Now that the engine is out and on the engine stand, I'm planning to remove the air tubes from the exhaust manifold. As they have been in the manifold for 36 years, I expect they will be hard to remove.

Any suggestions before I begin? Any wisdom from those who have done this?

I plan to spray them with PB Blaster and possibly heat them with a small propane torch.

I understand that the threads are BPT. I'm considering driling them out and making them std metric. Any thoughts on this?

I think i cut them off and welded them closed. i had the manifold off so i could cut them off from the inside. good luck unthreading those rusty pieces!

When I picked up the manifold I have now the car was sitting in the junkyard for the past 25 years. The fittings were pretty frozen. I heated the manifold around them up cherry red and then gabbed them with a vice-grip to cool them fast and turn to break them loose. The cooling tends to get the fittings to shrink faster than the manifold can cool which seems to help.

Thanks! The heating / rapid cooling sounds like the right approach.

Personally, I was never able to get the fittings out - with any type of Penetrating oil - until I started using Kroil... With Kroil (Aero Kroil) they simply break free and turn out.

http://kanolabs.com

FWIW,

Carl B.

I've heard very good things about Kroil. Other than Eastwood & online, do you know who might distribute/sell it? I looked on the NAPA & Parts America sites and did not see it.

Or..... Just remove the manifold and get yourself a good flowing 6 into 1 header. Better air flow, looks better, allows for a new, bigger diameter exhaust pipe and all around better performance.

They start at about $150.

Dave.

Or..... Just remove the manifold and get yourself a good flowing 6 into 1 header. Better air flow, looks better, allows for a new, bigger diameter exhaust pipe and all around better performance.

They start at about $150.

Dave.

Even though I'm not going this route with my Z, I have to agree with Dave. And not to mention it just sounds MEAN!!!

I've heard very good things about Kroil. Other than Eastwood & online, do you know who might distribute/sell it? I looked on the NAPA & Parts America sites and did not see it.

As far as I know - it has to be ordered on-line from Kano Labs. But it's worth the wait, nothing else compares here in the U.S.

I've done side by side comparisons with several other types - nothing comes close.

FWIW,

Carl B.

Or..... Just remove the manifold and get yourself a good flowing 6 into 1 header. Better air flow, looks better, allows for a new, bigger diameter exhaust pipe and all around better performance.

They start at about $150.

Dave.

I have to disagree with Dave on this one as it relates to the headers.

I haven't seen any independent dyno tests that show headers producing more power on a stock or street mod'ed engine, than the OEM exhaust manifold, when you hold everything else the same.

In addition to better looks with the headers - you get more under hood heat, noise and usually bad fitting flanges on the cheaper headers. That usually leads to exhaust leaks, which also corrode and then blow out your studs. (cheaper being under $325.00)

Cutting the stock exhaust pipe open at the "Y" and going to a larger diameter exhaust system, with a free flowing muffler will pick up between 12 and 15 HP. Leaving the top off the stock Air Cleaner will pick up about 5 HP.

If your building a full race engine, and need to tune the exhaust header to specific RPM ranges... sure, go for it. Like the look of "headers" when the car is parked and the hood is up - sure, go for it.

Want less long term hassle, less nose in the cabin while cruising, less heat under the intake manifold/carbs, less heat under the hood and against the firewell - keep the OEM exhaust manifold.

FWIW,

Carl B.

As far as I know - it has to be ordered on-line from Kano Labs. But it's worth the wait, nothing else compares here in the U.S.

I've done side by side comparisons with several other types - nothing comes close.

Try CRC "Knocker Loose" it is a copy of Kroil and is available anywhere that sells CRC products. It DOES work as good as Kroil.

CRC also has a product out called "Freeze Out" (I think) that is good for "shocking" stubborn parts free.

They also have a new version of Knocker Loose that incorporates freeze out with knocker loose!

BTW, these products all cost at least 1/2 of what Kano charges for Kroil!

Regards,

Astrohog

My only thought is what are you guys going to do when the great powers that be. Decide you have to put all that smog gear back. With the stock manifold it is a matter of bolting the pieces back on. Yes, I do own all of them. After owning this car over thirty I can not honestly say it runs better or faster with out the smog gear. I only removed it because it took some time to find a smog pump.