Grose Jet needle valves
 

I'm looking for a set of these to put in a Nikki carb. Does anyone know who sells them?

New needles and seats come with the JP Sorensen rebuild kit - available through most autoparts places.

Haven't seen them sold separately for a long while.

I have used Grose Jets in Webers but no idea on anyone who currently sells them for any other application. Good luck though they work great.

DD - Those are the ones I'm currently using but I'm looking for the Grose valves so I can run a fuel pump with a higher output than stock. These would prevent the carburetor from flooding and I wouldn't have to use a fuel pressure regulator.

D Walker - I've heard they work great too. I've found a few places that sell them for Stromberg, SU and Weber applications, but not the Nikki. I know Rotary Performance used to sell them back in the early 80's for the stock carburetor, but I'm not sure how the Nikki valve differed from the other varieties available. It would be great if I could find a pair.

I've contacted one of the vendors and asked if they could send me the contact information for their supplier for these valves. Maybe I'll be able to find them that way.

Now I'm curious; I always just thought of 'Grose jet' as meaining the main inlet; from the German word 'große'. 'Große jet' would be the large jeet.


Quick web search shows them to be ball-based valves... intriguing.

Try here:
D & G Valve Mfg Co Inc
8 Mount Vernon Street
Stoneham, MA 02180-4527 map
Boston, MA-NH Metro Area

Phone: (781) 438-1789

Let me know if you find these. I have been searching for them as well! I'd like to put some in my Nikki carb when I finish rebuilding it. I've always heard good things about the Grose jet valves. They aren't prone to sticking like your typical needle & seat valve. They also don't wear out since you don't have the needle sliding in and out of the seat all the time.

PLEASE post back here if you find a source for them! I'll continue looking as well.

Jamie

Thanks DD, but I tried that number and wasn't able to reach anyone. I'll keep trying, but from what I've read on other sites, it seems like others have had difficulty contacting that place also.

Will do, thanks.

Just an FYI guys... running a Grose jet is not going to allow you to run a higher fuel pressure with out a regulator. They were intended to extend the life of the needle/seat as the dual BB design constantly provides a new sealing surface to the seat. They are not a replacement for tuning/ setting float levels properly. That being said, it's nearly impossible to still find Grose jets for even Weber carbs, which they were originally intended for (among other "racing" carbs) so good luck finding anything for a Nikki.

Apparently the patents on these have expired... do we have any precision machinsts amongst our ranks that feels like making some?

Used to be the hot thing for Detroit muscle when they were new cars and I was in high school.

http://jimsgarage.wordpress.com/2006...the-grose-jet/

Mazda Motorsports used to carry them.

http://www.who-sells-it.com/cy/mazda...-fullsize.html


http://www.who-sells-it.com/cy/mazda...5/page-45.html

Hmm. That catalog is 14 years old now. Any chance that Mazda would have some of these laying around somewhere? How does one normally order these Mazda Motorsports parts?

They show them on this page too. Anybody have the ability to purchase stuff from Mazda Motorsports?

http://www.mazdamotorsports.com/Part.../gallery06.htm

I checked it out and they are No Longer Available. Use the normal needle & seat.

0000-06-7311* nla 8/04 $13.10
$9.35

If only I would've bought these 7 years ago. Oh well. LOL

Moss Motors apparently offers grose jets still for British cars. Not sure if they would work in a Nikki or not. Thoughts guys? It's so cheap I may just buy one and see if it fits in the nikki air horn or not.

http://www.mossmotors.com/Shop/Searc...WebCatalogID=0

I have some unused standard needles in my spares box, & a caliper & micrometer at home; maybe if we give them basic dimensions, they can give you a go/no go/maybe more easily?

Glen,

Do you have the needle and the threaded seat or just the needle? From what I've read the only really critical thing about these Grose jets is the length. So as long as the length is close, and the threads are right it should work. If we could figure out what the thread is maybe Moss motors could match it up?

I know that Sterling was offering Grose jets as an option for his Sterling carbs for a little while. He said his quantities were limited though. So there is some variant of these grose jets that would conceivably work in the Nikki. Just not sure where he was getting his at.

Jamie

off the top it might work, the SU needle and seat is pretty small, like the nikki. the SU's aren't metric though, so this might be the issue.

ive got a couple SU needle and seats i can look at, and i think a weber, but no nikki's...

I've got the whole assembly, Jamie; I bought an extra rebuild kit last time I was ordering so I have a couple NIB needle-seat assemblies as well as a bunch of used ones on-hand.

I'll dig them out of the box tonight & do a little reverse-engineering CAD work.

That's what I was thinking/hoping too. Thanks for offering to measure them DD

the SU H6 needle and seat (1958 Tr3A)

the brass part is about 13/16" long with 3/16" threads

the needle is about 12/16" long, the whole thing together is about 15/16"

the thread looks to be about an 8mm although i think its whitworth, and not metric or standard

somewhere i have some MGA ones...

Someone check what the thread and pitch on the Nikki needle and seat is. If it's M7 x 1.0 you may be in luck. Scroll to bottom of page.

http://www.citroen-sm.org/wiki/index...ace:John_Titus

Grose-Jet

These are a reproduction, specifically designed to replace the Weber 175 or Weber 200 float valve in the Weber DCNF carburetor, but will also fit Weber DDE DLE (Citroen DS) and other Weber carburetors that use an M7x1 threaded float valve.
Cost: $18 each
Shipping: $6.00 USA; $13.50 international (up to 18 jets) via USPS flat rate envelope

??? Not sure what we're supposed to be seeing here.....

maybe there is a stock weber needle and seat that is close to the nikki needle and seat, then you'd know what to order the gross jet for?

I did some checking on the needle seat that I had laying around in my garage. From my measuring I am inclined to say that it is M8 x 1.0 thread. Can anyone else confirm?

Jamie

OK, measurements are:

SEAT:
Threaded portion, not including the narrow top 'nipple' that the final screens sit on, is 7.52mm long.
Outside diameter of threads is 7.81mm, so M8.
Thread pitch is 1.00mm peak-peak; M8x1.0
Main body overall length including threaded portion and 'nipple' is 22.90mm
Main body length not counting threaded portion & nipple is 14.00mm from the land that touches the carb body to the outside face.
Main body OD is 10.28mm.
The aluminum crush washer that goes between the seat land and the carb is 0.46mm thick, uncrushed.
Seat main bore (where the needle body slides) is too small for me to measure directly via caliper; looks to be about 5.92mm by visual inference.
Seat main bore depth is 11.32mm from outside to the face that is drilled for the needle
Needle seat bore (where the rubber tip sits) appears to be 2.00mm


NEEDLE:
The needle itself is a bit harder to quantify, because 1) it has a compression spring inside it, and 2) the tapered rubber tip protrudes into the seat bore, but I can't directly measure how much (it's deep in the bore at that point) so the working length has to be inferred.

The three-piece needle, with spring uncompressed, from tip to tip, measures 17.25mm in length, and 5.37mm across the high-points.
Fully compressed, the needle is 15.70mm cap to tip. So, total spring travel is 1.55mm.

When inserted in the bore and seated but with spring uncompressed, the overall length of the assembly is 27.25mm, and the needle protrudes 4.54mm.
Adding the bore depth to the needle protrusion, that means the "working" length of the needle, cap to seating circle, is 15.86mm uncompressed, and 14.31mm fully compressed.

That total spring travel (1.55mm) is the finagle factor, because we don't know the amount of that travel that must be compressed in order to close the valve against fuel pressure. Does the spring have to be fully compressed to close the valve, or only partly compressed... or not compressed at all?

I don't know a good way to tell.

Thanks DD and Jamie for your hard work! Hopefully, we can find something that will match up. If I find anything, I'll post back.

That's a good question. I would think that whatever state the spring is in during the initial float adjustment would indicate what's needed to completely shut off the fuel flow. The workshop manual doesn't clearly say either way.

Measuring the compression of the spring while the float rests on it in the inverted 'spec' will be tricky; it's not easily reached for measurement in that position.

Might be able to do it optically. I'll experiment if I get a chance.

I suspect the spring is only minimally compressed to seal the valve; consider:

Stock fuel pressure: 3.7-4.7PSI
Seat needle bore diameter: 2mm
Area of a circle 2mm in diameter is Pi(r^2).
Radius(r) is 1mm or 0.03937 inches. Squared, that is 0.00155; multiplied by Pi, that's 0.00487 square inches.
Total fuel pressure exerted on the needle is only 0.018 to 0.022 lbs.

I don't have a scale accurate enough to determine the spring rate, but it's moderately stiff for it's size. It's not going to compress a great deal under that loading.