Y Pipe To Manifold Bolt Size

[bronc]

Can anyone tell me the size of the 4 bolts from the y pipe to manifold? I need to get some replacements before I go home this weekend to do some work on the truck.

 

[AllanD]

On a 2.9, 4.0 and 3.0 the Ypipe-to-manifold bolts are 12mmX1.75 thread, not sure about the length.

the one problem with hardware or autoparts bolts is that they have a larger hex size than the factory ford bolts, typically the aftermarket bolts will have a fat 19mm head.

the Factory ford bolts have a 15mm integral washer type head.

I've used 3.0 bellhousing bolts for this task in the past.
These are usually easy to find UNDERNEATH a ford taurus
in the junkyard that SOMEONE ELSE has pulled the transmission out of.
(why work if you don't have to?)

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[ZMan]

I recall the heads of my 2.9l bolts being 18mm, on my 4.0l the only socket I could get to fit was 9/16", and on my 3.0l 15mm was spot on. All factory bolts.

 

[bronc]

Yea see I had bought some bolts when I did the swap, they weren't threaded all the way to the head. I had them all bottomed out and there was still a slight exhaust leak. I could not find bolts threaded all the way when I looked this week. So I got some from Ford, they must have some gold in them or something though. 45 bucks for 4 bolts... But they worked. They 12 mm, not sure on the pitch but your likely right at 1.75. And the head is 15 mm and about 2 inches long.

But problem solved anyway. Thanks.

 

[AllanD]

On my 4.0 I'm not using the stock bolts.

I have Borla Headers and the holes in the header flanger are smaller
than stock, But I didn't like the Borla hardware either, So I'm using Surplus 4.0 Bellhousing bolts (10mmX1.50) with 10mm Flag Nuts.

If I ever have a problem I can just cut them off and replace them because the only thing they are threaded into is the nuts.

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[bronc]

Yea, that's one thing I would like about using smaller bolts with a nut and a washer is that you can cut them and no harm done.

 

[tonyd]

Thats the way I did it. m10 was a close fit. Flange bolts from True value. Made sense to me. A little removable blue locktite and done.Thanks for the suggestions.