Grose Jets

[max71]

(Topic split from this thread)

Why's everyone bagging on my lovely grose jets? I used to deal with clogged/stuck jets all the time with this car until I went to these. Never had a sticking clogging problem since.

OK you naysayers. http://jimsgarage.wordpress.com/2006/09 ... grose-jet/ Please note the passage about original needles/seats:

The “needle” was shaped much like a rod with a cone on one end. The rod was usually not round. It had three or four flats so that the fuel had less resistance as it flowed past the cone end. The cone end came in contact with a seat that was angled much like the seat that an intake or exhaust valve seats against.

Over time the cone would develop a ring wear pattern where it constantly came in contact with the seat. They were usually both made of brass, but sometimes neoprene was used for the cone part to try to limit the wear pattern. Once the ring was worn into the seat, the valve never worked as it should and affected the carburetor’s performance.

BinGO. The whole problem right there. Never worried about it since I put these in. Been in the car over 20 years.

MGA guru agrees. http://mgaguru.com/mgtech/carbs/cb112.htm

Anyway the floats have been lowered a good 1/8 or slightly more. We'll see when I do a run.

[Jimmy]

I'll swap you for your lady friend's Aston.

Sadly, I suspect that she, too, would happily swap me for an Aston Martin.
And she already has one.

[max71]

Huh? Yes, I know she has one. She doesn't like it? I thought she was buying another one. DAMMIT Jimmy. How do you ever stay on topic in your articles? I have to read one of them. DO they start off about the car and end up about fuzz in your navel?

Oh wait. I just checked your sig page. You have one too?!

Can you please tell me the publications you write for? I want to apply. They must pay incredibly well.

[Steve Simmons]

So what you're saying is that because needle valves eventually wear and need to be replaced, that they are no good? The same could be said for 75% of the parts on your car. I simply can't agree with that, nor can I agree that needle valves aren't any good, as evidenced by their successful and popular use over the past 100 years.

I've said it before, if gross jets work for you then that's what you should use. I use needle valves on all my cars and they have always been extremely reliable, so that's what I use.

Just for clarity, neoprene is sometimes used on the tip of the needle to reduce wear.

[max71]

Needle/jets do wear. Grose jets do not.

[Jimmy]

Huh? Yes, I know she has one. She doesn't like it? I thought she was buying another one. DAMMIT Jimmy.

Well, she had one, liked it a lot, then traded it in on another one. Which she really likes a lot.
Either way, she would have to be a complete idiot not to want to trade me for an Aston Martin, regardless of year or model of the car. Especially since she's had me for almost 15 years now, and rarely keeps a car for more than three years.

[max71]

Huh? Yes, I know she has one. She doesn't like it? I thought she was buying another one. DAMMIT Jimmy.

Well, she had one, liked it a lot, then traded it in on another one. Which she really likes a lot.
Either way, she would have to be a complete idiot not to want to trade me for an Aston Martin, regardless of year or model of the car. Especially since she's had me for almost 15 years now, and rarely keeps a car for more than three years.

You're well past your expiration date. I think she could get some government financing for a guzzler trade in. She doesn't have to mention its a beer guzzler instead of a gas guzzler.

[Jimmy]

Oh, so now you don't want the Aston?

[max71]

I'll be magnanimous. Either your Aston or analyzer time with Malcolm. I'm open.

[malcolmr18zoy]

Hi Gary,
Two things. My gas analyser has stopped working, and grose jets do give trouble. I guess you've been lucky with yours, and maybe they're not as good as they used to be. I've experienced a lot more trouble with grose jets, and very little trouble with needle valves. The needle valves in my Jaguar are the old metal ones and when I rebuilt the carbs in 1992 I didn't replace them. They never leak and give no trouble,and they could be 50 years old. One of the troubles with grose jets is that they can't be disassembled to clean them. If you're happy with them that's OK. We all live according to our experiences.
Malcolm

[Jimmy]

That would leave the Aston option, then.
For once I'm glad it's not mine (aside from when insurance or registration is due).

[max71]

Malcolm,

There's not much to maintenance on the Grose jets. I guess you could soak them in cleaner if the balls got gunk on them.

I think I really soured on the needles when they went to the plastic ones which weren't as good. Then the rubber tip would wear that ring in it and not seal right.

Sorry about your analyzer. Or should I say I'm in mourning...

[Steve Simmons]

Oh gawd, plastic needles? That's asking for trouble, especially (I suspect) if they were older stock used with modern fuels. Had you been at a tech session with me a couple years ago and listened to all the veterans and professionals poo-pooing grose jets, you may have switched over! To be fair, there were some people there who liked grose jets. They were greatly outnumbered however. Still, if they work for you then stick with them. But don't discount them as your problem!

[max71]

The only problem I can imagine is if they are sticking and not letting gas through. If they are sticking I think I would see problems elsewhere, no?

So have they gone back to metal body needles?

[malcolmr18zoy]

One of the problems I have found with grose jets is over fuelling . I think, because the ball is heavier than the needle, the float can't make it seal as well under vibration. Also a ball is not likely to make as good a seal as a tapered valve.
I've never seen plastic needle valves, but some of the later ones had viton tips, or were spring loaded. I like the simple metal needles.
A sixteenth of an inch should make a difference to your high demand running. It's a matter of how close the fuel level is to the top of your jet that affects how much fuel can be pulled through it.
Malcolm