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L20B Exhaust Bolt Size and Lenght?


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#1 jcd0402

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Posted 18 October 2017 - 08:22 PM

Quick question that I just can't seem to answer through the search function. Does anyone happen to know the bolt size and length for the exhaust and intake manifold. Im asking about the bolts that mount to the engine head. 

 

Thank You!


You know this is a beautiful car; it's still got a good engine but until we get that piece that fixes the engine its not going anywhere.


#2 DanielC

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Posted 18 October 2017 - 11:49 PM

The thread diameter and pitch is probably M8-1.25.   The length you will have to determine.  Going into aluminium, I would suggest the amount of thread into the head is at least twice the diameter of the bolt.   Since you are not using the stock bolts, make sure the bolts do not bottom in the hold before they are tight, and clamping the manifolds to the head.   Do not use generic hardware store bolts.  Get bolts with a marking on the head of the bolt of 8.8, or 10.9.



#3 Crashtd420

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Posted 19 October 2017 - 02:50 AM

Pretty sure daniel is right on the thread size...
I bought studs for my head.... there are also yoke washers that are used...
Not sure how important they are....
I think they matter most for the bolts/stud holding both the intake and exhaust.... I assume it's incase they are a different thickness as the washer is kind of cupped on one side...
Get right from nissan dealer.. cheapest price but I think it's a bag of 5 or 10 or something.....
Either way part # 14037-N3600

#4 Stoffregen Motorsports

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Posted 22 October 2017 - 09:12 AM

If you are talking about the bolts shared between the intake and exhaust manifolds, consider switching to studs. Two common problems with those bolts on an L series is that they break and also the threads in the soft aluminum head can strip quite easily. Studs will eliminate both problems. One added bonus to studs is that they help locate the gasket during install.



#5 racerx

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Posted 22 October 2017 - 09:32 AM

What a stud!

#6 scooter

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Posted 22 October 2017 - 06:52 PM

Studs ftw!!! Do NOT get stainless ones, they will gall and snap off. Cadmium ones are good though.

#7 Stoffregen Motorsports

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Posted 23 October 2017 - 07:55 AM

I hate stainless fasteners.



#8 DanielC

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Posted 23 October 2017 - 10:02 AM

"Stainless" is a very generic term.  It is used on many different alloys of steel, that are rust resistant.

The problem with steel alloys is that to increase the strength of alloy, you add carbon.   But carbon makes steel rust.  So, a cheap way to make "stainless" steel is to reduce the carbon in the alloy, but that makes the steel weak.  However you can add chromium, vanadium, and many other rare elements to higher carbon steel, and that will make the steel also rust resistant, and strong.   But these rare elements are expensive to add, and also require much more quality control when making the batch of steel, and that too increases the cost of quality stainless steels even more.

 

Nissan has used a special stainless steel thicker than normal nut on the studs at the bottom of the exhaust manifold  This nut is stainless steel, and not only is it strong, even after years of use, it does not seize on the threads of the studs on the bottom of the exhaust manifold.

 

On the other hand, I used to work in a boat shop.  Almost all the fasteners on the boat hull were cheaper stainless steel.  You had to use a grease on the threads of the fasteners, or commonly, the nut would gall on the threads, and stop turning.   But because cheap stainless steel is not that strong, it was easy to break the bolts, and just get a new bolt.