SU Linkage for L20B

[GoGoGo]

Think this has been talked about before but I couldn't find any clear answers by searching. I have a completely stock L16 automatic in my 1971 Datsun that is using stock linkage to a 32/36 Weber DGV. I recently picked up a L20B motor with 38mm SUs that the previous owner had connected to a cable linkage. I would rather set it up using the stock linkage to keep to original look of the car and/or concerns about having to drill the firewall for Lokar cable setup (which is what I would buy if I kept it cable). I purchased new Nissan 510 SSS linkage kit (99996-D1110) today and want to make sure that before I put the time to install it I won't have any major issues with it matching up to my stock linkage.

 

Any help would be greatly appreciated!

[datzenmike]

The SU linkage is farther in than the stock location. I'm told that the 510 linkage won't extend far enough. I don't know how true this is but my 710s telescope out.

This part...

 

The rod with the hook on the end (above) has to extend out slightly farther to connect to the SU intake below. Just to the left of the K14 casting.

 

[dgi]

Here's a couple of shots of my 510 with a L20b with 38mm SUs on a 220 manifold.  They may help you visualize how it needs to be setup up.

 

1. See where the J rod floats in the carrier at the firewall?  I eventually rotated that carrier about 30 degrees clockwise to lower the linkage.  As you see in the picture was too direct a connect from the throttle pivot rod making coming off closed throttle to be difficult.  
2. Also, I had to notch the throttle pivot support a bit in order to get enough rotation to reach full throttle .
3. And if I remember correctly, I had to heat up and twist the J rod a bit to have the system perfect.

 

 

[GoGoGo]

Thanks dgi! That is what I was starting to expect and since the linkage is already setup for cable it looks like I might be going down that route. Little more work in the beginning but it would ultimately have a more direct connection in the end. BTW is that an air cleaner box from a 1600 or a 240z? Did you have any issues with a filter being too wide?

[dr.feltersnatch]

i was running stock linkage to a set of 38mm su with no issues. i was running the k14 intake if that makes a difference.. i am now running the 46mm su and a cable system, only because they open backwards from the 38s. as far as the z car filter box it wont work. the carbs are farther apart on a z.

[dgi]

Thanks dgi! That is what I was starting to expect and since the linkage is already setup for cable it looks like I might be going down that route. Little more work in the beginning but it would ultimately have a more direct connection in the end. BTW is that an air cleaner box from a 1600 or a 240z? Did you have any issues with a filter being too wide?

 

I originally had a cable setup, but I didn't like the feel and wanted the stock linkage.  I should have also noted that the J rod did not come with the 1600 SU setup I sourced.  It was from another Datsun application and that is why I had to twist it a bit.

 

I did run the original linkage on a L16 with 220 manifold and no brake booster without any modifcation on an earlier car.

 

Yes, that is a stock air cleaner box from a 1600.  And you are correct.  There just wasn't room for it with the L20b and the power brake booster on my car.   Without the booster I could run the box barely, but I just didn't want to remove the booster.  It would also have been very difficult to run the cable setup I had with the box.

 

So, I went another way with air cleaners.  Here is how it looks now.

 

 

This pic shows you why I didn't use the stock air box.

 

No, the 240z air box doesn't work.  The carbs are much further apart.  Here is a poor shot of the spacing on the 1600 box.

 

Here is a set of 45mm carbs on a K14 manifold.  You can see the linkage is set up for a cable pull 

[GoGoGo]

That was very helpful! Based on the height difference of the L20B block I think the stock linkage may work "ok" but based on some other comments, people have had challenges with getting 100% full throttle and/or having to relocate the pivot point on the firewall. I was able to talk to the previous owner of the engine today and he forget to include part of the purchase (which is why I was trying to figure this all out!). Namely the bracket to hold the cable to the manifold, the actual throttle cable and even the gas pedal which he modified to attach to the cable system. So that is going in the mail to me tomorrow so I should have everything I need to run the carbs. I'll post some pics when I get everything so that maybe it will be helpful to someone else in the future. 

 

I like the 1600 air filter box as it's period correct and also allows me to hook up the valve cover vent at some point in the future. I'll have to look into getting one. Want to sell me yours?  B)

[dgi]

Based on the height difference of the L20B block I think the stock linkage may work "ok" but based on some other comments, people have had challenges with getting 100% full throttle and/or having to relocate the pivot point on the firewall. 

Reread my message above about the modifications to get 100% throttle.  Look at the last picture in that post on the right where the pedal linkage swivel is.  I've had to slightly modify that on both my 510s with SUs to get full throttle.  It just doesn't rotate enough to fully push the J rod linkage to full throttle on the SUs.  A few minutes with a file to notch the bracket to allow more rotation and you're done.

 

 

 

I like the 1600 air filter box as it's period correct and also allows me to hook up the valve cover vent at some point in the future. I'll have to look into getting one. Want to sell me yours? 

Wait till you get the parts you have coming in the mail to see how that mounts and pulls.  I've seen different setups (all cobbled together). Most would not work with the stock air box since they need to pull directly towards the box.  You would likely have to route the cable over or under the box and that might not work at all.  That's why I've always went with the linkage method shown above. (which is the stock appearance anyhow.)  

[GoGoGo]

I took some pics of the setup when I drove the car before buying the engine. Looks like the cable setup is routing fine (except for the chokes). I did find the bracket in a bunch of misc. parts. It's definitely custom made but looks like some thought was put into it. 

 

[Doctor510]

That is one of the better cable solutions I've seen.

[Jester]

 

 

:wub:  :wub:  :wub:  :wub:

[banzai510(hainz)]

cable might be better. as the pivot location is off and I had isses on a 510 with Mikinis. would alwasy pop out as it was a taller L20