A14 manifolds

[Nadodave]

I am reassembling an A14 engine.  I was shocked to see that the intake and exhaust seem to share a plenum.  Am I missing a part?  How can that work?

[pdp8]

There is a corrugated metal plate separating the intake and exhaust gasses, so they don't quite share.

The hope is the exhaust warms the intake and improves atomization and vaporization of the fuel/air mix, it also lowers the volumetric efficiency of the engine somewhat, so you get better mileage and worse power.

If you don't have that plate, then yes, you are missing a part.

Edited August 16, 2023 by pdp8

[datzenmike]

There is a bi-metallic spring loaded gate that opens when cold but closes exhaust off to prevent over heating once warmed up. The trouble is they always rust from the heat and unless maintained to make sure it is loose and functional it will seize in any random position. L4 engines use coolant pipped through the intake to warm it. The '75-'77 L20B tried the co joined intake and exhaust but reverted back to the previous coolant passages for '78-'80. I think the co joined manifolds was a bad idea in the long run.

[Nadodave]

Thank you both.  Now I need to find the three top parts in the drawing.  Appreciate the insight!

[datzenmike]

14095-U6700 is the corrugated plate and as soon as I saw it, (U6700) is always something to do with L20B engines so I did a search for all vehicles using this number and.... All '75-'77 L20Bs used in the 610/710/620/S10 200sx, A10 HL510 and all B-210s after '74. So lots out there.

 

Gasket is 14097-09500. Don't know if Nissan still has them. They would be included in the manifold set but 'spensive just for that. You can buy exhaust gasket 'paper' has metal in it and just cut your own with tin snips.

[pdp8]

One could make a usable replacement with just a flat plate of steel or stainless .062"-.125" thick and it would work.

That said, I could be convinced to sell mine since I've gone to a header and separate intake manifold.

[datzenmike]

It may be a nickel alloy to withstand the heat and resist rusting. At one time they were $58 at the dealer. If it was just stamped steel it would be $5. Yes it would work, don't know if it would last in the long run.

[pdp8]

12 hours ago, datzenmike said:

It may be a nickel alloy to withstand the heat and resist rusting. At one time they were $58 at the dealer. If it was just stamped steel it would be $5. Yes it would work, don't know if it would last in the long run.

Well, plain steel wouldn't last *as* long, but would still be fine for years.  After all, headers are usually just mild steel that's thinner than that plate would be.

Obviously having the right part would be preferable.

[Nadodave]

Awesome!  Thanks for the help.  I am sure I can fab a steel plate and can probably find appropriate gasket material.  That said, I am curious about the header and separate intake setup mentioned by Pdp8.  Is there a still source for those items?  And, I assume the stock carb i have needs to be rebuilt, and I have never had a lot of luck doing that.  A professional rebuild might cost as much as a new (and probably better) carb.  Suggestions?

 

Thanks again