New World Datsuns...

Yep, vacuum gauge is steady. Next step is checking the intake with the boroscope, then removing the rear carb and seeing whats up. I'm also going to pull off the balance tube and check it.

DRIVEN wrote:I changed my mind. Carbs were a bad idea. Put the EFI back on.

Damn you, like button.

Fuck that! No EFI. I'm going to install the other set of 4 screw SUs I have and see if the issues return or get better. If that doesn't work, I may do a dual 32/36 setup with the SU adapters. Running out of time before Jethro Tull and Canby. May have to take the truck, dammit, noooooo! I want to drive the wagon!! Maybe I'll just yank the turbo motor out of the race car, get it running with the MoTech and put it in the wagon? As if I didn't have enough projects to do.

So the three screw carbs were the problem. They look recently rebuilt, not sure what exactly is wrong, but the bird noise appeared again after I swapped the 4 screw set on, then re-installed the 3 screw set because the linkages were better and I thought I was just doing something wrong. The biggest difference I saw was the throttle plates on the 3 screws seemed to be a little too small for the bore. Whereas the 4 screw, I had to tap them out of the bore, they fit that tightly.

I ended up rebuilding the 4 screw carbs with all the nicer linkage of the 3 screws, but I used the butterflies off the original 4 screw with the 3 screw oversized shafts. So now I have no leaks and tight shafts on 4 screws which are nice for float removal anyway, though I already cut off the mounting boss that's in the way of float lid removal on the 3 screws before finding out I still had a bird chirping noise out of the rear carb.

As luck would have it, its a good thing I did that. I barely even touched the head of the screw attaching the butterfly to the throttle shaft on the original 4 screw carb, and the head snapped off! So that was just waiting to break and get sucked into the engine. Got the car pretty well dialed in for idle now. It finally doesn't die. A/C is a problem. Drops rpm by about 300, so I'm going to use that auxiliary vacuum pump from the diesel Ford I had when I was fiddling with cam/vacuum issues on Ugly Betty, and instead I'll run it to the vacuum can on the throttle linkage to make an idle up. So when the AC clutch is engaged, the vacuum pump will start operating and suck the diaphragm to raise the idle by the appropriate amount!

Booyah! Still need to go test WOT. May have to get a slightly different needle profile, but either way, the damn 3 screws were the problem all along. I think it was the butterflies not being the correct size for the bore. I can't find anything else wrong with them.

Odd

Woohoo.

Hell Yea! Gotta love su's, always one of the first swaps on my list. Cant wait to see this thing at Canby.

Oh boy, it's getting down to the wire. The car is running pretty well, but too rich. The other needles are too lean. I'm almost to the point of grinding down the needle. In fact, I probably will tomorrow. However, the other option is putting the big lumpy cam back in. I'm almost just tempted to do that since it will flow more air and the needle will probably be perfect! Of course, the idle is going to be annoyed then. I'm going to change a shower valve and then think on it and investigate needle profiles. I have a pretty good idea of which one I need to make, so I'll be digging through needle tables to see if that profile already exists or if I just need to put the needle in the drill and start filing.

And the calipers are going wick wick wick pretty bad after some hard braking. Think they're sticking. Probably going to need to take them off and re grease the slides before I head out too.

My eyes hurt from looking at SU needle charts. I'm taking a shower and going to bed.

I remember Just Joel installed a Wide Band on his 510 wagon. He said he spend 2 months shaping a perfect needle for his application. At the end of it, his recommendation was to not install a wide band.

Lol, that has occurred to me as well. Sometimes less instrumentation is better.

Right now idle is pretty decent, 14. - 14.5 on a hot day, (80 degrees) mid cruising is 13:1 though. At night, it sits between 13.5-14:1, which isn't too bad. It's really close. At WOT it's 11.5:1

This profile is just a hair rich. Debating whether to fiddle more with needles or just accept no AC at idle and put the big cam back in to lean it out?

Maybe you need to figure out an AC idle up like EFI cars do. Ooo you could hook up a solenoid to the throttle shaft and have it rotate it like almost nothing just to raise your idle when AC is on...

I have the AC figured out. I have an aux vac pump from a 97 Ford Diesel or maybe it's an 07. Anyway, it works great, the only problem is once it reaches a pre-determined pressure it shuts off. And then when the pump is deactivated, the pressure still holds. So I have a Nissan vacuum switch I'm going to wire in conjunction so when the pump shuts off, it opens an air bleed. Thus, hit the ac, sends the signal to switch the valve and turn on the pump, which then actuates the vacuum can on the manifold and idles up. Probably not going to have it working before the trip, but I can just manually shut off the ac when it comes to a stop. All the rest will be highway anyway, so it won't matter.

BUT, here's something interesting. Remember when I had the small air filters and I couldn't figure out why I was having a limiter? I have 2" KN filters on now. I think there's a reason the z store sells 3" KN filter stacks for them. I just did a test run with the air filter off, and in the heat of the day, wouldn't you know it, the AF ratios are almost perfect. So I'm going to buy some Ramflow foam elements that should flow more and solve this little issue. Looks like a W03 needle works fine with this setup after all!

Cannabalized a 240 Z air filter plate for the air horns, which are smaller than the really expensive ones I just got, and some motorcycle UNI sock filters. It's going to work! Wish they would have sent new gaskets with the new air horns I could have used. Bah. Almost have the air filters set up. Should work nicely for top end. Or so I think. Going to eat some food, then do some testing. Then work on the 9 other things I have to do before tomorrow morning.

And find e-fans for Keith.

And none of the air filter socks worked with the air horns. Started doing some research, found you want about 1.5" from the air horn lip otherwise it sucks in the filter element. As found after I worked so hard to install air horns and then took for a test drive and nothing past 4500. Fuuuuuuuck. So I put the KN plates back on. Need taller filters, but not quite 3" Bah. Or I need to make a custom box with the air horns inside. That would be better.

Done for tonight, going to get up early and get some stuff done before heading that way.

Well, at least you got to ruin a perfectly good Z base to find that out.

Is it fixed yet?