Exhaust Manifold Bolts - what size and material to buy?

[broncoli]

Hi all,

I've got a 1988 Bronco II, and I'm rebuilding the engine (heads cracked). I need a full new set of exhaust manifold bolts, but I don't have any of the old bolts to look at for sizing.

Could someone tell me what size (thread, head, pitch, length) the bolts are supposed to be? I read in one place that they're 3/8-16", but I read elsewhere that they're m10s of some variety.
Also, what material would you recommend for them? Stainless steel?
Lastly, if you could point me towards someone that sells them I would appreciate it.

Thanks all!

 

[broncoli]

In my search I was able to find this part number: N802904-S2
Which is for a M10 x 1.5 x 65 bolt. According to this site: https://www.fordpartsgiant.com/parts/ford-bolt-m10-x-1-5-x-65_-n802904-s2.html it is the correct bolt for the Ford Bronco II manifold.

Unfortunately they seem to be very hard to come by for any less than $10/piece. And i need 12 of them

Edit: This is not the correct part number or bolt.

 

[broncoli]

Ok, I've got what I needed by measuring heads and exhaust manifold at a junk yard. Here's the exhaust manifold bolt sizes needed for a 1988 Ford Bronco II 2.9L:
8: m8x1.25x75mm
3: m8x1.25x50mm
1: m8x1.25x30mm

 

[LeBronCo]

Did you find a set? I have an 87 and I'm in the same predicament

 

[Uncle Gump]

I think what he is saying is he bought individual bolts with the above specs from a place that sells fasteners.

That might be your best bet...

 

[LeBronCo]

Does anyone else concur with the sizes? I found them at McMaster-Carr.com.

 

[Uncle Gump]

You could always measure your manifolds.

 

[broncoli]

Did you find a set? I have an 87 and I'm in the same predicament

Hey, sorry for the late reply. Uncle Grump is right, I just bought specific bolts from McMaster-Carr. Here's my order invoice for what I got exactly, I got 1 of each. On test fit they seem to be correct for 1988 Heads/Headers.:

Medium-Strength Class 8.8 Steel Hex Head Screw, M8 x 1.25 Mm Thread, 75 Mm Long
91280A285
Medium-Strength Class 8.8 Steel Hex Head Screw, Zinc-Plated, M8 x 1.25 Mm Thread, 50 Mm Long
91280A546
Medium-Strength Class 8.8 Steel Hex Head Screw, M8 x 1.25 Mm Thread, 30 Mm Long
91280A085

 

[rstanovich]

careful using anything past grade 5 or when and if they break you will play heck drilling them out.

 

[LeBronCo]

Done and done. However it is still not running right. On any kind of incline it just won't power up. The entry gate to my property is on an incline. When I stop to open the gate, get back in and try to drive through it bogs, I have to gun it so it won't stall out. This has to be engine management. I ordered a new ignition module. I've done all the basics, fuel pressure is good, spark is good. It starts right up, idles, accelerates. Just not under load.

 

[bzzn87]

Rebuilding your engine sounds like a great project, and I'm happy to help you with the exhaust manifold bolts. The original bolts for a 1988 Bronco II are typically 3/8-16" in size. However, there might be some variations, so it's a good idea to confirm this by double-checking with an expert or a Ford dealership. As for the material, stainless steel bolts are popular for the material due to their corrosion resistance. Regarding where to buy them, check out scrooz.com.au, Australia's Online Fastener Store. They have a wide range of fasteners and are known for their quality products. I'm sure you can find what you're looking for and good luck.

 

[NETX_S4]

Hey, sorry for the late reply. Uncle Grump is right, I just bought specific bolts from McMaster-Carr. Here's my order invoice for what I got exactly, I got 1 of each. On test fit they seem to be correct for 1988 Heads/Headers.:

Medium-Strength Class 8.8 Steel Hex Head Screw, M8 x 1.25 Mm Thread, 75 Mm Long
91280A285
Medium-Strength Class 8.8 Steel Hex Head Screw, Zinc-Plated, M8 x 1.25 Mm Thread, 50 Mm Long
91280A546
Medium-Strength Class 8.8 Steel Hex Head Screw, M8 x 1.25 Mm Thread, 30 Mm Long
91280A085

Looks like each of these come in packs of 25. Are you not able to order individual quantities? I will be reinstalling everything on my block before too long, and only 4 of my original bolts broke when they were coming out. Do the others need to be replaced anyway, like the head bolts?

 

[89Bronco2Micheal]

Hi all,

I've got a 1988 Bronco II, and I'm rebuilding the engine (heads cracked). I need a full new set of exhaust manifold bolts, but I don't have any of the old bolts to look at for sizing.

Could someone tell me what size (thread, head, pitch, length) the bolts are supposed to be? I read in one place that they're 3/8-16", but I read elsewhere that they're m10s of some variety.
Also, what material would you recommend for them? Stainless steel?
Lastly, if you could point me towards someone that sells them I would appreciate it.

Thanks all!

I have an 87 B2 got it about 5 years ago its the one on my profile pic. Original owner told me heads cracked while under warranty took it back to dealership had new heads put on I think he said they were Jasper heads. It now has 135k miles on it.