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Exhaust header/stock manifold issue

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Hey guys,


On my 78 510 L20B I have been swapping over to SU carbs,and while I did this I decided I wanted to use a header to fix the problems with the air injection pipes that were getting in the way of the SU intake. I bought a new shorty header from eBay,and when I finally got around to mounting it I see it is pointing toward the steering box a bit too much for my liking.Also I see the small size of the rest of the exhaust,and the large diameter of the header collector,and I am not sure I want to change the whole exhaust on a car I may be selling soon. The thought I am having is to maybe cut off the tubes in the way of the intake,but I am not sure it will fit with the intake. I would rather not cut,and weld up a perfectly good stock exhaust manifold just to find it dowsn't work too well. The beauty is if the stock manifold works with the SU's then it will bolt up real easy to the stock exhaust. Is the idea of using a stock manifold welded up a good idea? I am not looking for a high performance engine setup here,which I know doesn't sound right coming from a guy using SU's,but I am using them because of the simplicity of them. I guess I could also just use a different intake manifold,and the stock carb,or a Weber down-draught,but right now I have the SU's mounted,and I am pretty close to firing it up,but the exhaust is holding me up a bit.


Any help would be appreciated.




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Is your HEAD a round or squareport?

Your header? square or rount port?

I dont know when exactly they changed to a round port exhuast head but you need to ck as it mayb have a square port head on there and was swapped.


if you have a short tube header (like from Top End Performance)they fit most L motor series cars/trucks.

Ck the website but they need to be ceramic coated otherwise they rust badly.



I habe no experience with the later model 510s so I really dont know.


I just know the later year stock exhaust manifolds are a pain to get the lower intake exhaust bolts and I hate them.

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My head is a round port,and so is the header I bought(seller re-welded the header flange to match the round port head). I bough the header on eBay through Bill's Datsun which is in Oregon,and the header is nice,but it isn't really aiming in a direction that I like with regards to the steering box/pitman arm. I understand what you are talking about with the bolts on the bottom of the stock exhaust manifold,but I could deal with it if it makes my life easier,and cheaper than getting a whole new exhaust.




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So I pulled the header off,and the gasket got a bit screwed up in the process. I tried using the stock exhaust manifold,but it was hitting the heat shield,and also very close(read touching) the custom throttle cable I made up for the SU's. At this point I just want to go back to the stock manifold,intake,and carb,but use none of the emissions stuff. It looks like I need to make a plate to block off the EGR on the intake,or what ever that is on the outside of the intake that bolts on near the carb base. Could I just get a Weber down draught,and use my stock manifold with a block off for the EGR? Where is a good place to get a new Weber? Would anyone be interested in trading for these SU's?


What do I need to know about getting a new intake/exhaust manifold? I ask because the one I have came with the header,and I am not sure it needs to be special for that application versus the stock setup. The gasket that came with the header is a Nissan part,but I am not sure if I need the same one,or one for the stock setup if I go that way. I am very frustrated with this car,and I wish I had never bought it. Actually I wish I had never tried to modify it. What a pain in the ass.




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I feel for you Comfort! It is pretty hard to move the late 70's early 80's Datsun Seadans. I know you are prolly wishing you could go back in a time machine and, not buy it, and now buy that sweet ass green 510 in NH! I am not downing them mind you, an 81 510 is what got me to like Datsuns in the first place! They just seem less desireable to the datsum community.


I can't remember if the 78 has a L20, but if so, I think what a lot of guys do is get the l16 manifold which has no emissions crap on it at all. Then just a simple weber 32/36. I imagine you'd need the electric choke one. Redline sells them new, so a lot of folks go that way. I got mine on ebay for like $150 with an offenhauser intake and high boy adapter. Bolted it on and it worked great!


You could also get ahold of Member Roostmonkey. He had a totally rebuilt stock carb for the L16 he was looking to part with pretty cheap. But the downside is it would be manual choke.

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Cut the air pipes off and unbolt the tubes from the exhaust manifold. Buy pipe plugs and seal up the holes. These metric ones were $0.50






Problem........ solved.

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The exhaust manifold is all set with the tubes removed,and plugged off. The issue I have now is with the intake manifold where it has openings for the EGR I believe. I also need to figure out what to plug off if I use the stock carb,or get a Weber,and not worry about such things. I just want this damn car running which it was when I got it,but I HAD to go and use these SU's.


I would love to get that sweet 4-door in NH,and maybe I will,but I needto get this one going first so I can sell it.

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I bough the header on eBay through Bill's Datsun which is in Oregon


theres part of your problem Chris, Bills Datsun is a joke.


dont waste your money with that guy, your going to get far over charged for mediocre work. Theve built that reputation out here for good reason.

Edited by Skib
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That is info I should have looked for before I dropped a bundle on the header. I just want to use the stock manifold,and carb,or maybe a Weber now. does anyone make a plate to block off the EGR,or sghould I just do it with some sheet metal? Where do I run the PCV from the block? I don't even remember where it went in the stock setup,but I am sure I have the part somewhere.

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I just want this damn car running which it was when I got it,but I HAD to go and use these SU's.


If it was running where is the EGR valve and why is it missing? Just find it or another and bolt it on and disconnect it to disable it. The EGR manifold also has the PCV valve on it and you don't want to run without it.

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