Float overflow

[mrpatatomoto]

I bought a different carb because the shop said I needed a new needle and seat, and the carb was cheaper. But now when the car idles down fuel comes out the air intake.
I have adjusted the float multiple times to no success. My guess is the inlet valve is sticking but I have taken it out and it seems in working condition.

Any suggestions before I buy another inlet valve?

~Mike
1975 TR7 FHC

[Workshop Help]

Yes, buy a 'Gross Jet'. Set the float level to about 5/8" from the top of the carburetor(s) bare flange to the top of the float.

It does no good to examine the stock float needle as it is masked by the screen and the needle is not removable from it's body. If you do get the needle out, the entire little assembly is trashed.

Face the bitter facts of life. You and me and everyone else here are owners of old sports cars. It is entirely right and proper for items like float needles to be at the end of their expected service life and in need or replacement.

Mildred Hargis

[Hasbeen]

Have you done any other work on the fuel system, like a new filter, or work/cleaning/replacement of the pump itself. If so you may have increased the fuel pressure.

The Zenith carbs, as with the SUs can not handle more than 2 PSI fuel pressure, where as many US carbs run up near or above 4 PSI. If you did something to increase your fuel pressure, that is possibly why you had what ever your previous problem was.

I suggest you get your fuel pressure checked, & corrected to 2 PSI if it is out.

I have never had a needle & seat stick, unless full of gum from evaporated petrol. If they leak, & there is no problem with the float, it is usually needle wear that causes it.

Incidentally, I have rarely found a second hand item worked satisfactorily, unless it was overhauled, although some may be lucky. I have found overhauling what I have usually works well, & is often the cheapest way. also the last time I bought a needle & seat for a carb, [the SU & Zenith float needle & seats are interchangeable], it cost no more than $10, but it a few years back. Fitting would be much more expensive if you didn't do it yourself.

Hasbeen

[mrpatatomoto]

Yes, I have replaced the filter and added in an Electric pump with a pressure regulator set to 1psi(untested)

Single Stromberg When I looked I couldnt find a new needle/seat

~Mike
1975 TR7 FHC

[Hasbeen]

That sure sounds like excess pressure to me. If your carb starts flooding straight after modifying the fuel system, it is a pretty fair chance it is your recent modification causing it.

This is particularly the case with fuel systems in the US where most local carbs run at much higher pressure, & most mechanics are not aware of this difference. Most electric pumps marketed in the US would be set for US cars, that require 4 PSI.

I reckon you'll find your old carb will be fine once you get the pressure right, unless it was playing up before the pump change.

Why did you change the pump?

Good luck with the regulator, I hope you have more success with it than I have had. The ones I have tried tend to block up with the least bit of dirt, when restricted to 2 PSI. I have no idea how you set the pressure, without a gauge to tell you what it is, but maybe some are clever enough.

Incidentally, with the standard mechanical pump I have found the twin carb car suffers fuel starvation, once the fuel pressure drops below 1.7 PSI. The twin carb car is of course a different animal, so this may not be the case with yours. I had assumed the float chamber needle & seat could not pass enough fuel at the low pressure, but then I was wrong about something before.

Hasbeen

[HDRider]

Many of the fuel pressure regulators only limit the pressure when the fuel flow is high enough. When the flow is slow or stopped you will get full working presure from the pump. As the fuel flow at idle is very low on a 7 this could be your problem.

I have also seen issues with micro fine rust particals holding the float valves slightly open. The particals are so small that they will pass through the fuel filter. The only cure I know of is to drive the car enough to clear the system, probasbly about 1,000 miles, or have the tank professionally cleaned.

Edward Hamer
Petaluma CA

[Workshop Help]

My dearest Edward, please peruse the V-B catalog. My Summer 2013 edition, TR.64, on Page 56 details the parts available for the 1975-1976 California model single carburetor. The inlet needle valve, Part # 3-361 is shown priced at $16.95. On Page 58 is listed the 'Grose Jet', Part # 3-592, priced at $11.95.

Providing you are practicing clean living and thinking pure thoughts, the float bowl gasket may come off cleanly and be reusable. If not, a new float bowl gasket will be needed. V-B does not appear to sell them separately, tho they are included in the carb rebuild kit which shows to include a inlet needle valve, for $38.95, Part # 3-957.

All these prices do not include their shipping costs which are listed in the back of the catalog and are not cheap.

Mildred Hargis