I have a minor issue on an otherwise near perfect car... on real hard cornering, my 72 E-type misfires a little bit. Not an electrical issue but purely carb. Another telltale sign is presence of fuel under the air filter, more or less depending on how severe the cornering / misfire was. One of them, the front right carb, is usually the one that's wet after hard cornering, usually only on hard left turns.

This week end at the slalom, it was a bit worst than usual with all 4 carbs spiling a bit of gas. it usually clears up quickly with hard accerleration on a straight but of course.. very little straight time on the JCNA course :-)

Float levels have been set lower, which has helped, but not completely. Are there any issues with Grosse jets being affected by side loads ? Carbs were rebuilt a couple of years ago, incl new floats, grosse jets, etc...

has anyone experience this?

Pascal Gademer
72 E-type 2+2
00 XKRCoupe
99 XJR

Submitted by NE52-32043 on Tue, 11/26/2002 - 11:31

Pascal,

You may have put your finger on the problem here. If you increase the pressure, it is possible that it is overcoming the grosse jets, causing the carbs to overfill. You should pull the return valve and clean it, make sure it is working properly, or if in doubt, get a new one. Then you can return the pressure to normal level and that may solve your problem with the carbs. Just a thought.

Steve Weinstein, JTC-NJ
'72 E-type 2+2
'89 XJS Coupe

Submitted by pascal@jcna.com on Mon, 11/25/2002 - 18:18

George,

I'm using the stock SU pump, with electronic kit.

a few months ago, I had to increase pressure by adjusting the spring to solve a slight fuel starvation that would occur only after running at high speed for 2 or 3 hours or more. apparently, when everything was real hot... the bypass valve would open too easily allowing fuel to return to the tank before filling the left carbs... that solved the problem.

The cornering issue was there before, and although it's been getting a bit worst lately, I can't say it did after I increased pressure. I'll try checking the float level as Steve suggested before puling the carb altogether.

Pascal

Submitted by cleavefamily@c… on Mon, 11/25/2002 - 16:09

Pascal,

I have the same problem with my 74 MGB with SU's and Gross Jets, but I think it developed recently (in the past year), after rebuilding them say 4-5 years ago. I think the floats are affected by centrifical force or maybe the Gross Jet springs have weakened. The car floods when I come into the parking lot at work a little hot when running late, i.e. a 90 degree or more turn at slalum speeds. Maybe the tabs on the floats bend after repeated centrifical force is applied. Tell me what you find out - I've learned to come into my parking space a little slower, but I suppose you don't want to run slalums slower do you?

Stew Cleave
JOCO Chief Judge
'69 E-Type 2+2
and other LBC's

Submitted by NE52-32043 on Mon, 11/25/2002 - 15:45

Pascal,

You still have the Zenith Stombergs on that car, don't you? Assuming that is the case, I had a problem with one of mine last summer, having rebuilt them last winter. A quick way to check them is to simply pull the dash pot off, remove the piston and turn the ignition switch to the run position (don't start the car). Look down through the jet from directly above (use a flashlight if necessary to visualize the surface of the gas) while the fuel pump brings pressure up.

The gas level should come up to just the very bottom of the jet tube and stop. If the tube on any of the carbs is filling higher, then the float needs to be adjusted. If fuel comes up and keeps going up, and pours out of the jet, then either the float is defective (could be sinking) or the grosse jet is not working for some reason (loose, clogged, defective). You'll need to pull the carb to adjust it or fix it. This can't be done effectively in place.

The ZS's should not spill fuel out of the jet, even under severe cornering since the fuel is all down in the bowl and is drawn up through the jet only by the negative pressure through the venturi. Cornering force or acceleration would tend to throw the gas to the side of the bowl, not up the jet.

Steve Weinstein, JTC-NJ
'72 E-type 2+2
'89 XJS Coupe