SM needles for SU's

[Z06C5R]

Hey all, I'm new here... I've been over at Zcar for about a year, and thought I'd start posting here too, for a second opinion.

Anyhoo - I'm looking into procuring some SM needles for my '71, and I was wondering if they would be a worthwhile upgrade for my otherwise stock L24 (although I will probably upgrade my coil and plug wires at the same time)?

[zguitar71]

A lot of people go from Z car site to Z car site, I am one of them. I think I responded to your question on Zcar.com. I think the SM needles will not do any thing for the stock 2.4, they can make the mixture too rich too. I know a person with them on a 2.4 and he has not had any problems but I do not think he has gained much from them either.

[beandip]

Hey all, I'm new here... I've been over at Zcar for about a year, and thought I'd start posting here too, for a second opinion.

Anyhoo - I'm looking into procuring some SM needles for my '71, and I was wondering if they would be a worthwhile upgrade for my otherwise stock L24 (although I will probably upgrade my coil and plug wires at the same time)?

There has been this misinformation passed on for a long time about SM needles. DONT DO IT. Even with a built 280 , they are too rich and will cause engine damage in the long term. The excess fuel in the chambers will wash away and or delute the oil film and early piston wear will be the result. The excess gas will also delute the oil in the crank case and bearing dammage is the result. I have pages of documentation on this , actually Kim Blough from IDAHO Z CAR , has done extensive testing in this area . He has published the findings . As well as several others. I have a never used set I will sell cheep. Gary

[Z06C5R]

So even if I upgraded the coil and wires to try and burn the extra fuel, it'd still be too rich? I was also thinking of putting a lighter weight oil in the dampers to lean it out a little under acceleration...

[landmizzle]

Howdy,

I would highly recommend that if your engine is stock (viz. stock bore and stroke, stock cam, etc.) that you not use the SM needles. You will not benefit from them.
I use the SM needles and love them. However, my 240Z engine has been stroked out to 2.8 Liters and it has a mildly aggressive cam that really comes on strong at around 4000 RPM. In addition, the valves have been enlarged to the 280Z version and I've had some port work done on the head.
With those changes, the SM needles work great. In your case I would pass on them or wait to use them after you've done some modifications that will benefit from their use.


Best Regards,

Landmizzle '72 240Z