Mark Maras

If the mixture screws are within 2 1/4 - 2 3/4 turns down it indicates the float levels are close if not spot on. Great news. Random question. What weight oil are you using in the carbs?

Plugs are looking good. I actually thought it might be running a bit rich. The SU chokes are a great way to check for a lean mixture. How many turns down are the mixture screws now?

The line is continuous but is much less defined where it passes over the rear wheel arch. Both sides were the same.

More info please. Stock cam? How well does it idle when the engine is cold with the choke on? Describe "perfect color" plugs or better yet, pics. Are the metering needles stock? My first guess is it's running rich at idle. That's assuming that as the humidity is rising, so is the temperature. If the plugs are a nice tan color like we used to try to attain in the good old days the mixture is likely rich. Plugs run nearly white with today's fuel. Assuming it's had a recent tune-up, including a valve adjustment, I'd put in a new set of BP6ES plugs, and lean the mixture adjustment nuts a half turn up and see if it improves.

I'm going to guess it's the brake master cylinder. Pull the rubber boot off the end of the master cylinder to see if there's brake fluid in the boot.

Soak the whole assembly in EvapoRust.

Scotch Bright is an excellent choice. You'll want to confirm the proper float setting in the new, to you, SUs.

I hope the "quick sand on the nozzles" means you'll be using something akin to 0000 steel wool, not sandpaper. A thin coat of lithium grease will keep them sliding. Keep in mind that the fuel level in the float bowls is the PRIMARY mixture adjustment. Ztherapy has an excellent DVD "Just SUs". You'll be an SU expert after watching it.

Take a good look at the brass baulk rings. The teeth, when new, are pointed and sharp. The 2nd gear synchro will show the most wear, 3rd gear synchro a bit less. If the 2nd gear synchro looks good the others should be fine, although I have encountered broken baulk rings that looked good except for the crack. I've refreshed a few different transmissions in the past. GM T10s, Ford top loaders, Toyotas, etc. These Datsun transmissions aren't difficult to refresh. A thorough cleaning, new synchros, seals, gaskets and bearings are my usual refresh. I also use a dowel to keep the parts in order. Keeping the parts in order and oriented properly in the cleaning process will save a lot of time and headaches later.

Any idea of the wire gauge? I'd make some using 9ga. galvanized smooth wire. It's avail. from any fence co. that installs chain-link fence.

I agree that looks about right but you won't know for sure until you measure the temperature of the coolant when it's hot.

I'd weld a big nut on it.

The extra support may prevent the root problem.

That's the direction I'd go. Perhaps two surface checks. One cold and one hot.

As I understand it, the problem is always in the center carb. and only when it's hot. It would be interesting to see how much hotter the center carb. base gets verses the outer ones. Is it possible the manifold (and carb. base) are warping due to the heat and or the manifold is transferring too much heat to the carb. base? Have others had this problem using Canon manifolds?

I like it. Will the grommets withstand the heat and oil?

Yes they do sound like a wounded seal, even the new ones.That's the best description yet.

I doubt the problem is in the carbs. Both carbs rarely go bad at the same time and the engine will run (or try to run) on one carb. I'd start with a fuel pump check. Fuel pressure and fuel volume need to be verified. The test is available in any Z repair manual and a gauge can be borrowed from a parts store. No fuel to the float bowl possibilities are; clogged banjo filters on the carbs, bad mechanical fuel pump, Loose eccentric that drives the mechanical fuel pump, plugged lines, it's possible you also have an elec. pump and filter back by the tank. If so both should be serviced, Rust, flotsam and jetsam in the tank blocking the line is common.

They look the same as on my early 71 (late 70 build date).

I don't have it in my 401Z stash. You might want to inform the local Datsun and Z clubs in the NW. Craig's list might be worth a shot too.

I've used several layers of paper towels soaked in Evapo-Rust, then layed the wet towels as flat as possible on the vertical? rusty surfaces and covered the towels with Saran Wrap. (does anyone use that term anymore?) I checked the progress and re-wet the towels using a spray bottle as needed.

Don Kirshner introduced pure bubble gum music with cartoon band members because the Monkees got uppity and wanted to play their own music. Thanks for nuthin' Don.

I agree. It looks custom made. The welds they look OK but not professional.

If the Nissan bushings aren't available, others have reported using Dorman part #38397. I believe it's a door hinge bushing for a Mopar.

My original roll bar had flanges that bolted to the shock tower tops and another set that bolted to the front of the fender wells. I had to drill those holes. I wish I remember the manufacturer but that was 45 years ago.