Failed CO emissions - all controls removed - where to start?

[Patcon]

You need a decent set of these

Then measure one of the valve lobes across the bottom width. Not from the peak to the round end but from one side to the other. That should be the base circle measurement

[thetwood]

3 minutes ago, Patcon said:

You need a decent set of these

Then measure one of the valve lobes across the bottom width. Not from the peak to the round end but from one side to the other. That should be the base circle measurement

Got it. Know I have those, just need to figure out where it put them in my garage... Thanks. Appreciate the help.

[siteunseen]

That fpr no matter where it is regulates the fuel pressure. My 77 had in on both sides return on bottom vacuum nipple on top. With mine and your straight shot fuel rails comes in the front closer to the radiator. Then the fpr takes that incoming fuel and regulates it (same psi) for the whole rail. It will take what you need and dump the excess through the return. That's the cool thing about those aluminum rails, they constantly flow fresh "cool fuel". No fuel overheating causing the hot restart problem a lot of folks experience.

So to answer your original question, the 78 fpr has an incoming fuel nipple that regulates the psi. And a vacuum nipple on top. Rockauto.com had one for $75 when  I did mine.

Edited September 12, 2019 by siteunseen

[Zed Head]

Here's more goodness from atlanticz's ancient page.  Looks like 33.3 mm is the typical Nissan base circle diameter.  You can measure that without removing anything except the valve cover.

http://www.atlanticz.ca/zclub/techtips/valvetrain/index.html

[Patcon]

1 hour ago, Zed Head said:

Here's more goodness from atlanticz's ancient page.  Looks like 33.3 mm is the typical Nissan base circle diameter.  You can measure that without removing anything except the valve cover.

http://www.atlanticz.ca/zclub/techtips/valvetrain/index.html

Ahhh pictures...much better! Thanks Zed

[thetwood]

4 hours ago, Zed Head said:

Here's more goodness from atlanticz's ancient page.  Looks like 33.3 mm is the typical Nissan base circle diameter.  You can measure that without removing anything except the valve cover.

http://www.atlanticz.ca/zclub/techtips/valvetrain/index.html

Measured cams. 33.3 mm short, 40.3 mm long. At least really close to that, converting my inches (long converted to 40.386 mm). Seems to be really close to stock if not stock. PO claims it was swapped out, but the lift doesn't seem to match up to any of the Schneider cams (at least those available now) which all have a much larger lift...

Raw numbers:

Short: 1.31" (33.274mm)

Long: 1.59" (40.386mm)

[Zed Head]

This just popped in to my head - some grinders use blanks to make their high performance cams.  So they could keep the stock base circle.  They only need to cut the base circle down if they regrind a factory cam.

Looks like Schneider does either.  http://schneidercams.com/dastsunL6_NA.aspx

Your measurements imply about a 7 mm lift, 0.28".  I think that Nissan rocker arms are either 1.5 or 1.6 ratio.  So you'd be at 0.42 to 0.45" valve lift.  Even with measurement error, that's not going to be a high lift cam.  Cam timing is important though and that might be where any performance improvements come from.

So it might be a Schneider cam, moving the RPM range for power, but it's not one of their super-duper cams, like the 300F.

[thetwood]

Thanks @Zed Head. Given what you're saying, it doesn't sound like the cam is of utmost concern at this point and I should concentrate on other areas. 

I'm going to order a Fuel Pressure Regulator, test some of the other things you guys have pointed me to and wait for the results of having the injectors flow tested.

[Captain Obvious]

That's a stock Nissan cam. Not a regrind. You might check and adjust the valves while you have the cover off, but other than that, move on.

Fix your fuel pressure and get your PCV routing correct.

[thetwood]

A bit of information coming in. I don't have the full results, but heard from the company I sent my fuel injectors to for cleaning/flow testing. Results were that the flow rate was approx. 190cc, which is pretty close to the 185cc of original. They should be on their way back to me tomorrow and I'll look at the full results. I'm assuming with this news, I should go ahead and reinstall vs purchasing new ones.

Also purchased a fuel regulator that I'll put on at the same time, in place of the aftermarket there now. With both back in place, I can start looking at why the fuel pressure is so low.

[EuroDat]

Well that is another possible cause scratched of the list. Eliminating  problems instead of assuming will get you there.

190cc will be close enough. More important is that they are ALL close to 190cc. Otherwise you can have lean and rich cylinders.

 

 

[siteunseen]

Anxious to see what the OE fuel pressure regulator does. My set up is very similar to your's except for that. I've only read bad on the adjustable ones like the one your car. Maybe this will get you where you can pass smog check?