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53guy
August 26th, 2006, 05:57
Does anyone know the header/manifold bolts size and thread pitch? I recall that there are two different sizes from the last time I did this, but I could be wrong. They are all factory bolts and sizes, so I need to clean out the threads in the block and I haven't pulled the header yet so I can't tell what the sizes are. I looked in the FSM, but didn't find anything. Does anyone have it off the top of their heads or know where I could find it?

brokexj
August 26th, 2006, 06:03
I know the studs are 3/8"x24 fine and I am thinking the bolts are standard 3/8 x 16", I'll go look in the parts bin and pull one to double check.

53guy
August 26th, 2006, 06:05
thanks bud.

brokexj
August 26th, 2006, 06:14
I know the studs are 3/8"x24 fine and I am thinking the bolts are standard 3/8 x 16", I'll go look in the parts bin and pull one to double check.
That's right, just checked.

53guy
August 26th, 2006, 06:59
Awesome man, I appreciate it. There's like two studs, right? And the rest are the bolts. Isn't bolt 6 and 7 the studs? They are the only two with different torques than the rest.

5-90
August 26th, 2006, 13:43
OEM studs are 3/8"-16 on the end going into the head, and 3/8"-24 on the end that takes a nut (no, I'm not sure why, either.) You can make new ones out of 3/8"-16 "allthread" - I used brass, because I like it more for exhaust work. Cut to 2" or 2-1/4" long.

Screws are, as I recall, 3/8"-16x1-1/2" or 1-3/4". I favour brass or bronze for those as well - there are a multitude of my posts on the subject, and someone started a thread - I weighed in on the engineering reasons for doing so.

MAKE SURE you either put those little dish washers back on, or get new ones! I'm working on a useful substitute using Belleville Spring washers (which are better for the job, but a touch more expensive. Saving a few pennies on job isn't much - saving a few pennies on a half-million repeats does add up...) to more evenly distribute the clamp loads and prevent side load on the screws due to differential expansion of the intake and exhaust manifolds - but I haven't gotten round to it yet. Expect a writeup on the WiP website (link in sig) when I finally do...

5-90

53guy
August 26th, 2006, 17:16
Yeah, I got them done today. Appreciate all the responses. Replaced the bolts, kept the dish washers, replaced the nuts and washers on the studs. All wonderful now and I am affraid my Jeep isn't running when I'm on the highway....I can't hear it! Its finally quiet again.