So the bolts you removed from the head are M8 x 1.25 metric, but the threads in the head seem to be 5/16" x 20?  Maybe a PO (or mechanic) got there before you with the same goal of cleaning up the threads, but bungled the job by using a 5/16 x 20 tap.  The metric bolts might still 'fit' afterwards.

Still, I think it's more likely that your metric tap-and-die collection may have a 'visitor' from the SAE family that lives in the drawer next door

I get most of my metric nuts and bolts from a local dealer - BelMetric. They take small and large orders with the same amount of care. They have the manifold stud bolts as well.

52 minutes ago, Namerow said:

So the bolts you removed from the head are M8 x 1.25 metric, but the threads in the head seem to be 5/16" x 20?  Maybe a PO (or mechanic) got there before you with the same goal of cleaning up the threads, but bungled the job by using a 5/16 x 20 tap.  The metric bolts might still 'fit' afterwards.

Still, I think it's more likely that your metric tap-and-die collection may have a 'visitor' from the SAE family that lives in the drawer next door

Nope,  I'll have to video it for you doubting Thomas' (Tomi?)

anyone have a replacement for part number: 08214-83010, apparently Nissan said this was on back order. 

 

 

I'd like some further information about the factory hardware used to secure the exhaust manifold and intake manifolds to the head.  Can anyone tell me what markings are on the heads of the 6 bolts which secure the top of the intake manifolds to the head?  And, should there be flat as well as split lock washers used in conjunction with these bolts?

To secure the exhaust manifold to the head (3 points), besides the hex nut and split lock washer, there is a flat washer used.  What size OD and how thick? 

I used Nissan Titan truck exhaust studs and one use lock nuts on the ends of my N42. Altima smaller stuff in the middle. All bought at local Nissan dealership.

The ends were already wallered out so going with the bigger studs was a no brainer. The smaller Altima which is the same as OE Datsun was just a much better, newer way than lock washers and free spinning nuts from the factory. My opinion only but after years of checking, they are still nice and tight.

Edited June 19, 20222 yr by siteunseen

1 hour ago, inline6 said:

I'd like some further information about the factory hardware used to secure the exhaust manifold and intake manifolds to the head.  Can anyone tell me what markings are on the heads of the 6 bolts which secure the top of the intake manifolds to the head?  And, should there be flat as well as split lock washers used in conjunction with these bolts?

To secure the exhaust manifold to the head (3 points), besides the hex nut and split lock washer, there is a flat washer used.  What size OD and how thick? 

Here are some pics from my 7/70, after removing the intake and exhaust manifolds, I replaced the hardware in the locations that I found them. No lockwashers are used, except for the two capscrews that attach the thermostat housing. The thick exhaust manifold washers are 23.6mm OD x 9.0mm ID x 6.1mm thick on mine. The intake capscrews have "7" and "T" and "R" marks. Hope this helps.

Yes, that is helpful. What is the diameter and thickness of the flat washers used on the exhaust manifold only? Looks like 5 total - 1 front and 1 rear and 3 in the middle.

13 minutes ago, inline6 said:

Yes, that is helpful. What is the diameter and thickness of the flat washers used on the exhaust manifold only? Looks like 5 total - 1 front and 1 rear and 3 in the middle.

The thin ones are 21.5mm OD x 8.5mm ID x 2.5mm thick. Over the next couple of days I will mark up a picture with the occurrence of each type and post it here.

@Namerowregarding your original post about studs vs bolts for the upper six intake manifold fasteners, I found something interesting in the 1973 JDM S30 parts fiche. The nut (item 32) is described by two options, one a nut and the other "BOLT - fixing manifold". These pages are for up to 1973-2. Not exactly clear but interesting none the less.

The studs are shown on a different page for the cylinder head,

The JDM parts book has great illustrations and in a lot of cases more detail than the N.A. parts book.  It can be found here:

Thanks @hr369

Edited June 19, 20222 yr by CanTechZ

Haven't seen him around in a long time...

17 hours ago, CanTechZ said:

Here are some pics from my 7/70, after removing the intake and exhaust manifolds, I replaced the hardware in the locations that I found them. No lockwashers are used, except for the two capscrews that attach the thermostat housing. The thick exhaust manifold washers are 23.6mm OD x 9.0mm ID x 6.1mm thick on mine. The intake capscrews have "7" and "T" and "R" marks. Hope this helps.

From you picture, I see that of the 6 T R 7 bolts, only numbers 1, 3, and 6 have flat washers.  The other three didn't have a washer... of any kind?  Do you know if your intake manifold has been taken off at any point?  

Out of all the hardware on the car, that used by the factory on the intake manifold is most unusual in my opinion.