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What the heck is this jet needle?

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jdubois

jdubois

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I finally got around to ordering new needles for the carbs in my '65 Spit, because I knew one was slightly bent and figured it was about time. Well, when I pulled the old needles out I noticed they're marked 007. The new ones I ordered, as is specified in the owner's manual, are marked 'AN'. So, I looked up the needle charts in the old "Tuning SU Carbs" book and plotted them to see what the difference was between the 7 and the AN. Well, I was pretty surprised at what I found. The 7 seems to be an EXTREMELY rich needle. What the heck? Why would somebody put such a rich needle in? Wonder if that's why my fuel mileage was never quite what I thought it should be.

See my chart below (it plots the jet opening, not the needle diameter, so higher value is richer). The orange line is the stock AN needle, the yellow one is the "rich" needle (H6) specified in the owner's manual, and the blue one is this 7 needle.

needles.gif
 
jdubois said:
What the heck? Why would somebody put such a rich needle in?
Click to expand...

Probably some PO looking for more performance that wasn't available with the stock needle.
 
I've often seen the 007 needle in a number of the salvage sets of SU's I've accumulated over the past 35+ years. I don't think that is the same 7 as the SU 7 needle is suppossed to be. There were a number of aftermarket rebuild kit providers and I think some of them had their own replacement needles. Some one else may be able to help here more. One way to get a ball park of what the 007 needle measures out to be is to take a machinist scale and mark off 1/8" increments using a fine lead pen from the mounting end. Then take a caliper and see what the measurements are. This could then be used to "place" it in the SU needle charts and see if it actually measures out like a #7. I agree that a #7 is way to rich for the street. #5's and #4's are about the richest we are using now. And, that is in a racing application.

HTH,
Mike Miller
 
Unless the engine is modified in other ways (cam, exhaust header), my guess would be that someone simply goofed.
 
Where the heck is Walhalla and isn't that in a song
 
Spridget64SC said:
I don't think that is the same 7 as the SU 7 needle is suppossed to be.
Click to expand...

Ok, I wondered about that. I guess I'll profile the old needles and see what they really are.
 
Poking around with Google, I found a place selling needles marked '007' and claiming they are for a Series 2 Ford Zephyr. I then went and looked up the Zephyr in the The Tuning SU Carbs book. It lists the needle for that car as a '7'. So, maybe I do have these ultra-rich 7 needles. Or maybe that place is confused as well.

Oh well, I guess I still don't know what I have until I actually measure them!
 
Walhalla is a little town in the NW corner of South Carolina. Just north of Clemson which is a university town. About 45 miles west of Greenville. Around 3,700 people. The company I worked with for 32 years transferred me down this way (from Charlotte, NC) back in 1992. Nice peaceful place in the foothills of the Applachian mountains. Got 17 acres of peace, quiet and a little more than a dozen LBCs sitting in or down by the barn. More scattered around NC and elsewhere in SC. The 48x36 barn is full of BMC and a few Rootes parts. The 12x18 former feed-storage building behind the house is affectionately called the Triumph shed. Been doing the LBC thing since 1973 when my addiction started due to purchasing 4 Bugeye Sprites as an engineering co-op student working my way through college.

There are a few other Walhalla's in the country, like in ND and MI. Probably wherever there are a concentration of Germans. Walhalla, SC was founded by German immigrants in the mid 1800's through the German Colonization Society based in Charleston, SC. We have Temperance towns near here too. These were towns formed which ban the sale or consumption of alcohol. The temperance part faded away long ago, but that's how West Union and South Union got their names. Kind of interesting though.

Been out to the Seattle area a few times and over to the Tri-Cities area (Richland, Pasco, Kennewick). Nice places. A lot different in geography, but each is pretty neat in their own way.

I'll look at the '007' needles this weekend and compare to a '7' just to see if there is a difference. It looks like there is to the naked eye.

Take care,
Mike Miller
 
Ok, here's the results of my profiling my 007 needle:

needles2.gif


Looks like it's at least <span style="font-style: italic">trying</span> to be an AN needle. It's a little bit richer, especially at idle, but it seems to track the AN reasonably well.

Hmm, perhaps I should profile these new AN needles I got in and see how good <span style="font-style: italic">they</span> are at matching the spec.
 
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