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 MGA - Grose Jet Valves

I am replacing my MGA's engine with a rebuilt 1600 with ported head and lightened flywheel. I am giving thought to grose jet valves vs. standard in the S.U. carbs. I have read that the grose jet valves are less prone to sticking and, therefore, help reduce flooding of the float chambers. Is this a worthwhile improvement, or do the grose jet valves eventually start to stick as well? Are there any other benefits to the grose jet valves?

Regards,
M.D.
'57 Coupe
M. D.

Hi MD. I have been running Grose Jets for many years, and am extremely happy with them. Before the Grose jets, I had flooding problems due to dirt in my fuel tank. After the Grose jets were installed the flooding problems disappeared. An inline fuel filter fitted before the carbs was extra insurance against rust particles Clogging the Grose jets. I highly recommend Grose jets to anyone with SU carbs. Cheers! GLenn
Glenn

MD,

I used them when they first came out, years ago. I plan to use them in my current restoration.

Larry
Larry Gray

MD - Like the others, I have used the Gross Jets for a long period of time in both our TD and MGB and have had excelent success with them, while others have not had much luck with them at all. I have some pictures and a write up that expalins how to modify the float lever in your carburetor float bowl to stop the needles from sticking in the folat bowl after the car has sat for long periods of time that I can send to you if you will send me your e-mail address. Basically it involves setting the drop setting of the float lever such that it doesn't drop so far that it will catch the needle at such an angle that it jams aginst the lever. Cheers - Dave
David DuBois

M.D.
Like Glenn and Larry I have used them for many years because they have done what they claimed. Not everyone who has ever used them will agree, but my own experiences have been consistently good over a long time, and that is really all I have to go by. I sometimes wonder if the problems claimed by some with their use of them stems from other problems we don't always get to hear about as follow up. Or maybe it is just luck.
Bob Muenchausen

I will add my views on grose jets to give the other side of the story. On the way from MG 2001 to St. Louis in convoy with a friend we stopped to get gas. This proved to be bad gas with what appeared to be sand suspended in it. The sand scratched the ball valve inside the grose jets on our friend's car so badly it would not seal and the float chamber kept overflowing.

Yes, a fuel filter was fitted to the car but the sand was fine enough to pass through that before destroying the jet.

I know this is something that does not happen every day but I have had bad gas pass through a regular needle valve without any problems in the past.

Because of the damage caused I will not use grose jets, I rebuilt my MGB Zenith carb not long ago and threw out the grose jet supplied with the kit, I sourced a regular needle type to use instead.

I have been driving many LBCs for 20 years and have only had a carb flood on me once, I am quite happy with the performance of the orginal jets.
The Wiz

If you completely refurbish your existing carbs or replace them with new ones, you don't need grose jets; the OEM jets do the job.
Arthur DiLello

I experienced a harmonic vibration around 4500 rpm ('64 B) that shut the fuel off using the gross jets. Went back to the original needle valves and issue went away. What would be nice is if someone knew the part number for the Viton tipped needle valves. The viton lasts much longer, I'm told.

Paul Hanley

Thanks all. Hearing both sides of the debate is certainly helpful. I think I will stick with the standard jets for now. I can always switch later if issues arise.

Regards,
M.D.
'57 Coupe
M. D.

If there is a source for the Viton tipped valves, go for it! I used those for longer than the Grose Jets and had equally as good luck with them.

"Standard" valves have come in so many differing configurations and materials over the years that it is not surprizing to me that there has been such variance in the luck folks have had with them. I have had sets that worked just fine and others that weren't worth a hoot in a whirlwind, but on most all cars I have had, Viton tipped float valves were far more consistent than those that weren't, and Grose Jets? well, lets just call it the luck of the draw that the ones I have used have been as consistent as they have been.
Bob Muenchausen

Does anyone know if S.U. guru Joe Curto sells viton-tipped needle valves?

M.D.
'57 Coupe
M. D.

MD - E-mail him and ask. JoeCurto@aol.com Good luck - Dave
David DuBois

Joe Curto does sell the viton tipped valves.
John Heisenfeldt

This thread was discussed on 03/06/2005

MG MGA index

This thread is from the archive. The Live MG MGA BBS is active now.