First, be sure you bought the correct gaskets.  The oval port Hedman headers you have require an oval port gasket.  If you install rectangle port gaskets, you will have 32 exhaust leaks, one at each corner of every port.

I think the gap you are seeing is the thickness of the welded bead inside the header tube.  That is the only part of the header that touches the gasket surface.  There will always be a gap between the header FLANGE and the HEAD.  That is so there is less surface area to be compressed and will allow the 3/8" bolts to do the job.

Be sure to use anti-seize compound on all bolts going into aluminum heads. Those Edelbrock heads do have stainless steel inserts on the exhaust threads, so you don't have to worry about overtightening and stripping the aluminum heads.  Tell #7 and #8 hello for me.  I have spent many hours with those four bolts.  Bolts with 3/8" hex are alot easier to install on those than are 7/16" hex head bolts.

You said you bought the copper gaskets, I'm curious does anyone recommend using the hardware and gaskets supplied with say a set of JBAs? Someone told me to toss them and get copper.  Also said ditch the hardware and get locking type. I have a 5 oh and JBAs. Recommendation?
Thanks

Last edited by KStang (11/20/2013 1:54 PM)

The gaskets which came with my JBA shorties have worked quite well; however, what Steve describes is different than what came with mine in '07. The best way I can describe mine is that they are metal coated with 'fuz'. They look like they wouldn't hold up, but I've had them off and on a few times and I've never had a leak.

So, since it sounds like they are using different gaskets, I guess this post is moot 

I just bought those same JBA shorties and decided to use the provided gasket.  I normally use the fel-pro (1416?) but since these were new I gave em a try.  So far so good but I only have about 90 minutes on them.

Last edited by JVince (11/21/2013 8:30 AM)