Datsun Roadster Forum-311s.org

Glad I have some pictures to be able to put the plumbing back in order. I've not seen another photos or information on this smog arrangement.

- Here is a trick question for you.. Are harden valve seats required for "today's fuels" to keep form trashing the rest of the motor ?
Any experience with that ??
Cam

I have had a few heads off an have never seen major issues with the bronze intake valve seats. I would not take an engine apart just to do the valve seats. Do them next time the head needs to come off for other things like valve guides and stuff.

Keith,
Thank you for the information! I was hoping that would be the case

As it is, I have the clutch mc and the brake mc to rebuild/ replaced, lines to flush, wheel cyls to deal with. $$

I think that maybe a Datsun 411 intake manifold for an automatic transmission.

My '70 project also has the mystery device. I am planning to de-smog when I put it back together, but I also wondered what it does. Just bolted to the manifold with 2 dangly wires...They had to re-machine the intake manifold to mount that gismo, and only in 1970. I have 6 other intake manifolds without that boss. A lot of trouble for something that looks like a "feel good" smog helper.

I wonder if anyone who has a 70 has gone so far totally stock that they actually keep all that smog system crap....at least for the car show....
Linda

Mike . I have a late ‘69 and a ‘70 SPLs. My intake had the ‘gulp valve’ which ‘prevents backfired’ between gear shifts, I was told.

I sent my intake and SUS to Ztherapy for a rebuilding and every thing return in beautiful condition - except he plugged the smog ports and eradicate the gulp valve.

They are mounted on the engine, but I ve yet to fire the car up due to prior commitments.

Call or email Ztherapy for help maybe

That last pic shows ...what looks like a anti backfire valve
With high vacuum the engine pulled fuel through enough to cause a bf plus burn it it opened a big vacuum leak until vacuum lessend

I am trying to post a picture of an old and "new" (1970) intake manifold side by side to show the new casting with the boss for the anti-backfire device. I am not sure how to post a picture. When I click insert image it does not allow me to navigate to the image. I know I have done this before, but age is catching up...something obvious I am sure.

GULP Valve and the treatment performed by ZTherapy on my nasty intake manifoldand SUs. *Minus the SMOG)

I had to dig around for the before and after photos. Hope these help

It looks like Z Therapy changed out your manifold to an early manifold. They didn't have smog stuff.

I thought that was rather odd too. I figured that they would have returned the correct manifold. Now I have to strip the air pump and other smog parts off.

Will it run correctly now ??

If you strip the smog stuff off and set the car up like a pre smog car, it will run better. That being said, if you want to retain it, you could push back and tell them that you want the original 1970 manifold.

I think I’ll give the no smog attempt a try since the other smog parts are not in good shape to begin with

I gave to figure which bits to remove and what ports/ hoses need to be plugged - that’s going to be pain