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MG TD TF 1500 - Gross Jets NG

Why are the Gross jets supposed to be so good? I'm on my second set and one of the damn things is leaking again. Happened on the first set and now the second. Glad I have the long overflow lines that ends below the front of the sump! I just ordered a set of viton tipped conventional type and will throw these crappy gross jets in the trash. I tried rolling the ball on my finger to help it seat better, but that was of no use. Two sets, no more. Live and learn. PJ
Paul161

Yeah Paul....I have read about problems with the newer Gross-Jets. Sorting a High Speed cutout on the '67, I passed over the mounted Gross-Jets initially, thinking they couldn't be the problem. Now, the second time around, I find I have the opposite problem from you. I can blow into the Delivery Port, and every once in a while, the Ball sticks and inhibits air flow. You have to blow harder to unseat the Ball. Turns out....this is STILL not my problem....but I'm not putting the Gross-Jets back in. I installed some Brass SU ones.
What was your symptom? fuel pump ticking away....or the smell of Fuel?

Mike TF-8257
M Brand

On both occasions the pump wouldn't shut off due to fuel bypassing the jets. On one occasion it flooded the engine while running. PJ
Paul161

I wonder what opinion Dave Braun or Joe Curto have on the subject.
tables1

Well really, if someone has good luck with a product and it works well, it's a good product in their mind, but on the other hand, if it doesn't, it's a waste of money. Sometimes change isn't the best policy. I tried twice and had problems.
My car, at one time in the past, had an engine fire, A patched up warped side panel and buckled bonnet on the carb side told the story. I believe a crash developed from this incident ruining the right wing, running board and door also showing cable marks on the front, possibly from the old style guard rails. Reason I'm very cautious about gas leaks of any kind. PJ
Paul161

Gross jets used to be a very good product, but somewhere along the line the product got dropped in the mud. I believe the original maker sold out fairly recently (the past 10 years or so) and the result has been less than stellar - read, they are junk now days. Just use the standard viton tip needle valves. Cheers - Dave
DW DuBois

I've heard more complaints than praise about grose jets over the years. A few guys have had good luck and swear by them, but I'd say 80% of T-Type owners who have tried them had nothing but trouble.
Steve Simmons

I put Grose Jets in my MGA many years ago. Besides the rare occasion when fuel came out the overflow because of some dirt in the jet (a couple times in 25 years), they've worked fine. I don't know if there has been a change in quality of manufacture that is causing some problems.

I was warned away from using them in the racing midget-- some folks had some bad experiences in a racing environment, but I'm not sure exactly what happened.

I think the Viton tipped needles have probably made the Grose jets unnecessary for what they were trying to achieve.
David Littlefield

Grose jets require, best I can figure, perfect tolerances at manufacture, then they work just fine. But a little bit off and they don't. Seems like maybe the new owners haven't caught on. I have a pair I put in in '68 or so, they have run perfectly ever since. But even then they were a love them or hate them proposition.

Seems ashamed to throw them away, though. I'll pay postage if you'd care tp want to donate them to my collection of cool things that almost work. Like my toilet paper oil filters.
kylemorley

Yep, Same here. Have had Grose Jets in for over 30 years and they still function perfectly. Guess, we need to add the word "new" to threads like this.
Bruce TD4139 Cunha

I think you guys have pretty much solved the problem. The original Gross Jets were made with closer tolerances compared to the new ones and more than likely the reason the older ones are holding up. Seems to be a trend that is following other products around these days. New owners trying to capitalize on a products past reputation and producing inferior replacements. It's a shame, but that seems to be the trend. Ever since the stores started stocking their shelves with Oriental products, everything went to Hell in a hand basket. JMHO. PJ
Paul161

No, it wasn't when the stores started stocking inferior import parts.

It was when WE started buying them.
kylemorley

I've been through several sets of Gross jets with little long term success. However, just a few weeks ago, I had rough running, and discovered the front float bowl empty. I checked the jet, and before putting things back together, I exercised the float lever only to discover it was the lever that was sticking. Not all the time, but after numerous flicking the lever up and down, on occasion it would stick. The little ears with the holes for the pin must be perfectly parallel, or there's a chance they will catch the sides of their mounting point and stick. More likely up than down, but stick none the less. Makes me wonder how many hits the Gross Jets have taken, when the culprit may have been the float lever ears. Just a thought.
L Karpman

The original Grosse Jets were created a few miles from here. The quality was excellent. It soon became a very profitable venture. As happens so often, he couldn't pass up the big offer that was made. At first the second generation was of decent quality. Too bad it couldn't stay that way. Bud
Bud Krueger

By the way, the Grosjets I mentioned were bought from a Volvo dealer. Back in the '70's Volvo dealers sold them in Volvo-branded packaging, as a cure for leaking SUs. So Volvo apparently thought they were a legitimate product.
kylemorley

Then I guess we are out of luck. Who makes the regular Viton tipped SU float needles? Burlen? They cannot even make a diaphragm in a fuel pump work when you use their little brass washer replacements on, say, a TC.
It just will not work with their washers. The diaphragm gets stuck. It is a well known thing.

It would not surprise me that Moss knows all about the problems with the GroseJets and sells them anyway. I have never had a problem using them. Got them 1.5 years ago and they work just fine. I did use a q-tip apparatus on the end of a drill to polish the little tube thing where they go. I assume everyone does that, though, right?
N Tesla

Nickie - The only diaphragm spacers I have had a problem with, were quite a few years ago, when they dropped the brass spacers and went to a four lobe plastic unit. Those wore quite fast and the diaphragm would go off center causing the pump to become very erratic. The four lobe unit was replaced with a plastic figure 8 spacer, of which 5 were used and they worked very well, but for some reason, BFS dropped them and went back to the 11 brass spacers. I have only used the new ones from BFS a couple of times and never had a problem with them. Since I have several pounds of the old disks that I salvaged out of old, junk fuel pumps I won't have need for the new ones for quite some time - maybe by then they will have come up with something else new - seems like nobody can resist reinventing the wheel. Cheers - Dave
DW DuBois

I just got a set of Viton tipped float valves from Moss and for now, their working fine. I put a set in the 72 B 5 or 6 years ago and they were fine when I sold the car last Summer, I guess their still in the carbs, the new owner hasn't said anything. So, I have high hopes that these new ones will last. PJ
Paul161

Yes, the spacer problem was a few years back. They never acknowledged it, just finally changed it. I never managed to loose any of the brass spacers, my point being they seem inept. My real point was about polishing (or at least a superior cleaning) where the float needle slides up and down. (along with everything else in there)

All the people who say the old grosejets are good and the new no good are basing it on that the old ones wave been working all these years, and people who have been trying new ones have a high failure rate. More likely many of the people trying new ones are not cleaning out the nearly invisible build up of varnish, etc. in the little tube. And, the people with the ones made years ago properly cleaned everything prior to install.

I like experiments, and that is why I bought some of the inferior new ones to try. First I polished the tubes, and they work just fine. Likely the ethanol adulterated gasoline will not cause a varnish buildup, so if the grosejets have been sensitive to a buildup...
N Tesla

This thread was discussed between 28/09/2015 and 05/10/2015

MG TD TF 1500 index

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