Hey everyone,

This is my first post on this board. Great posts on SU's and carbs in general. I didn't find anything on this, so if I am posting a question that has already been answered in the archives, I am sorry.

I have a 3.1L build that presently has SU's with Grose-Jets on it. I will eventually go to triples or throttle bodies but for now, this is what I have. In anycase, check out the attachment. See how there are two vacuum ports, one blue and one green? The next two? I am curious as to what they were for? Any recommendation on how to plug them? Are the NPT or some BPT? If not, I imagine I'll need to just drill and tap the holes and then plug them?

Thanks,

Brett

'77 280Z

I don't have a clue what someone has added these for, this a new one on me. You can just take the intake to a welder and have the holes filled or as you said tap them and screw in plugs or a bolt. As for your Grose Jets I have been reading for years in every venue not to use Grose Jets . ZTherapy would be a place to ask about them. Gary

Hey Gary,

Thanks for the reply. I rebuilt the carbs several years back with a kit from ZTherapy. I could not remember for sure which needles they were (SM, GrossJet, whathaveyou) but I found a packet the other day that said Grose Jets on them. Interesting. I'll look into it.

As for those holes, that is actually a picture of a new old stock manifold over at www.oem-surplus.com. I had originally thought that a PO had just messed with my intake, but apparently not. I'll look into it and post back. I imagine I'll just tap and plug them.

Thanks!

Brett

I don't have a clue what someone has added these for, this a new one on me. You can just take the intake to a welder and have the holes filled or as you said tap them and screw in plugs or a bolt. As for your Grose Jets I have been reading for years in every venue not to use Grose Jets . ZTherapy would be a place to ask about them. Gary

I believe that is a 260Z manifold from a car equipped with the flat-top carbs. Legend has it they flow slightly better. I had a manifold, N36 I think, that has the same ports. They were blocked off with screws if I recall.

Here's a picture of what came on my mid-'73 mfg. date w/ flat tops (one of the few things remaining from her that rust did not eat).

Hi sIR,

The blue one goes to the vacuum advance on the DIZZY. However, I'm not sure on the green one.

Hope this helps.