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Missing one exhaust port liner on N47 head


oldhemi

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I just picked up a N42/N47 engine. When I took the EFI intake and exhaust manifolds off, I discovered that there is a port liner 95% missing on cylinder number 5.

I have been reading and reading and reading about the liners NOT affecting performance from several experts on several boards. So, will one missing liner affect performance?

 

A little background info:

This is a contingency motor if I have some problems reviving my 260Z's motor which was rode hard and put away wet 19 years ago! I ran Weber 40DCOE's, a 3/2 header with plugged emission ports and never got around to installing a cam in it back in 1976. I was pretty happy with the way it ran and have no plans to increase the performance over what I had. Of course, I want to maximize what I have. Technology and information has come a long way in the decades since I last worked on the car!

 

I have a square port header installed on the 2.6 that I would use if I have to run this 2.8 motor. There was a very recent thread that further backed up older threads regarding running round port exhausts with square port headers. However, Paul R. (Braap) added the little line: " round port liners line up perfectly with the square port header". So, now I am a little worried about exhaust leaks around the port missing the liner if I have to use this motor. Comments on this new bit of info?

 

Thanks in advance for any help and or comments.This is a great site with a whole lotta information!

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Thanks for the replies guys. PO had a LS1 installed and has no idea what happened to the liner - he has all of his work done for him. The gasket does show more exhaust leakage than the other cylinders, but not to the outside edges.

I have no idea why someone attempted to remove that liner. The part where it attaches to the head on the bottom is still there. Maybe a mechanic bent it when installing a gasket. The exhaust manifold has the cold start "flapper" welded closed.

I have read tests where the liners were removed and the head did not flow any better, dont know if they do worse either. Since this will not be a "built" motor, I am more concerned with exhaust leaks. I dont think that one port not quite equal to the others will be a noticeable performance detriment.

Heck, I dont know at this point if the motor is trash. After seeing the liner missing, the exhaust manifold "mod", the fouled brand new looking BP8Es plugs and the broken stud with goop on what looks to be a new water pump - I gotta wonder about this $100 motor! I have to at least wonder about the "mechanic" that has been working on it!

I wish I had a camera that worked - Santa did not have the budget for a new one this year.:-|

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The liners on some heads can loosen up on their own over time with enough stress / heat and cool cycles. It's possible it just fell out on its own. Might even still be in your muffler.

Shouldn't have any problems with exhaust leaks, even with a square port header on a round port head. All you have to be sure of it that the header flange is straight, that there isn't any corrosion (or debris) on the head mating surface and that it gets evenly tightened down.

Bottom end might still be in good shape though. If the PO didn't foul it up too bad that is.

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I appreciate all of the comments and the kind offer of a very cheap head. I am leaning towards Blue72's hypothesis that the damn thing just broke.

 

This is a contingency motor and I do have positive news on my old motor: I soaked the pistons for a week with ATF as a precaution. Its not stuck at all. Turned over very easily by hand yesterday using the crankshaft pulley nut. I will turn it one revolution every day this week. I dont think I NEEDED to do this treatment, but I was accessing the rust situation at the same time and was in no hurry. Rust is typically bad for a DD Connecticut car. But I knew that when I stopped driving it. Anybody got a rust free front belly pan?

I have a ways to go on determing the health of the 74,255 mile L26. All things being equal, I gotta wonder if I would feel a difference with the L28........

Edited by oldhemi
spelchek
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  • 3 weeks later...

I had the same problem with my N47 head... the liner was made to burn particle who was not burned the first time it work with the EGR in some way... i pulled out all the other one to have the same flow in the head but i dont really know if it affect the faverage flow of the head... i think bigger intake with bigger exhaust can only help ur engine but if u go this way dont forget to atleast do a little port and polish to help

 

 

sorry for my english lol

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