• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

To Grose or not to Grose

Share this page

M

Member 10617

Guest
Guest
Offline
I have in front of me two new Grose jets and two Viton needles and seats for my float bowls. I've just finished completely rebuilding my carburetors and am putting the finishing touches on them. Based on the Moss description of the Grose jets as "superior replacement for standard needle and seat," I was planning to replace my Viton needles and seats with the Grose jets. But I've read a number of reports that the new Grose jets are not as reliable as they used to be and can cause flooding problems.

Your advice: install the Grose jets or leave well enough alone and go with the standard needle and seat? (BTW- the needles and seats I have are almost new, so probably still in good shape.)
 
I've fitted Grose valves to my cars because I have had so much trouble with the viton ones. The other day my son tried two or three sets of viton on a Bentley he'd rebuilt and they all leaked, so we put a set in and it immediately stopped flooding, so I prefer them.

As a precaution you could give the balls a tap with a hammer to make sure they've a good seat.

Ash
 
My opinion, stick with the Viton needles. The Grose Jets are a solution for a problem that didn't really exist to begin with, and in my experience are more trouble-prone than either the originals or the Viton improved needles.

I have "fixed" several TRs by throwing away the Grose Jets, and reinstalling the original valves.
 
Randall,

Just what I suspected. I was in the process of installing the Grose jets but then decided that before proceeding I would search the internet and the BCF a bit to get "reviews." What I read about the "new" Grose jets didn't encourage me. So I have put my standard needles and seats (Viton tip) back in place.

Many thanks.

BTW: I have had trouble with flooding in my float chambers. I thought it might be the needles and seats. When I opened the float bowls up during the carb rebuild, I found that some PO had installed float levers entirely incorrectly. They were bent way too high. I have installed new levers and have adjusted them properly.
 
It is funny though - when you see this question pop up on occasion you typically get the same mixed response - as Ash notes, they've worked for him. But is the issue the valve design, or perhaps rust or some other bad player at work coming into the carburetors?
 
I had the opposite of the usual Grose Jet failure... one of my Grose Jets stuck closed when the car had sat for a couple of weeks. Took awhile to work out why I was only running on 2 cylinders but the ball had got itself glued in place. I still run the GJ and the problem has not recurred so I am more or less ambivalent about them.
 
I don't think it was a made up problem that led to the grose jet's invention. I used to heve recurring, irritating carb bowl overflow with the SU carbs on my daily driver Sprites with SU carbs many years ago, the needle design would bind and stick. You could tap the thing or take the float bowls off and blow WD40 in their or whatever, and it would come back again in an hour or days or weeks, but it would come back.

This was with cars with original equipment parts and less than 10 years old.

At the time the g-js were advertised as giving "immediate throttle response" which was BS, but after tiring of the above described problem I equipped my next several cars with grose jets, including having them on my daily driver TR4A in the 80s, and never once had any float bowl problems in many years of driving, so I am a believer in them.

I don't know as much about the viton tipped ones, I think a got a set with a carb rebuild kit and they worked as well, but I have less experience with them, so haven't really formed an opinion.
 
Since getting my car in 2009, it has had standard needles and seats with Viton tips and I have had no problem with them. The problem I did have, as explained above, was that the levers were misadjusted. (The same PO who misadjusted the levers also switched the pistons in the suction chambers!)

I am going to keep the standard needles and seats in the car and monitor their performance. If I run into problems, I'll switch to the Grose jets and see how they work.

As for rust or debris in my gas, all I can say is that the screens leading into the float chambers are in excellent condition, and whenever I check them they are clean. So I am ruling out debris at that location.
 
All I can say is that in some 35 years of owning a series of TR3/A, I've only had a handful of problems with the original float valves, and never with the Viton tipped ones.

Sure, there have been a few times the valve would leak, due to crud in the fuel (like the soft lines to the carbs shedding bits), but just wiping the needle clean with my fingers always got me home, and fixing the outside problem always solved the issue for many years.

And the all-metal ones do have to be replaced from time to time, they don't last forever. I've never seen a Viton-tipped one that wore out, though. The ones I drove to work today have to be at least 15 years old and still work fine.

Few years ago, a good friend loaned me his beautifully restored TR3A to drive at VTR in PA. Driving down the road in the rain, I suddenly smelled fuel. Pulled over and got out, I could see the slick spreading behind the car. Liquid fuel was still dripping out of the air cleaners. Fred was a believer in Grose Jets; but he had wisely kept the old jets as on-board spares. I installed the originals, and had no more problems during the event or during the ride back to VA. And if Fred ever felt inclined to go back to Grose jets, he never mentioned it.

I believe the main issue is that the Grose Jets do have a larger bore inside (at least the ones sold for H6 carbs have a larger bore than the stock H6 needle valves). That means that it takes less fuel pressure to overpower the float.

I'm sure your Sprite didn't use H6 carbs, perhaps that is the difference. I don't see how a H6 valve could stick, unless there was some really heavy duty gum built up in there, or gunk blocking the valve open, etc.
 
I don't believe I ever had an issue with the TR4A carbs, which were Stromberg 175CDs, even as orginally equipped, but I was so skittish about all the issues with the couple of Sprites I owned that I replaced the needle valves with Grose Jets shortly after I bought it.

My Sprites were from the mid sixties, they had SU HS2 carbs, I think the HS SUs had a different float bowl arrangement than the H series, I know my Healey 100 float bowl was different than the later Sprite bowls, maybe some were more prone to problems than others.
 
Another vote: Viton is your friend!
 
My comments echo Randall's and Geo's. Over the years I have used standard metal float valves, Viton tipped, and Grose Jets. The metal ones eventually form a ridge that won't seal, and I have had Grose Jets fail both stuck-closed, and stuck-open. I have never had issues with the Viton tipped needles so that is what I have in all our LBCs at this time.

On a U.K. board I frequent they occasionally discuss problems with the all metal. Some parts apparently have a tolerance stack up between the bore of the fixed sleeve/seat and the moving needle. Their solution is to simply drag the edge of a knife along the edges of the needle body to remove any burrs. This generally insures the needle will move freely up and down. With the all metal valves, there are occasional reports of minor leakage that they sometimes resolve by removing the valve parts and "lapping" the needle to the seat using toothpaste. I gave up on all metal float valves before reading about lapping so I have never tried it.
 
I've had about as much trouble with one as the other, thought the Grose were the way to go but when something happens on the side of the road the needle valves can be cleaned quickly and your back in business.

Marv
 
I went to Grose jets in 1992 and have never had a problem with those two.

They went out of production somewhere around 1995 and were unavailable for several years. When I went to a triple Z-S set-up around 2001 the first needle valve used in the 3rd carb was the "conventional" type that came with rebuild kits. It tended to stick open right from the start.

Bought a couple of the "rev 2" Grose jets - one for the 3rd carb & one for a spare. The first failed open the same day as installed - the large ball stuck in end of the retainer. Either the ball was slightly too small or the retainer end was swaged a bit too large. A slight rap could free the ball, but if I shook the jet the ball would again lodge in the retainer. That one got sent back.

The spare did not lodge when shaken, so it was installed. I've had no problem with that one.
 
I put in new Grose Jets in my 1958 TR3A in 1990. I have never had an issue with them. I never re-set them or even removed them in the 109,000 miles I have driven my TR since 1990.
 
If I were to have a problem on the road -- and I'm not sure what the indications would be -- I'll carry a new set of standard needle and seat, Viton tip, with me in my took kit. These needle/seats, or even the Grose jets, are so easy to remove, clean, replace, that I don't think it would be a great problem.

But, then, as I said. If the car started giving trouble, how would I know that the cause was this little component?

On the other hand, in my garage at home, I can easily check the needle/seat from time to time to make sure there is nothing causing it to stick or not close/open fully.
 
LexTR3 said:
If the car started giving trouble, how would I know that the cause was this little component?
Click to expand...

At first you may not know where/what it is. With the stuck closed valve you would have lack of power, stumbling & inability to accelerate, possibly backfiring through the carb, and bucking but the car might idle fair (not good). However, those same symptoms may apply to plugged fuel filters and/or a failing fuel pump.

A stuck open valve is much easier to figure out as the car may flood at idle and you will typically find fuel coming out of the bowl overflow.

In both cases I think you have to have had this happen to you at least once on the road before you know to look at the float valves as the possible source of the problem.
 
Doug,

I think you are right. But many thanks for the possible "symptoms." If I experience any of them, I'll put checking the valve on my check list.
 
Back
Top