Hi all,

My son has a 72 240z that has Weber DGV carbs on it. I am trying to determin what jets would be right for the altitude we are at 5900 ft above sea level. It looks like it has 175/160 installed in it now and there is a package with 150/145 that came with the carbs when we bought them used. So, I'm guessing that just the main jets were changed?? I have heard from a couple sources that you wanted to go up 1 size for each 2000 feet in elevation. So, where does 3 sizes put me? It's a 2.4 l stock with an electronic ignition. Any help or advice would be great!

Thanks,

Mike

I'm afraid I can't help with the jet size question, but since you did ask for "any advice", I'll throw in my 2 cents. And I think most of the guys on here would agree. If you really want your Z to run like a Z, get rid of the Webers, and buy a set of ZTherapy SU's. Because the SU's work on engine vaccuum, I don't think elevation is an issue with them, but I don't know that for sure. There are plenty of guys on here in your area who would know better than me. Not a lot of mountains in Boston.

The SU's are pretty affordable (I think I paid around $700) and I imagine re-jetting the Webers probably isn't very expensive. But these cars were designed to run with SU carbs, and thats the best advice I can give. Sorry I can't help with the jet question.

I bought a set from ZTherapy for my 73, and every time I turn the key, I'm glad I did.

Hi Mike, I think we met a the ZCCC meeting the other week...

I had DGVs a few years ago and I'll paste from my notes the setup I used - fyi my house is at 6300 ft so quite similar to you.

- Primary main jet: 1.40 mm

- Secondary main jet: 1.35 mm

- Primary air corrector: 1.65 mm

- Secondary air corrector: 1.60 mm

- Primary idle jet: .55 mm

- Secondary idle jet: .50 mm

- Primary emulsion tube: F50

- Secondary emulsion tube: F6

- Pump jet: .50 mm

My setup ran just as well as SUs - not better, not worse. Given I've moved on to FI I'll try not fall into the old tastes great/less filling debate between SUs and DGVs. Suffice to say that when properly set up, both are good carbs and will easily meet the needs of a stock Z.

I'll guess that the current setup is running very rich. Given it's not much work to change the jets, I'd try the smaller set. They're still bigger than I ran, but see how it does.

Another FYI, I bought mine used as well, and when I tore them down for the rebuild found that the jets and air correctors were all mixed up. For example, on one carb the primaries and secondaries were interchanged. If you haven't already done so, it's worth going over them in detail to make sure they're assembled correctly.

Good luck!

PS. Don't forget the track day next Saturday the 19th at the State Patrol Track. Even if you're not going to drive, I think you and your son would enjoy it.

Just another example of the willingness of the people on here to help. Good questions generally yield good answers.