Is this a factory head bolt??

[Coltsfan1]

Is this a factory head bolt or an early style ARP?

Thanks Chad

 

[Jan Larsson]

I would say no ... looks like an ARP bolt ...

I bought 1 of each NOS bolts as reference recently ... I'll see if I got a "headshot" of them to post.

 

[Coltsfan1]

Jan the next time you come to the states I'm offering u a free unlimited stay at my place. Plenty of rooms, horses to ride :cowboy: and gun range.......only catch is to pick your brain and you give a seminar.

I'm thinking it's an are. The strange thing is the bolt heads that are under the valve cover don't have the same A stamp. Don't know why.

 

[Coltsfan1]

Sorry arp

 

[Jan Larsson]

Happy for you to pick my brain, appreciate the invite and will let you know when next in your neck of the woods....were stranded at O'hare just over two weeks ago due to late in coming flight so spent the night at the airport (hotel) and got on the first flight out morning after.

 

[Jan Larsson]

Had a look and I only have a side view of the NOS bolts I have no photo of the heads I'm afraid ... would need to get them out and snap some but wont be able to until maybe next week

 

[Jan Larsson]

Had a quick look on ebay ... here's one of the 3 different part numbers for the head bolts and you can see the head so looks like yours might be the original bolts if you compare ...

New Genuine GM 25527831 Bolt | eBay

Keep in mind that the original bolts are torque to yield (so stretched to get the right torque reading) and should not be re-used ...

I would go with new ARP's to be on the safe side.

Hope this helps

 

[Coltsfan1]

I'm trying to determine if mine heads have been off before or if these are stock....not changing. I looked at that ebay link but pic is to dark....