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'73 240Z L28 Swap Questions


jsausley

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Hey guys. Hope to get some answers here for our race car engine...

 

We took our L24 out of our car and are putting an L28 in. It's a non-turbo from a 1978 model. It has been rebuilt. It was an EFI engine but we're changing over to SU carbs. Trying to figure out what we need to do with throttle linkage, fuel rail and fuel pump. We swapped to a P90 head and so we need to run a mechanical fuel pump, yes? We have the mechanical fuel pump from our L24. I don't remember what kind it is (I'm not at the shop now) but it is relatively new, definitely has been replaced by the OO before we bought the car. There should be no problem using the cam-driven mechanical fuel pump yes?

 

Throttle linkage/fuel rail: We have the standard N33 (I think is the number) intake with SU carbs, domed top (not flat tops). Is the fuel rail off of the L24 usable and is it compatible? It has some extra bits which appear to be smog or cold start or something. What's the best way to get rid of those? This is a race car engine so we are not concerned with any of that. Finally should we use the stock L24 fuel rail and throttle linkage?

 

I found this picture: http://forums.hybridz.org/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=8745

 

Is that equipment fabricated or is there place to buy the nice fuel rails and linkage? Also what kind of bushings are those (orange bushing between the SU carbs and the intake)? I don't have anything like that for our car and I noticed all of the SU pics on here have them.

 

Here's another pic of a great looking setup that I found on this website. The intake and linkage that we have is full of smog and other crap that we don't need. I'd love to clean it up to look something like this. Just looking for some options on where I might go to find this stuff.

 

http://i271.photobucket.com/albums/jj160/Dayz240z/31OCT2008014.jpg

 

Looking for a source for parts that we may need to get this thing operational.

 

Thanks so much for any help. I tried to search as best I can but I'm looking for some in depth info related to our build and I couldn't find anything.

Edited by jsausley
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The nicely polished set up you have there is a nearly stock affair. I believe the BALANCE TUBE (not fuel rail, that is a FI component)(on which the linkage mounts) is a European spec item, and has nearly no ports on it. (The balance tube is a universal component in all twin carb arrangements, it balances the vacuum somewhat in the two manifolds).

 

The one you actually have, if it looks like the second pic, can be capped off and used. There are lines to take hot coolant to your manifolds, perhaps to help vaporize the fuel? You don't need to link them up.

 

The orange items are fiber spacers used to insulate the carb bodies from the manifolds, to keep the carbs cooler. They are VERY desirable. I've seen SUs on a dozen different types of Brit cars and never seen a set up without them.

 

Oh, the 240 SUs will mount to any Z head. I don't know if you can use that head with that block.

 

You might want to read: http://datsunzgarage.com/engine/index.htm

Edited by BlueStag
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Thanks for the info. Where can I find those carb bushings, if you have any idea?

 

Which bushings do you mean?

 

The orange fiber spacers?

 

The Z stores should all have them, at a guess. I have never needed to buy one or even look for one.

 

Some people will put in two with longer studs, to help keep the carbs cooler.

 

Do a web search for "Datsun Z parts".

Edited by BlueStag
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I'm no expert but I'm pretty sure the P90 head does not have a spot for a mechanical fuel pump. You'll need an electric pump, and maybe a pressure regulator.

 

And if you used the original stock dished pistons in the rebuild of that 78 engine, you'll have a low compression ratio with the P90 head, which won't help your power output. Since you're racing, you can run high octane racing fuel and a high compression ratio.

 

No clue here on the carb parts.

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Thanks, I've seen that but the fuel pump hole facts didn't really register. It's still odd.

 

Comments about compression ratio still apply. Unless the engine was modified with flat top pistons, the CR will be low.

 

And the OP doesn't "need" to run a mechanical pump, but he can if he wants to. Maybe. Does the P90 cam shaft end have provision for the fuel pump drive cam? Might be easier to just go with electric.

 

Looks like fun.

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Thanks, I've seen that but the fuel pump hole facts didn't really register. It's still odd.

 

Comments about compression ratio still apply. Unless the engine was modified with flat top pistons, the CR will be low.

 

And the OP doesn't "need" to run a mechanical pump, but he can if he wants to. Maybe. Does the P90 cam shaft end have provision for the fuel pump drive cam? Might be easier to just go with electric.

 

Looks like fun.

 

Thanks from tech help from Motorsport Auto we did realized that about the CR and are using flat pistons. The cam we ordered is a racing cam from Comp and it can be used with the mechanical fuel pump. I found out where I can buy all of my carb parts from Z Therapy so we'll be doing that. Thanks for the info guys.

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Thanks from tech help from Motorsport Auto we did realized that about the CR and are using flat pistons. The cam we ordered is a racing cam from Comp and it can be used with the mechanical fuel pump. I found out where I can buy all of my carb parts from Z Therapy so we'll be doing that. Thanks for the info guys.

 

Ztherapy is the place to get the carbs rebuilt. Others do it very well, Zthearapy does it best.

 

If your carbs are sucking past the throttle shafts you will be miserable.

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