L20b manifold options

[frank88]

Hi all,

 

In order to fit a carb/carbs I'm going to need to get a new inlet and exhaust manifold as I have the California smog versions. I'd then like to clean up the bay.

 

As I'm very limited in what I can find in the UK, what exhaust manifolds would fit? Obviously the non smog l20 mani but if i cant find one are there others?

 

Are there exhaust flanges available to buy to then make your own? Or a cad file to get one made?

 

Thanks

[datzenmike]

 You have the L series engines?

 

Well here, the L20B exhausts were terrible with all four cylinders dumped into one outlet down pipe. Worse, the earlier ones with the U67 heads were bolted to the intake above it. The later W58 heads were separate. The U67 heads had square exhaust ports the W58 are round. Our earlier L16/18s did come with a 'cast iron header' 4 into 2 design that separates the cylinder firing order with 1 and 4 and 2and 3 paired. It needs a two joined to one down pipe back to the silencer. The earlier cast headers will bolt to the later L20B heads though even the round port heads.

 

L20B exhaust bolted to intake 4 into one...

 

Mklotz70 (a member here) did make the two pipe flange.

 

https://ratsun.net/topic/73044-rat-rod-header-flange/

 

 

[frank88]

Thanks Mike. So I could use an l16/18 cast iron manifold if I can find one? I think l16s and l18s came to the UK but l20s didn't. I have an l20 with w58 head but as said I have all the smog.

[datzenmike]

Yes an earlier L16 would work on a round port W58, just barely. Don't forget you will need to join two pipes together after the manifold.

 

You want to keep the block vent pipe and the PCV valve working but what I did was unbolt the EGR from the side of the intake and grind away the aluminum. A little JB Weld to fill in any holes and you have a 'smog free' intake that is larger than the L16 intakes that didn't have this.

 

This comes off

 

 

You lose the PCV valve. I tapped a hole for it and used one other as a vacuum source.

 

 

A quick glance you would never know that had once been equipped with an EGR.

 

 

 

 

[Rat-a-tat-Dat]

So, what about a 1980 720 KC 2WD with an L20B - equipped with torsion bar springs. The fitment here is a little more finicky,  especially with the L16 or L18 exhaust mani and collector. Any ideas regarding this scenario? Trying to shoehorn it in between requires some expereise. Looking for an easy solution, help!

[datzenmike]

The early 720 is almost exactly the same as the '78-'79 620. Both use the same engine and transmission and have torsion bars. The L16 exhaust will fit alright if you have a down pipe. The '73-'74 620 down pipe would work.