Carb Needle Position (Hitachi HJG46W)

[TimW]

Hi Peeps,

I'm in need of some help please guys. I've started to dabble and getting to know the car. I've seen a couple of posts about the needle collar should be level with bottom of the piston, not bottom of the groove, is that correct? Sorry if this has been asked before, I couldn't find pics of the grooved piston.

When tuning, the mixture nut seems to have little to no effect, could this be the effect of the needle which is currently set as below?

 

[Mr Tenno]

This any help? http://www.classiczcars.com/topic/44218-su-needle-installation-help/

 

[Sam_C]

Yes, the shoulder should be level with the bottom of the piston, not the bottom of the groove. i recently re-set mine with new needles and float chamber needle valves. I also checked and set the float level height and now it runs like a Swiss watch.

 

[TimW]

Good read, Thanks Tenno.

Thanks Sam, I'll lower the needles and check the float level. I think I'll take the carbs off and give them a check over, something ain't right somewhere!, Will post how I get on. Where did you get your needles from Sam?

 

[Sam_C]

Good read, Thanks Tenno.

Thanks Sam, I'll lower the needles and check the float level. I think I'll take the carbs off and give them a check over, something ain't right somewhere!, Will post how I get on. Where did you get your needles from Sam?

Got the needles plus 2x carb rebuild kits from Mike at MJP. I think they were SM needles which are SU rather than Hitachi. I just asked Mike for needles suitable for a standard engine and he advised. Ask him the same question rather than asking for SM needles in case I got that wrong! I got the rebuild kits so I could get the new needle valves. I believe that today's fuel doesn't agree with certain types of needle valve tips so I thought it might be a good idea to do it while the carbs were off the car. If you decide to do yours, just be aware that that the kit comes with two different length needle valve bodies and no instructions as to why! The longer body is for the front carb. The valves are easily swapped, just a small spring clip holds it in place. You will need two rebuild kits, one for each carb but they are not all that dear in the great scheme of things.

I also got some "proper" SU damper oil for the carb pistons from Burlen. It's probably just any old oil, but it comes in a nice SU branded bottle

Good luck, hope it improves things for you.

 

[Rob Gaskin]

Good read, Thanks Tenno.

.................. I think I'll take the carbs off and give them a check over....................

That's RIDDLER'S old car off the road for the summer then. :lol:

 

[TimW]

rofl Rob... Could be buddy, depends how quick I learn!.. Its been some time since I did any mechanics, but he who dares wins.. .. Anyways, I'm thinking your'e only up the road and my wife bakes really nice cookies..

The pic below tells the storey so far Rob.. Detailed around the battery area and throttle linkage so far.. running out of grip seal bags and labels.. haha..

Great stuff Sam, thanks.. I'll give Mike a call and get the kit and needles. The carbs are off now, so might as well go full hog. Think I'll get some of the Burlen oil for dampers as well, I like everything as it should be.

The float in carb one looks decidedly dodgy, bent to one side (pic attached). Good starting point I think. Trying to work out measurements/settings atm, will be posting again shortly I imagine..

 

[Sam_C]

Tim - this is a really useful read concerning the needle valves and float levels.

http://datsunzgarage.com/engine/

 

[TimW]

Thanks Sam.. Interesting, some good tips there.

I've spoken with Mike, he's sending me some SM needles and a rebuild kit to follow when in stock.

I've straightened the float and set to 15mm, once in place and the new needles installed I'll run the 23mm hose test suggested on the link. That should do it, but that 10mm Trick mentioned in the link looks interesting. Now I've seen it I've gotta try it. lol..

Just reading up on the different carbs atm, I've seen somewhere that on certain SU models the float setting on carb one is different to carb two, but have a feeling that's on 1970 carbs.

 

[uk66fastback]

How are the choke cables operating Tim? All well and good?

 

[TimW]

Not too brilliant Fastback.

You can't really see from the photo,it's the only one I have atm, but there seems to be two issues.

1. They seem too long. If placed in the valve cover clips the bend is too great after the clip and the are way above the bonnet line, thus forced down when the bonnet is closed. I have a feeling these may be the original cables for the 260 flat top carbs, thus may be different for the installed 240 carbs.

2. Where seated in the carbs (red arrow), they're literary loose, just the nut on the choke lever holding the cable in place, nothing holding the sleeve in place, no rubber bell houses etc.

The choke seemed ok, going off fully, but having the cables flopping in and out of the carb seat needs sorting I think.. Pretty sure there's come clips missing where the cable housing meets the carbs. ... Any clues Fastback?

 

[uk66fastback]

Tim, I can only go by my 240, where the choke cables go to each carb you should have a rubber bellow on the end of the cable, this slots in on the carb and then there is a small fixing on each that holds the metal part of the bellows in place on the carb. So the sheath is fixed and then the cable is free to move inside it and open/close the choke.

I'll find a pic in the morning - or take one if I can't find one ...

 

[TimW]

Lovely, thanks Fastback.. Yes, I thought something not right there. I've had a thought on the length of cables. Will check route through into the cabin, maybe I can pull them trough a little to shorten the length inside the engine bay. Not sure, but I'm really loving getting to know the Z's.. all good fun!..

 

[uk66fastback]

http://thumbsnap.com/IukuwLb3

I can't get Photobucket to work for some reason so here's a quick pic.

The choke cable - it's just ONE loooong cable (A & A) come through the bulkhead and go under a bracket on the orange air filter housing (on mine anyway), then the shorter one goes into the nearest carb into the hole (B) held by the nut (D), having first passed through the retaining fixing (C)

!!

Hope that makes sense. I'll get a pic of mine actually located correctly a bit later if you like ... (I took this shot of mine last summer)

 

[TimW]

Thanks Fastback.. I think we may have different carbs, mine are four screw. Your linkage makes more sense, I just have the cable loose in the carb casing (A in pic).

Where the nut is on the cable (B in 2nd pic) it looks like something is missing, maybe a bellow or something. Not sure, could be a hang up from the 260 carbs. Will do a bit more hunting around on the net. Can't imagine that would be factory spec.

 

[uk66fastback]

Tim, here's a pic of Woody's engine bay ... again, it's a 240. Shows how the cables fit. Like you though, he doesn't have the bellows at the end - they perish after time.

Click below and then double click on the next pic.



You need someone with a 260 to chime in really ...

 

[Rob Gaskin]

Tim, this is my '73 240Z setup.

 

[TimW]

Eureka..!

From the picture of Woody’s and Rob’s I think I’ve worked it out.

My choke cables are the same as Rob’s, except mine are missing the bellows. At a guess, the bellows were removed so as to fit the 240 4 screw carbs when they were installed.

The double clamp in Woody’s is what ‘I think’ I need. I’m guessing that there’s no need for the nut on my cables as the top part of the clamp ‘looks like’ it holds the cable sleeve in place and the lower holds the clamp to the carb body... which if correct means; Cut the cable sleeve to remove the nut ( can also shorten the length at the same time.. a double win.. ) and source the double clamp. Preferably the other way round, before I get the cable cutter oooouuut!...lol..

I’ve looked high and low for the clamps for most part today, no joy. I’ll call Mike at MJP.

SM needles have arrived, weekend ahead... Sweet!

Thanks Guys, much appreciated!..