Zed Head

Is it running bad rich or running bad lean? Bad lean would give you some intake popping and bucking. You might check the FPR vacuum reference hose for fuel. That is something that could go bad suddenly. Also, if you still have EGR might be worth checking that. Maybe a channel opened up in the EGR passage. And, of course, the old thrown rocker arm. Fairly common after an engine has been sitting. You can eyeball that under the valve cover.

Could you add some poorer pictures from farther away? Throw some more dirt and grime on also. Ha ha ha...

The print on the actual part says 0 - 5. But the eBay text does say 3 - 5. Who knows.

Mike replied to a Support request that I made. In case anyone else has concerns. Thanks Mike. Sorry to be a pain, but it's a big deal these days. There really are hackers out there, and many of them are pretty good at what they do. https://www.classiczcars.com/support/1485/

Think about plumbing.

The bike shops also sell the regulators. Can't find specs though, yet. Edit - Looks like they are three bar. (https://www.ebay.com/itm/222779941480) https://www.denniskirk.com/search/fuel+pressure+regulator.q https://www.amazon.com/Fuel-Pressure-Regulator-Davidson-1995-2001/dp/B07W7QM3SM

The other benefit of that first one is that it probably does not leak down when the pump is off. The shiny anodized aluminum adjustable FPR's all seem to leak down because they use a ball and seat for the valve. The holder that you linked for the Harleys seems to be a two exit port system like the 1978 and later regulators. Looks like it would probably plumb in nicely on a 78 or later factory fuel rail. It took my brain a while to figure out how they worked when I first saw that style. The valve is actually inside the FPR, probably the flat steel seat. https://www.denniskirk.com/v-twin-manufacturing/fuel-pressure-regulator-housing-63773.p1802126.prd/1802126.sku https://www.ebay.com/itm/111963132346

Have you measured the pressure coming out of the mechanical pump, between the pump and the carbs? Don't know if you mentioned it, this is page 11.

The first one looks very interesting because it's adjustable and has a vacuum reference port. Do you have some internet links or part numbers? I've found that many of the older parts that would be valuable for the Z's are not actually available anymore. I built a vacuum reference adjustable FPR for my engine but now you can't get the FPR that I started with. NLA.

Found a book. https://www.amazon.com/Carburettor-High-Performance-Manual-SpeedPro/dp/1787111687

I'll bet that SU's have problems with high performance cams due to the nature of how they work. One problem with cammy engines is that they tend to run poorly at the low RPM where they sound the coolest. Really, to smooth things out, idle PRM should be raised to give a more consistent intake vacuum. But then you lose the lope. That piston is probably jumping up and down with each intake pulse.

Once the pressure is set the gauge can come off. No real need for a permanent gauge.

These look decent. Holley has been collecting brands and rebuilding their reputation so quality is probably fair. A selection of psi ranges. You would want the second one, I think. https://www.summitracing.com/search/part-type/fuel-pressure-regulators/product-line/holley-fuel-pressure-regulators?SortBy=Default&SortOrder=Ascending

I wouldn't use it. A decent gauge, those hose clamps, and pieces of hose would cost over $25. It's universal because they can change the ad copy to fit any application. 140 psi. "adjusts oil flow"? "ideal weight"? Not good... Fuel Pressure Regulator Kit: Prevent stalling, flooding, and other drivability problems by making sure your carbs are getting the right amount of fuel pressure with MOJTBE products. Adjust Capacity: This Aluminum Fuel Pressure Regulator Kit is adjustable from 0 to 140 PSI maximum fuel pump capacity. Optimally adjusts oil flow to meet your car's fuel pressure requirements. Materials: Premium aluminum construction for ideal weight and superior durability. Package Includes: 1x Fuel Pressure Regulator, 2x Hoses, 1x Accessories. NOTE: Not Legal in the state of California & New York, Not complies with C.A.R.B. regulations, Not for sale in the states of CA and NY. No instruction or direction included in the package, Professional installation is highly recommended.

That's an odd one. Looks like it has a vacuum reference port, which a carburetor would not need. But a 10 psi gauge which is way lower than any EFI system. Post the link, can't even tell what brand it is. Looks like eBay.

It might also be that they were putting in the extra effort to perfect the installation. "Blueprinting" the u-joint and shaft with extra care.

You're agreeing?

It's hard to imagine that Nissan would have a had a fixture that aligns the companion flange or transmission shaft with the future center line of the propeller or drive shaft, so that a worker could choose the proper snap ring thickness, while measuring play. More likely that they had a set of go/no-go gauges and sorted the shaft yokes by the width between the ears and assigned them a snap-ring color. The area between the areas would have been cut with the center of the yoke as the reference point. I think that somebody rebuilt that u-joint in the past and just used the wrong color or was colorblind, or didn't care.

Looks like one of those conflicting instructions areas. They say "don't change anything" but if you do change them so that certain conditions are met. Kind of like wheel bearing instructions - rotational torque or axial play? You have a dilemma.

Putting the image on the front page where people will click it kind of creates a cycle. I guess that explains it. Once it's on top it stays on top. Just wondering what the purpose was. Random images would be more interesting. Something new every day.

Just realized that I've been looking at the same "popular image" for many many long time.

How about a picture of the impeller? The other side.

This does not appear to be the case. Never knew about that feature, never sent an email or shared anything, or posted anything associated with my CZCC screen name. Don't of any of the mainstream social media things. Maybe @Route66 could share how they got the referral link. Welcome to the forum Route66! How did you hear about it? Supply details...

Who knows... https://www.classiczcars.com/profile/45020-route66/

I wonder what else is getting sent out from "Zed Head" at CZCC.com. Weird. I'll check out this Route66 person. Bet there's a web link in the profile.