WTB 510 header

[73Wagon]

Looking for a 510 header in B.C. in useable or restorable condition. Thanks, Mark.

[datzenmike]

Unless you lost yours or have a cam and side drafts, keep the cast iron header on your L16. They will support up to 150 HP before a header might improve the flow. Headers have a shelf life they don't last and rust out, they never fit perfectly, flange gaskets often leak, they radiate more under hood heat, they make more sound and good luck finding that advertised 5 hp increase.



Only advantage of a header is they are lighter.

Don't throw away your old manifold so you can change it back.

[cartel]

I agree.
if u bring more air in. more air out. otherwise it's for sound only and probably loses torque.
now with a pair of 44s and a cam and large ports. it's a necessity
I have prob one extra but overseas auto might have new.
depends if u need short or long

[iceD]

Is there one cast iron exhaust manifold that is better than the rest? I heard there is.

ice D

[datzenmike]

There were two castings that were different from each other with one being more desirable I think.



The one on the left separates the 1 & 4 from the 2 & 3. Firing order is 1342 (or 3421) so this neatly separates adjacent firing cylinders as much as possible and with the two pipes joining together on the down pipe, as long as possible.

The manifold on the right makes no attempt to keep this separation. One and two, and three and four, fire in sequence and all dump into the same common internal pipe that separates only at the outlet. I think these were used on later L18 engines? and definitely easier and cheaper to cast.

[73Wagon]

Was there ever a cast iron exhaust manifold that did not have the dimples/intrusions on #2&3 runners at the head? I cant find the picture but I believe I saw one on ratsun "Duncan's Oz Goon" project. Is there a holy grail Australia /Japan market exhaust manifold? Or the exhaust manifold from a diesel L20B? Thanks for your input on the subject.

[datzenmike]

This indent?



Doesn't seem in impact the flow much.

This one. Never seen the likes of it before. Oz maybe?

[datzenmike]

....aaaand it was imported from Australia.

[yenpit]

Is there one cast iron exhaust manifold that is better than the rest? I heard there is.

ice D

From what I have found, here in the USA, the 68-73 510 had at least three different exhaust manifolds over the years. One has air injection ports at the top of each primary = 4 ports. These are fine & you can simply plug the threaded ports with an allen hex plug (bolts work, but look stupid!). There are at least two WITHOUT the air injection ports. One has a hole cast between the two lower runners, right above the lower flange. The other does NOT have the cast hole, thus is the closest thing to a tubular header = 4 to 2 with a dual (2) downpipe. I believe this last one is what has been called "the best" USA spec cast iron manifold. To me, the only time that last detail (no hole) would be imperative, is on a built to the hilt engine where you are looking for every detail to gain that last HP! But that is where a properly tuned long tube header should be used (I think Troy Ermish is the only guy making a proper long tube header these days). I think anything LESS THAN a built to the hilt engine would utilize a factory cast iron exhaust manifold just fine. I also believe that the current production "shorty header" is a waste of mulla, cuz it is NOT a tuned long tube header! At that point, I agree it only saves weight & creates more noise & can leak causing much frustration!

[datzenmike]

I have the discrete 4 into 2 and it has welded up air injection holes.

Not mine....



From Oz. Note the notch missing between 2 and 3. Much later 810 L20B. Has cast in provisions for EGR tubes or perhaps an AIS (air injection system) like the 720 Z series engines.

[yenpit]

Found my list! I do mostly 510 parts, but only ASSUME these are all USA spec............one or more could be JDM spec off the imported engines in the 1980's.........??

N22 casting no air injection ports, no cast hole between runners, with cast fins for cooling

N23 casting no air injection ports, with cast hole, with cooling fins

N26 casting with air injection ports, no cast hole, no cooling fins

U60 casting (521 L16) no air injection ports, WITH EGR, with cast hole, with cooling fins

[datzenmike]

Air injection holes can be filled or left. Casting numbers are superfluous. Nothing matters as long as 4 into 2 like the one on the left. This isn't a numbers matching Hemi Cuda.

[yenpit]

Air injection holes can be filled or left. Casting numbers are superfluous. Nothing matters as long as 4 into 2 like the one on the left. This isn't a numbers matching Hemi Cuda.

Oh come on Mike! People can take the casting # along with my notes & decide which one they want to look for I realize that there are circumstances where a Datsun casting # does not nail down details ie the A87 cylinder head & all its variants, but generally, a casting # does identify a component & details like this! The reason I make notes like this, is so I can glance at the casting # & know exactly which one it is. I sell quite a few of these, cuz I too am NOT a believer in those crappy "shorty" headers on the market today! A long tube header is the only way to go, if looking for those few HP's on a built engine!

Mike, do you have theory on why one version would have the internal casting hole & another does not? Exhaust pulses perhaps? I am aware of the difference, but not the engineering theory!

[yenpit]

PS I do agree with you on the true double runner design (your pic on left)............I'm gonna look at my casting # list, the manifolds I actually have on the shelf & if any are like the one on the right...........

[datzenmike]

$$$ the one on the right is likely cheaper to cast. It's always the money. For regular driving anything will do but I think it beneficial to keep the adjacent firing cylinders as far from each other as possible. Just like any header.



The L20B exhausts are 4 into 1 big plenum. I put an L16 manifold on my L20B. The down pipe is actually from a 240sx but with a custom made flange. I had to slit the pipes and crush together to get it to 1.5" to fit the flange. Lots of test fitting and tacking then the final weld.







It's over 30" from valve to where they join. My home made long tube. The KA uses basically the same dimension transmission as my 71B so of course the dual pipes bends perfectly around everything.



Took it off later to install a wide band. The manifold was off because at the same time I put my R1 carbs on.