Author Topic: Smog check valves  (Read 620 times)

Offline Gbailey1018

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Smog check valves
« on: May 19, 2022, 12:33:04 AM »
My 1968 V8 FB had the thermactor system originally installed.  When I inherited the car, one of the check valves was missing so I removed the entire system.  Now I'm ready to reinstall - I still have all original components, including all of the hoses (which were in really good shape), pump, cannister and smog tubes that screw into both sides of the engine block.  So I'd like to get check valves to screw onto the tubes that are as close to original as possible.

The blue valve on the left was on the car and was metal gray when I got it - I painted it blue since then.  The middle one I found on eBay and the one on the right is from NPD.  What is noteworthy is that the mechanism inside each of the two repro valves is different.  The eBay one has a spring holding what appears to be a simple plate in place - I'm assuming it moves and opens the valve only where there is enough fresh air pressure coming from the smog pump.  However, the NPD version has no spring and the plate inside doesn't move - it is simply held in place with a screw and has holes in it.  This appears to be similar to the blue one, but the blue doesn't have any Fomoco marking so I'm not even sure it's original.

Can anyone shed any light as to which of these check valves (if any) would pass muster?  Do the two repro check valves work in the same way?  Or is one or both of them simply incorrect for my car?


Offline rockhouse66

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Re: Smog check valves
« Reply #1 on: May 19, 2022, 08:39:20 AM »
The middle one is correct.
Jim
'66 GT FB

Offline Gbailey1018

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Re: Smog check valves
« Reply #2 on: May 19, 2022, 07:19:12 PM »
Thank you.  Does the one on the right (sold by NPD as concours for 428s and engines that use two valves, as my 302 does) work the same as the middle?

https://www.npdlink.com/product/check-valve-emissions/107425?backurl=search%2Fproducts%3Fsearch_terms%3Dcheck%252Bvalve%26top_parent%3D200001%26year%3D1968&year=1968

Offline Bob Gaines

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Re: Smog check valves
« Reply #3 on: May 19, 2022, 07:37:21 PM »
Thank you.  Does the one on the right (sold by NPD as concours for 428s and engines that use two valves, as my 302 does) work the same as the middle?

https://www.npdlink.com/product/check-valve-emissions/107425?backurl=search%2Fproducts%3Fsearch_terms%3Dcheck%252Bvalve%26top_parent%3D200001%26year%3D1968&year=1968
I have seen them before. The repro has the same physical dimensions as the genuine . With that said it should work on the 302 the same as the 428 given the shared the same applications too. It would pass muster once painted in all concours class's except Thoroughbred which does not allow repro parts. The other class's do not deduct for no Ford trademark. With nothing written otherwise I would assume that they are meant to function as original.  They look the same but I can not give commentary on if they will function the same.
Bob Gaines,Shelby enthusiast, Shelby collector , Shelby concours judge SAAC,MCA,Mid America Shelby

Offline Gbailey1018

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Re: Smog check valves
« Reply #4 on: May 22, 2022, 04:36:00 AM »
Thanks, Bob.  Appreciate the feedback.  This smog project has been going on forever, so I'm grateful to finally be getting this back into the car.