Intake and exhaust manis for 74 A87 head

[antiextreme]

Noob here slowly trying to figure my way around my Datsun.  '74 620 pickup with an L18, A87 head and currently smog intake and exhaust.  Want to clean things up so I just purchased this L16 intake on ebay with the hopes that it would fit my head, assuming I can find an L16 exhaust mani to match.  Am I on the right track? 

[datzenmike]

All four cylinder L series intakes will physically bolt to all L series heads... not that you would necessarily want to do this. Yes that intake will fit.

 

The L16 and your L18 exhaust manifolds are the same. Your L18 may have an ERG pipe on it but you can remove it an put a pipe plug in the threaded hole or just trim it and pinch the metal closed and weld it up. Not worth the time, money or bother to search out an earlier L16 exhaust manifold. Plus you already have thew L18 exhaust so why risk breaking a stud over this?

 

L18

 

L16

[Stoffregen Motorsports]

That's the A46 intake. The best one out there.

 

The earlier divide port exhaust manifolds make more torque, but either one should be fine.

[antiextreme]

The exhaust manifold that I removed had bolts that shared surface space for mounting the original  intake as well.  That is, one bolt into the head held a portion of both manifolds in place.  Also, my original L18 exhaust manifold had a setup on top (I think others have called it a "stove pipe") that evidently opened to warm the bottom of the original intake.  Can this manifold still be used in conjuntion with my new L16 intake?  That would be great, but I can't figure how it's possible? 

 

Also, what gaskets will I need to hunt down now?

 

Thanks for the help!

[datzenmike]

All L series four cylinder bottom bolts or studs hold both the intake and the exhaust. A special 'cone' washer is used to bridge across both flanges.

 

 

  Also, my original L18 exhaust manifold had a setup on top (I think others have called it a "stove pipe") that evidently opened to warm the bottom of the original intake.  Can this manifold still be used in conjuntion with my new L16 intake?  That would be great, but I can't figure how it's possible? 

 

 

This is not how the original L18 intake and exhaust worked. You had better post a picture of the exhaust as this sounds like a '75-'77 L20B set up. Bolted together, Like this?...

 

 

The engine size is stamped along the top of the block directly behind the dip stick handle... better check this.

 

 

 

The stove pipe is used to collect warmed air from the hot exhaust and direct it to the air filter snorkel by an insulated pipe. Inside the snorkle is a vacuum operated gate controlled by a temp sensing air bleed that controls the opening and closing to regulate the air temp at around 90 degrees. Supplying the engine with stable air temperature reduces emissions but most noticeably, it makes it run smoother and gives better economy and performance. You can run any intake you like as this has nothing to do with it. Keep your L18 exhaust and the stove pipe.

 

 

Others have mistaken the use of the stove pipe for the coolant flow in the intake runners. If you look at the head side of your intake below the two pair of ports, there is a small hole that receives warmed coolant from the head. This coolant travels up each runner underside and exits just below the front of the carburetor. You can see the outlet on your new L16 intake just above the JAPAN lettering. The coolant will warm the air when it's cold and actually draw away excess heat from the close by exhaust manifold on very hot summer days. It both warms and cools the intake air as needed.

 

 

[antiextreme]

That helps, but it sounds like I bought a motor that was totally cobbled together. I will try to get some pictures up, but I can tell you the following:

 

Block stamped L18

Head stamped A87

Intake stamped U74

 

I would like to replace the U74 intake for a manifold I bought on ebay that is stamped A46. I guess I still don't understand if it is possible to do this while maintaining the exhaust manifold that was mated to my U74 intake, or do I need to track down a different exhaust manifold to work with my new A46 intake?

[datzenmike]

If the intake and the exhaust are bolted together just as in the picture I posted then the manifolds are from a '75-'77 L20B.

 

You can use your new L16 intake but the exhaust manifold might have to change also.

 

I'll wait for pictures...

[antiextreme]

Well, it looks like I clearly have an L20b setup, correct?  If that's the case would I do just as well from a performance standpoint to just run the original L20b intake and exhaust?  I would disable/remove the smog equipment in an effort to make things simpler and clean it up a bit.  Or, should I try to track down an L16 exhaust manifold to match the L16 intake that I just picked up?  Either way, I plan on installing a Weber Redline K660 32/36 carb.

[datzenmike]

If you remove those studs and put that spacer plate back on with bolts to seal the exhaust shut..... will the new L16 intake fit above it???

 

If so, just keep it.

 

If not, there are two ways to go.

 

1/ That exhaust has a single down pipe so get the L20B exhaust manifold from a '78-'80 L20B. It is separate from the intake and will fit beneath that L16 intake and still still bolt to your down pipe.

 

2/  Get an L16 or L18 exhaust manifold that will also fit below the intake but, it has two openings for a down pipe.  You will need to have a two into one down pipe made up to fit it.