Hitachi SU Carb Jet Alignment Tool DIY for Datsun Nissan 240z

[240260280z]

I am rebuilding carbs and did the dreaded "Loosen the 19mm jet lock nut" without realizing it was a bit of trial and error to realign: (Well the secret is to push the jet up into a lowered needle while slowly <s>turning</s> twisting the 19mm along its axis [like screwing on a bottle cap rather than wrenching. If you know about the "T" handled socket for turbo rebuilding then you know what I mean..nudge nudge wink wink say no more say no more... What's it like?]). So tonight, even though I aligned the jet by the above method, I decided I would try to find/make/invent a tool at the ACE hardware store.

Plan A

My first idea was to find a screw that would fit in the jet then turn the head using a file and electric drill. No luck finding anything smaller than 3mm (which happens to be the diameter of the needle securing hole in the piston). Well Plan A -1 was to turn brass rod on a lathe but I don't have one!

Plan B

Next I looked at rivets and found one that would do but there was still a little play in the jet as the shaft of the rivet was a little too small. Then I went and looked at the stock rod and a solution was found:

Plan C

The Parts:

As you can see, the stock hollow brass tubing is what I used. The sizes are 1/8" inch and 3/32".

The cost was very favourable as well.....well a bit more than a rivet or screw but hey ~$3 is mighty fine for a specialty tool. I might add that this is the only special tool I know of that is needed to easily rebuild SU carbs.

How Each Part Works:

The bigger 1/8" (3.18mm) tube fits snugly into the piston.

The smaller 3/32" (2.38mm) tube fits very well into the jet nozzle.

The smaller 3/32" tube also fits nicely into the 1/8" rod

So to make the tool, I cut an 8mm length of the 1/8" rod. Slid it on a 50mm length of the 3/32" rod then soldered them together.

Some sanding of the solder and a little off the 1/8" rod (3.18mm to 3.00mm) completed the job.

The completed tool below a jet nozzle.

Here is the tool in the piston.

Here is the jet fitted by the tool.

If you don'd have a clue what I am talking about then take apart an SU carb's jet assembly

Enjoy!

Edited August 5, 2011 by Blue

[5thhorsemann]

Neet widget, are you planning to sell them?

[Bruce Palmer]

We have a jet centering tool available for sale left over from the Scott days. Don't think we've sold two in ten years.

Anyway kudos for your inventiveness.

[240260280z]

I reviewed my design and I am about to make a mk-II version .

Horseman, PM me your address and I'll send you one.

Bruce, yeah I hear you. There are not a lot of geeks tearing up SU's these days.

[Bruce Palmer]

Prior to a total redesign wouldn't that be a MK-1 MOD-2?

[240260280z]

Total redesign This change rate is worse than Apple's iPhone versions .

Now off to ACE hardware. Stay tuned.

[240260280z]

Mark II is $0.43.

It should be better than Mk-I because it aligns the nozzle guide directly rather than aligning it through the nozzle. This reduces the error/slop that exists between the nozzle and the guide.

It consists of one 1/8"dia X 3/4" metal pin and one 1/4" dia X 23/32" long nylon spacer with 0.110" ID.

Just tap the pin part way into the nylon spacer and that is it.

Mk-II Parts: Steel Pin and Nylon Spacer

The nylon spacer fits in the jet nozzle guide.

The steel pin fits into the piston's needle hole.

All three parts aligned

Ace parts 44237-C (nylon spacer) and 58011-K (steel pin)

Now to finish a front differential mount to put Ron Tyler's design, complexity and cost to shame.

Edited August 5, 2011 by Blue

[Bruce Palmer]

Good grief man! $.043 each? I'm here to tell ya Ztherapy is ruined, I tell you, ruined!!

Sell every one the western world wants to buy and you'll maybe have lunch money. Such is normally the case with these niche market tools..... Oh, don't forget the ad budget...... nyuck nyuck

[240260280z]

Only folks on ClassicZCar.com can see these "Technical Articles" so you are ok for now

Off to ACE again for another project.

Hey, I'm the guy who made front bearing drifts from $2 cast iron pipe fittings.... I must have Russian blood in my veins.

Edited August 5, 2011 by Blue

[240260280z]