Fixes for crappy L-series header fitment
Fixes for crappy L-series header fitment
Hey all, I'm in the process of fixing a bunch of mechanical gremlins while my engine is out of the car, my biggest concern is the header fitment.
The engine is a L20B, U67 (square port) head. The intake manifold is an alloy Lynx item with a 13mm thick flange. The exhaust manifold is an unknown brand 4-1 header with only about a 9 or 10mm thick flange and a pretty small contact area for the big washer to press on it.
Going back to stock manifolds is not an option, and I'm sick of bent/broken manifold studs and leaky manifolds.
What do you L series aficionados suggest as a fix to this problem? Should I attempt to file/sand the lower flange on my inlet manifold down to the same thickness as my exhaust manifold flange, or will that weaken it too much?
Or would it be better to modify my exhaust header somehow?
The engine is a L20B, U67 (square port) head. The intake manifold is an alloy Lynx item with a 13mm thick flange. The exhaust manifold is an unknown brand 4-1 header with only about a 9 or 10mm thick flange and a pretty small contact area for the big washer to press on it.
Going back to stock manifolds is not an option, and I'm sick of bent/broken manifold studs and leaky manifolds.
What do you L series aficionados suggest as a fix to this problem? Should I attempt to file/sand the lower flange on my inlet manifold down to the same thickness as my exhaust manifold flange, or will that weaken it too much?
Or would it be better to modify my exhaust header somehow?
The IDx 10 concept is based on the 510 in the same way that the urinating I was doing last night was based on a 30 yr old single-malt scotch.
-McWicked
-McWicked
Re: Fixes for crappy L-series header fitment
Weld some steel to the header flange to make it as thick as the intake. You may also be able to improve the contact area size at the same time.
Jim Graham
71 Plum Crazy Wagon
71 Plum Crazy Wagon
Re: Fixes for crappy L-series header fitment
what about tack welding some washers onto the exhaust header, then grinding off the washer material that would interfere with the intake mani fit... fir out the exhuast mount points instead of shaving the intake. someone chirp in if warpage of the flange plate would be an issue.
Merlin from Datsunhistory.com
"test mule? I don't need no stinkin' test mule... Bert Vorgon is my test mule"
"test mule? I don't need no stinkin' test mule... Bert Vorgon is my test mule"
Re: Fixes for crappy L-series header fitment
Sounds like you have a leaky header, so I don't see the improvement from a stock manifold. Do you have a picture of the header? If it is the common cheapy, you're way better off in every regard with a good stock cast manifold. More power, less noise, fits like stock.broke wrote:The exhaust manifold is an unknown brand 4-1 header with only about a 9 or 10mm thick flange and a pretty small contact area for the big washer to press on it.
Going back to stock manifolds is not an option, and I'm sick of bent/broken manifold studs and leaky manifolds.
The suggestions to build up the header flange are what I'd suggest if you're keen on keeping the leaky header. That said, you'd want to take the header in to a machine shop (moreso if you don't have a welder) to have them mill the spots you fixed to the correct size. If you try to sand the spots yourself you're likely to get one or a few off from the intake thickness, then you'd be causing problems all over again.
Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson
Re: Fixes for crappy L-series header fitment
edit
Last edited by broke on 27 Dec 2009 20:00, edited 1 time in total.
The IDx 10 concept is based on the 510 in the same way that the urinating I was doing last night was based on a 30 yr old single-malt scotch.
-McWicked
-McWicked
Re: Fixes for crappy L-series header fitment
I thought about that, my concern would be that I would then just be bending the washers where they're unsupported by manifold flange... or that I might warp the shit out of my exhaust manifold flange. Has anyone tried this? I don't have my own MIG welder, so if I'm paying someone to do it then it better work! (I'm also a curmudgeon )what about tack welding some washers onto the exhaust header, then grinding off the washer material that would interfere with the intake mani fit... fir out the exhuast mount points instead of shaving the intake. someone chirp in if warpage of the flange plate would be an issue.
Only because I can't tighten it up adequately without bending my manifold studs and having the big washer sit at a stupid angle.Sounds like you have a leaky header
To reiterate my earlier statement GOING BACK TO STOCK IS NOT AN OPTION! More power? If you haven't dyno tested my particular header and a stock manifold on my exact engine then perhaps that's not a wise statement to make, we all know how important dyno sheets are when making these claims perhaps no LOSS in power.. furthermore the stock manifold weighs a ton, looks like shit, (IMO) and won't fit my Y-pipe-less exhaust at all. Most importantly:so I don't see the improvement from a stock manifold. Do you have a picture of the header? If it is the common cheapy, you're way better off in every regard with a good stock cast manifold. More power, less noise, fits like stock
I NEVER HAD THE DAMN THING!! - Ergo, any header is better than exhaust ports venting to the atmosphere.
Please forgive my exasperation, but NZ is not blessed with a large number of L-series vehicles to cannibalize for parts, or I would have been down that road already. I guarantee there is not a single P510 in any wrecking yard in NZ, and probably only a handful of 4cyl L-series Datsuns in total. The only ones I've been able to find privately are all owned by people who want so much $$ for them that it's ridiculous, and I'd still have to spend more to make one fit my exhaust.
I'm not a total retard (Mum only dropped me from about 4ft when I was born), I've read all the advice here and in the How To Modify book saying that there are few gains on a street car, I just want to make what I have work so that I don't get hassled by "The Man" when driving around.
ThanksThe suggestions to build up the header flange are what I'd suggest if you're keen on keeping the leaky header. That said, you'd want to take the header in to a machine shop (moreso if you don't have a welder) to have them mill the spots you fixed to the correct size. If you try to sand the spots yourself you're likely to get one or a few off from the intake thickness, then you'd be causing problems all over again.
The IDx 10 concept is based on the 510 in the same way that the urinating I was doing last night was based on a 30 yr old single-malt scotch.
-McWicked
-McWicked
Re: Fixes for crappy L-series header fitment
A header I used to have had pieces of metal welded onto the flange to make up the difference - it was a piece about 1/4" wide at the correct thickness to make it plane out with the intake manifold.
Okay's point about aftermarket headers being a pain for little or no benefit is well taken. I have dealt with headers - and have gone back to the stock manifold time and again. Your case is different - header sounds like the only option. I wouldn't do any subtractive measures on the intake - add to the exhaust.
Okay's point about aftermarket headers being a pain for little or no benefit is well taken. I have dealt with headers - and have gone back to the stock manifold time and again. Your case is different - header sounds like the only option. I wouldn't do any subtractive measures on the intake - add to the exhaust.
Finished is better than perfect......
- 510-Trevor
- Supporter
- Posts: 1373
- Joined: 03 Mar 2007 18:34
- Location: Calgary, Alberta
Re: Fixes for crappy L-series header fitment
How about having some custom stepped washers made up or customize the ones you already have?
1972 Yellow 4dr
Re: Fixes for crappy L-series header fitment
even Nissan Comp header have a small piece of square stock, approx. 1/4 x 1/4", welded to the flange to make up the difference.
i'd take it for a fab/machine shop and explain what you are trying to do.
they would be able to add the necessary material, and do a quick milling if needed.
take the intake manifold with it, so they can measure and match the thickness.
ideally, if you a spare cylinder head, or something thick (1" plywood, 1/4" metal) with all the matching holes in it, would be ideal. then they could mock it up to see how it fits together.
the more you could give a shop, the easier it is for them to do it right the first time.
i'd take it for a fab/machine shop and explain what you are trying to do.
they would be able to add the necessary material, and do a quick milling if needed.
take the intake manifold with it, so they can measure and match the thickness.
ideally, if you a spare cylinder head, or something thick (1" plywood, 1/4" metal) with all the matching holes in it, would be ideal. then they could mock it up to see how it fits together.
the more you could give a shop, the easier it is for them to do it right the first time.
richard norrish
'68 'goon resto / '71 ice racer / '72 'goon project / '70 4-door rust pile / '67 520 project
----------------------------------------------------------------------
'68 'goon resto / '71 ice racer / '72 'goon project / '70 4-door rust pile / '67 520 project
----------------------------------------------------------------------
shardik wrote: My swap will be made of solid gold and it will run on puppy farts.
Re: Fixes for crappy L-series header fitment
I've had headers with both square stock welded to them (Just tacked in place works fine, shouldn't warp the flange), and had stepped washers (works, but not too well, as the washer itself may cock sideways on the stud and again not clamp down properly and bend the stud as did happen when I tried this on a Tri-Mil header - they are crap BTW).
If you really have to use the header, shimming up with spacers tack welded in place will work. Hopefully the flange itself is already flat, and of decent thickness to be flat against the head. The famous spot for all bad headers to leak is out the bottom of #2/3 exhaust ports. To help with this, when installing the intake/exhaust, tighten the 4 lower bolts/studs before the final tightening of the 4 upper bolts/studs, working from the inside out. Final tightening of the middle three (top) exhaust studs last. This pattern has helped in my problem applications in the past. It also really does help to use gaskets with metal crush rings around the exhaust ports, such as the Nissan ones or Felpro gaskets. I’ve not had much success with the full fiber gaskets myself.
I have to admit I've never liked headers - until I bucked up for the Nissan comp unit. I spent the big bucks, and it had been leak free since I installed it in 2005 (even after heating and bending the crap out of it to fit my taller Z22 block and not have the collector through the drivers side floor). Not a very good angle (but the only one in my build thread) of the header here:
viewtopic.php?f=27&t=530&hilit=69+resto&start=285
Byron
If you really have to use the header, shimming up with spacers tack welded in place will work. Hopefully the flange itself is already flat, and of decent thickness to be flat against the head. The famous spot for all bad headers to leak is out the bottom of #2/3 exhaust ports. To help with this, when installing the intake/exhaust, tighten the 4 lower bolts/studs before the final tightening of the 4 upper bolts/studs, working from the inside out. Final tightening of the middle three (top) exhaust studs last. This pattern has helped in my problem applications in the past. It also really does help to use gaskets with metal crush rings around the exhaust ports, such as the Nissan ones or Felpro gaskets. I’ve not had much success with the full fiber gaskets myself.
I have to admit I've never liked headers - until I bucked up for the Nissan comp unit. I spent the big bucks, and it had been leak free since I installed it in 2005 (even after heating and bending the crap out of it to fit my taller Z22 block and not have the collector through the drivers side floor). Not a very good angle (but the only one in my build thread) of the header here:
viewtopic.php?f=27&t=530&hilit=69+resto&start=285
Byron
Love people and use things,
because the opposite never works.
because the opposite never works.
Re: Fixes for crappy L-series header fitment
Apparently, you'd be surprised. There are very few headers made over the entire life of the 510 that produce gains over the good 4-2 stock, cast exhaust manifold. What gains are made are made at the top end, and these are only the NISMO/Stahl headers. Everything else pretty much just makes more noise. And while it is true that I can't speak about your particular header since even you don't know who made it, there are many crap 4-1 headers out there with thin flanges that give the same fitment problems you're describing and they're all very, very poor - bad all-around design if you've done any research into exhaust theory.broke wrote:To reiterate my earlier statement GOING BACK TO STOCK IS NOT AN OPTION! More power? If you haven't dyno tested my particular header and a stock manifold on my exact engine then perhaps that's not a wise statement to make, we all know how important dyno sheets are when making these claims perhaps no LOSS in power..
It's not like I didn't read your "I don't want the stock manifold" disclaimer, but that doesn't mean it's still not the best way to go.
something like this?:
http://www.the510realm.com/viewtopic.ph ... er#p125827
Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson