Need exhaust bolt depth inside head

[gmcman]

I know we have 33MM exhaust manifold bolts, what I need to know is how deep the bolt hole is inside the head. I'm replacing these bolts and I have a choice of 30MM or 35MM and I really don't want to cut the bolts if I don't have to.

30MM may be too short but not sure. Anyone working on the headers or has a cyl head laying around this info would be helpful..need to know this before I order the bolts.

Thanks.

 

[TangoBravo]

Why not pull a bolt and mic the hole? Really though I would think there is a very high probability that not all the holes will be the same depth. A better way to go about it without pulling all the bolts would be to see how much of the stock bolt actually goes into the head. If you have enough to loose 3mil then I would get the 30mil bolts. If it were me I would just pull all the bolts and mic every hole just to be sure. But I also work on multi million dollar engines for a living and being wrong can cost BIG $$$$.

 

[The_Roadie]

Why not buy them from GM and get the ones with the pre-applied heat-activated thread locker specified by the factory? I'm often frugal (not cheap) and that's what I did.

 

[TangoBravo]

Why not buy them from GM and get the ones with the pre-applied heat-activated thread locker specified by the factory? I'm often frugal (not cheap) and that's what I did.

The heat activated thread lock isn't exactly hard to come by, and if your going to replace the flange bolts why not do it with upgraded hardwhere, ones that chevy would have used if they didn't have to save .32 a bolt. Upgrading hardwhere is easy, removing broken bolts from your head is usually not.

 

[BRomanJr]

The heat activated thread lock isn't exactly hard to come by, and if your going to replace the flange bolts why not do it with upgraded hardwhere, ones that chevy would have used if they didn't have to save .32 a bolt. Upgrading hardwhere is easy, removing broken bolts from your head is usually not.

I agree with the Roadie on the use of the GM bolts, IIRC they are selling an improved version, not the same as were originally used.

 

[TangoBravo]

You do realize that there is nothing special about the GM bolts right? You really can do better for almost the same cost. Just sayin, gunna do somethin do it right, improve when you can.

 

[gmcman]

I wasn't aware GM improved on the bolt, will definitely check into that. Reason I want to take it one step higher is I already have a bolt that broke on it's own, who knows what's going to happen when I pull the rest of them.

This is the bolt I plan on purchasing....