1986 305 install headers

[1986GMCLB]

well now that i see what i have to do with the bracket to ac do i still need to put in a spacer too?
Now for the fun. on passenger side back by firewall the first bolt hole is it to be the same size hole as the rest. i cant get the bolt started like the hole is smaller. and yes im putting it into the right hole (haha) not where the manifold was. thinking maybe i need to run a tap in it to fig the size and or clean threads since old manifold was covering it..

[bilfman]

Yes with headers you will often have to fab a spacer if required. As to your rear bolt problem. Did you tighten the other bolts? If you did, don't. Start all the bolts before tightening. Another thing I always do with headers is start with the front and rear bolt No Gasket, I'll explain in a sec. Do the hardest one first, which in almost every case is the one closest to the firewall. This lets you move the header and start the most difficult bolt.

As for the gasket, many have a notch in the front and rear hole so you can start those 2 bolts and then slide the gasket in from the top. If the gasket you have does not have these just snip out the bottom and make your own slide in gaskets. I'll supply a primitive drawing of what I mean. Hope that helps...

[1986GMCLB]

Originally Posted by bilfman

Yes with headers you will often have to fab a spacer if required. As to your rear bolt problem. Did you tighten the other bolts? If you did, don't. Start all the bolts before tightening. Another thing I always do with headers is start with the front and rear bolt No Gasket, I'll explain in a sec. Do the hardest one first, which in almost every case is the one closest to the firewall. This lets you move the header and start the most difficult bolt.

As for the gasket, many have a notch in the front and rear hole so you can start those 2 bolts and then slide the gasket in from the top. If the gasket you have does not have these just snip out the bottom and make your own slide in gaskets. I'll supply a primitive drawing of what I mean. Hope that helps...

Yes i just thumb on bolts i dont have a problem with the gasket. Its just that last bolt by firewall..
I have been told it may have some crap in threads to run a tap in it
3/8-16
see i have the truck on a lift and started with back bolt from under the truck then went on top to thumb on rest.
Just this passenger side is being a pain..

[bilfman]

I'd start with the trouble bolt first. I would have some doubt about crap in the threads. Just because a bolt came out of there. Probably just a slight alignment issue with the gasket or header itself.

Another trick is tapering the bolt a wee bit with a grinder. This lets the bolt by small alignment issuew. Make sure to screw a couple of nuts onto the bolt before grinding, that way you can turn them off and fix the threads, kinda of like a cheap die.

[1986GMCLB]

no bolt came out of there. the hole was covered up by the manifold. that back bolt was smaller. on the manifold. there are 2 holes back there one for the manifold and one for the header

[bilfman]

Ahhh.

Yeah probably has to be cleaned out