Starting Carb Conversion: Flat Tops to Paltechs

[Dadsun]

On 1/24/2021 at 7:35 PM, Racer X said:

I forgot to mention, check the header and manifold mating surfaces for flatness. Using a straightedge with a ground flat edge check that all surfaces are flat, and square. Anything more than .002” or .003” off will be difficult to get sealed and kept tight.

Well, Racer mentioned it and now that it's off the car, the header does have some significant issues on the flatness from one end to the other. In particular the front most exhaust flange is pretty much worn away. I could have my friend braze another lip around it and then try to grind appropriately, but I don't think I'll get it within tolerance that way. Or could have a competent machinist, but that'd probably be a lot more hassle and maybe even higher cost than just buying a new header. Ugh. Wish I would have known what to check before paying to have it ceramic coated. 

I think one of you highly recommended a 6-to-1 header upgrade?

Btw, someone said it looks like the header has been leaking for a while. No, that's just how much carbon has built up in the engine. I've had the header back on a month and probably have <1 hour of run time, almost all of it in my garage while I was tuning the carbs.

[w3wilkes]

I've been very happy with my MSA 6 to 1 header and it comes already coated.

Motorsport! MOTORSPORT TBC Coated 6-1 Header, 70-76 240Z-260Z-280Z - The Z Store! Nissan-Datsun 240Z 260Z 280Z 280ZX 300ZX ( Z31 Z32 ) 350Z 370Z Parts

 

Edited February 8, 2021 by w3wilkes

[jfa.series1]

Here's the MSA 6-1 header installed on my engine. The flange thickness is a perfect match for the intake manifolds.

[Racer X]

2 hours ago, Dadsun said:

Well, Racer mentioned it and now that it's off the car, the header does have some significant issues on the flatness from one end to the other. In particular the front most exhaust flange is pretty much worn away. I could have my friend braze another lip around it and then try to grind appropriately, but I don't think I'll get it within tolerance that way. Or could have a competent machinist, but that'd probably be a lot more hassle and maybe even higher cost than just buying a new header. Ugh. Wish I would have known what to check before paying to have it ceramic coated. 

I think one of you highly recommended a 6-to-1 header upgrade?

Btw, someone said it looks like the header has been leaking for a while. No, that's just how much carbon has built up in the engine. I've had the header back on a month and probably have <1 hour of run time, almost all of it in my garage while I was tuning the carbs.

Interesting how the one flange looks flush where the tubing comes through, rather than protruding and then ground to make a flat ridge around the port (which aids sealing).

Sure, you could pay a competent machinist to repair it, and spend more money, but is it really worth it? I see it has emissions bungs, that are not being used. Getting a header that doesn't have them makes more sense if you aren't using the AIR system. Having tubular exhaust is all about maximizing air flow through the engine, and the flow past the unused bungs will be disrupted some.

As for what header, consider the engine as a whole, and choose accordingly. 

Personally I am considering a full stainless steel system from that guy in France. His systems look nicely done, and can be tailored to the engine build and intended use.

I just need to save the cash.

[Dadsun]

@siteunseen, are these the parts you bought? (FYI, I have the original 240z S30 2.4 liter engine)

Header:

https://www.thezstore.com/page/TZS/PROD/classic19d/15-6012CH

Exhaust:

https://www.thezstore.com/page/TZS/PROD/classic19d/15-6309

Gasket: this is the exact gasket I just bought last month... I may just leave it on and salvage it. https://zcardepot.com/products/manifold-gasket-intake-exhaust-oem-240z-260z-70-74?_pos=3&_sid=ee7b757b0&_ss=r

 

Edited February 9, 2021 by Dadsun

[siteunseen]

Yes sir, yes it is, and I love it. Has a high rpm raspy sound on my 2.4 and a totally different sound on the 2.8. I had a 20" resonator installed on the 2.8. It had a horrible drone on the interstate but the 240 is perfect. Music to my ears. It reminds me of the motorcycles I used to ride. I'd describe it as screaming bloody murder to slow down.

 

[siteunseen]

1 hour ago, Dadsun said:

@siteunseen, are these the parts you bought? (FYI, I have the original 240z S30 2.4 liter engine)

Header:

https://www.thezstore.com/page/TZS/PROD/classic19d/15-6012CH

Exhaust:

https://www.thezstore.com/page/TZS/PROD/classic19d/15-6309

Gasket: this is the exact gasket I just bought last month... I may just leave it on and salvage it. https://zcardepot.com/products/manifold-gasket-intake-exhaust-oem-240z-260z-70-74?_pos=3&_sid=ee7b757b0&_ss=r

 

Call MSA for the best service. Those guys are super nice to talk to. Give them your czcc member ID for 10% off. Your's is 34425. I got it below on a screen grab.

 

[Dadsun]

Ok, thanks.  Didn't know about the 10% discount!  Man, I could have saved a lot this past year.

What are your thoughts on this gasket instead of the Nissan OEM one?  https://www.thezstore.com/page/TZS/PROD/classic19a/10-2525

It apparently comes with the performance headers purchase.  MSA link says:

Quote

"Special installation gaskets are included (do not use original equipment type exhaust gaskets with headers)."

 

Just called MSA.... backordered.  And they don't know when they'll get them.  The coating vendor has them backed up.  

Edited February 9, 2021 by Dadsun

[siteunseen]

I've got 2 msa gaskets hanging on a nail. In my opinion they're flimsy. 

When you get your's, compare it to the oe one from zcardepot and decide. 

[Dadsun]

So, with MSA now telling me they are on back-order indefinitely for ceramic coated headers, I'm a bit stuck.  Anyone have other avenues they'd recommend? I could buy the uncoated for $300 then pay about $240 to get them coated, but that is just too painful on the wallet. 

I've been looking through eBay, but don't trust a lot of what I see.  Does this (see pic) make sense as a "square port style?":

 

Also, the MSA website description of their headers say: "The thick exhaust flange is flat machined to promote a consistent seal. It also prevents warping and eliminates the need for spacer height modifications."  Does this mean it will not have the raise lip around the square ports as my current one has? (see pic#2)

Edited February 10, 2021 by Dadsun

[Racer X]

9 minutes ago, Dadsun said:

I've been looking through eBay, but don't trust a lot of what I see.  Does this (see pic) make sense as a "square port style?":

 

The outer 4 ports in the picture look pretty round to me. 
 

Compare it to the ports on your header. 

[Zed Head]

35 minutes ago, Dadsun said:

Also, the MSA website description of their headers say: "The thick exhaust flange is flat machined to promote a consistent seal. It also prevents warping and eliminates the need for spacer height modifications."  Does this mean it will not have the raise lip around the square ports as my current one has? (see pic#2)

"Machined" suggests that there will be no raised lip.  Many headers out there for the L engines have a flange that is thinner than the intake manifold flange.  So the yokes don't sit flat and you can have sealing problems.  Sounds like MSA has addressed the problems.

Those eBay headers look sketchy.  Four round and two square, not right.