float on the original Nikki is on the right (engine) side. I may be wrong but I seriously doubt that the driving forces that the 1200cc 320 pickup experience will be severe enough to cause a problem with the float operation.

 

Curiosity got the best of me and I made a trudge out to the shop. On the original Nikki and on the Weber, the primary is on the side closest to the engine when mounted with the operating cable toward the firewall, as is normal. Whew! Glad to be over that one.

 

The 620 has intake air heating from the exhaust manifold shrouding but the 320 does not; the 320 just pulls in whatever is ambient in the engine room at any given time. Semi-stone Age 'Pleasantville' technology.

 

Steve

[datzenmike]

I think my old 510 had a lever marked summer/winter on the snorkle to select warm air from the manifold. :lol: