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MG MGB Technical - GROSE JETS

Hello All--------------
I know there are Grose jets for some of the SU carb's,
but does anyone know of a Grose jet for the HIF-44 and if so where to get one! Thanks-----------
Dale
Dale & Barb Mast

Grose jets aren't as good as they used to be and I've heard many unkind things said about them.
Mike MaGee

Call Joe Curto and get his opinion (joecurto.com). He manufatures a lot of the surrent SU parts and is more than an expert on what works. He hates the grose jets too. There are a lot of bad standard jets out there as well!
Jeff Schlemmer

Just last week I pulled a pair of near-new HIF4 Grosse Jets from a car that had only been sitting for a few months since a carb rebuild. The front valve was seized in the closed position, so when the fuel in the bowl was gone, the motor needed half choke to run. I'd seen this problem before so I checked the fuel pump output, then stuck a piece of fuel line over the carb inlet and blew into it while tapping on the carb body. The valve released, so I knew it had been stuck, so I pulled the bowl.
There was no "old gas" smell, and no sign of dried fuel residue in the front bowl or in the valve. I soaked it in fuel injector cleaner, and reinstalled in the carb. It released and sealed repeatedly with a couple pounds of regulated air pressure on the carb inlet, while working the valve with my finger. But then it stuck closed no less than a half dozen times when I reduced the pressure to about 1 psi. The float was working fine and never hung up. I pulled the valve out and checked it out using gravity fed kerosene. It stuck a couple more times, but only when oriented as installed in the carb. On its side, or inverted, all was fine. I pumped the pressure up to 15 to see what would happen, and it held with no leakage, and it released every time. The rear valve seemed ok, but I replaced both with new Viton valves to be safe. For the price, I would hope to assume that the balls are of the finest non-magnetic stainless,and as perfectly spherical as possible - beats me why or how it stuck, and I tossed them both out so I'll never know for sure.
Mark

I installed Grose jets in my newly rebuilt HIF's to solve a fuel leaking through the vent problem. I tried two different SU needles, still leaked. I put in the Grose jets and the problem was solved. That was two years ago and still running well.
GM Chohaney

Mark,

Where does one get the viton tipped valves?
Paul Hanley

Paul,
I got mine from Moss in 2003.The part number used to be 111-6151 which was a 61-68 Jag E-Type number.You might want to get a hold of Moss to see if 371-055,which is the number listed now for the Jag, has a neoprene tip(viton).Let us know what you find out.
Tony
Tony Shoviak

Well, a few years back I converted 3 sets of SU to the Gross kind, and installed a set in a newly purchased set of 1 3/4. They leak and I cannot for the life of me understand the legions of high praise I've seen over and over for years. I'm with Curto and Mike above. The stockers are now back in all 4 and have functioned without clitch or leak #1. Vem
vem myers

Vem,
I think it may well be WHEN you bought your Grose jets or when they were made.

The set I have on my HS-4s I bought back in the late 1980s! They continue to work fine, in spite of other legions of opinion to the contrary. Why? Darned if I know, but my guess is that somewhere along the line the product has changed in some significant way.

There are many possibilities, everything from ownership decisions by new and different owners of the rights to the design, differing metalurgy of the components if bean counter or supplier choices were made which scrapped the original sources, or possibly, just poor workmanship (not much of an excuse today when CNC work in 2nd, 3rd, and even 4th world countries CAN be extremely good and economical). Given the just about equal numbers of happy and unhappy users, I do have to wonder if quality differences over time aren't the culprit.

If you or someone else can find a reliable source for the viton tipped needle and seat assemblies for these carbs, I think you would be doing everyone a great service by giving them a resource without exceptions and controversy.
Bob Muenchausen

I have to agree with Bob's assesment. I have gross jets in both our TD and MGB and have never had a bit of problems of any kind with them. On the other hand, I put a set in the HIF carbs in our daughter's 71 MGB and within a year had them stick in the same manner described by Mark. The only difference was about 10 years had elapsed from the time I purchased the ones for the TD and MGB. I have noted that the design of the Gross Jets for the HIF carbs was different than the ones used int he TD and the earlier MGBs with HS4 carbs. As a result of the experience with the Gross Jets in the HIF carbs have left me somewhat ambivilant towards them and I neither advocate using them or not useing them anymore. Dave
David DuBois

Paul,
I don't know if anyone still sells Vitons anymore. I have a pretty good collection of SU parts that goes back about 35 years, and was the lucky guy who, by sheer grace, was given a box filled with mostly unnumbered, but sealed British carb kits from the 50's to the late 70s. A fellow MGer that some listers might know - Walt Guenther (lots of A's and a couple of VA's) - gave it to me about 10 years ago when I borrowed an SU throttle reamer. It also contained at least 25 new shafts, bushes, a bottle of new split-screws, a full set of shaft reamers, at least a hundred labeled jets and enough washers to pack all the remaining HS4's on the planet... When I need something, I just pick thru the packages till I find what I need. Most of the kits either use the same viton tipped needle/seat, or one that will fill the bill with a bit of float adjustment. Like Bob, I also went many years on Grosse Jets without problems. But then again, my 57 Magnette sat for 14 years with dried gas in the bowls and fuel pump, but after cleaning the tank, it started right up and never leaked a drop. I drove that car almost every day for a couple years before I ever took the carbs apart.
mark

After many, many years I replaced a set of Grosse jets in my GT with a new set. Worked okay for several weeks and then one day I had a MAJOR fuel overflow problem with the HIF's and could have lost the car to fire. The Grosse jets would not seat themselves which was the root of the problem. I happened to be talking to John Twist and he stated that Grosse had been bought out by another company. It seems that all that remains is the original name with the quality of the source of manufacture not being up to that of the original manufacturer. I called Joe Curto and got a set of the viton-tipped needles and have been running them for the past year or so. I'll just stay with what I know works.
Bob

I've had the same experience as many of you. On the trip up to the UM Summer Party I would have some leakage from the front carb (and gas smell) at the 2500-3000 rpm range and the engine would stumble....get above or below that rpm range and the leaking would stop and the engine would run fine (thought I had a sticking float). Changed the front carb back to the stock needle and seat and the car ran great on the way home! I also heard John Twist and Eric Jones mention that the quality of the Grose jets had been in question for a few years. I have also had a running problem in my MGA where, upon start-up, I would have to tap the front carb bowl to get 'er to run. Guess I'll be taking the Grose jets out of it as well. Both pairs were purchased in the last 3 years so I'd agree it's a manufacturing problem....
Fritz

Ok Bob, I'll buy that, but it doesn't help my leaks. So the Grose were good once, not so good for a while and may or may not be reliable nowdays! Besides Curto, is there a retailer for the Viton tips? What is the product name of these gems, I need a gross of them ( heh hehe heeh). Vic
vem myers

This thread was discussed between 15/08/2005 and 27/08/2005

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