Stud pattern on exhaust manifolds

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therman731
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Joined: Sun Nov 23, 2014 10:04 pm
Car: 1994 Nissan Quest

Stud pattern on exhaust manifolds

Postby therman731 » Sun Jul 12, 2015 3:37 pm

I have a 94 Nissan Quest with a VG30E engine and like a lot of owners of the Quest/Villager I am having some issues with an exhaust manifold. Mine developed a leak in the bellows in the flex joint. I managed to remove the rear header with some effort and have obtained a replacement. In the course of removing the old header, I torqued off one of the studs. Also, I found that the two outermost studs at the extreme ends of the header had long since sheared off. I initially tried to extract the stud from the engine block without success. The particular port I am focused on is the left most port on the engine. In this instance, the port has four tapped holes of which only two are required to secure the header. I have a plan of attack to drill out the stud completely but to do so with some accuracy, I need to know the precise bolt pattern for the studs. The diagonal dimension is about 78.29 mm center to center estimated from the gasket but the pattern is rectangular; not square. Can someone provide me with the horizontal and vertical stud spacings? Fiddling around with whole numbers, 57.6mm W x 53mm H seems to come close.
Thx in advance.


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AZhitman
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Re: Stud pattern on exhaust manifolds

Postby AZhitman » Sun Jul 12, 2015 10:42 pm

Welcome aboard!

I can't imagine any resource that would have that info. I suppose if I were doing it, I'd use the manifold itself to get a measurement, even if it meant laying the flange face-down on a piece of paper and tracing the holes.

I've had success with this process: https://www.youtube.com/watch?v=VzwEskjits4
Requires no precision measuring, and should accomplish your goal.

Let us know how it goes!

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yellowdatsun
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Re: Stud pattern on exhaust manifolds

Postby yellowdatsun » Thu Oct 08, 2015 12:51 pm

Horizontal and vertical spacing? For the bolt centers? No idea what you'd need those dimensions for.

Nissan had a well known problem of VG30 exhaust studs shearing off, it has happened to me. The later VG33 engines went to a 10mm stud, instead of the 8mm you have. If you can get it out without damaging the threads, just use a NEW stud of the correct size. If you butcher it, upgrade it to the 10mm stud of the later engines.


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