MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - Needle & Seat Leaks

I recently rebuilt my SU's using a Master Rebuild Kit from Moss Motors... All went very well and performance is vastly improved... It was the last task to complete after a complete engine rebuild... However, I noticed the smell of fuel after stopping the car in the garage after a wee run... The problem was easily found, since the fuel was dripping out of the overflow tube from the rear carb... I did some troubleshooting and found that the Needle & Seat in the cover of the rear carb bowl was allowing fuel to continue filling the bowl beyond the shut off of the Needle... It is, in fact, the Needle & Seat because after switching the Needle & Seat to the front bowl cover, the overflow was then from that overflow tube... Thank goodness that I have installed correct overflow tubes that are routed to a tube clamp on the front Engine Bearing Plate... I could very well have experienced a "thermal event" if there were short overflow tubes on the bowls...

Now that I have stated the problem, I have a question regarding the Needle & Seat... In the Moss Motors catalog there is a part number (371-060) for the standard Needle & Seat, of which (2) were supplied as part of the Master Rebuild Kit... There is also a part number(386-390)for a "Grose-Jet, Superior replacement for the orig. type needle & seat"... Can someone tell me what the physical difference is between the "Original Type" and the "Grose-Jet"... Also, I find it interesting that Moss Motors points out that the Grose-Jet is "Superior" but they supply the "Original Type" in the Master Rebuild Kit... The Grose-Jet is also about $3.00 cheaper than the "Original Type" Needle & Seat...

Any words of wisdom, from those with a similar experience would be appreciated... I am about to order a couple of Grose-Jet replacements for the NEW Needle & Seats supplied in my Master Rebuild Kit...

Cheers,

Rod Macleod - '55 TF 1500 - HDB46/6798 - "Molly"

Rod Macleod

Rod, the Grose-Jet uses a ball in a vertical cage to shut off the fuel flow. IMHO, they are the better way to go. There is probably a web site that can be found to describe them. Try a search. They are available for a number of different carburetors and go for rediculous prices on eBay.
Bud Krueger

Bud, thanks for the quick response... I agree, the ball would be a better design, given that it will have the ability to rotate and be "self centering" so to speak... I assume that it will still be actuated by the float and lever, as does the Needle & Seat arrangement...

Rod Macleod
Rod Macleod

Rod - The Gross jet sits higher in the float chamber so the float lever has to be reset to get the proper fuel level in the chamber. The Gross jet valve actually has two ball bearings in it, the large one that is seen protrudig from the bottom of it and which acts on a smaller ball that actually acts as the valve. Be aware that some people have had bad luck with them, although I don't know what kind of problems they have had. Like Bud, I have had good luck with them and have them in both our TD and MGB. I did see a set in our daughter's MGBGT start sticking closed over time, but a new set is still working fine. Good luck - Dave
David DuBois

Rod, the technique for adjusting the fuel level (float height) with the Grose-Jet is performed by adding fiber washers under the threads so as to change the location of the lower ball. I believe the upper ball closes against a Viton seat. Coincidentaly, they're made here in Mass. The problem mechanism seems to be from deposits formed on the ball due to fuel additives. I've had them in my TD for 10 years and just replaced the originals last year because it seemed that one wasn't closing completely.
Bud Krueger

Bud & David,

Thank you for all the info on the Grose Jets... I will be ordering them tomorrow, as replacements for the Needle & Seat type that I have recently installed... One works well but the other leaks badly... A 50% "failure rate" with new parts is a bit beyond my ability to be in a comfort zone with the Needle & Seat type...

Rod Macleod
Rod Macleod

This thread was discussed on 05/07/2005

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.