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Very sad to discover the flanges aren’t flat. All bolted up with no gaskets, I’m finding at least .015” gaps. The nice GM mls exh gaskets aren’t going to seal.
For the price and wait time I expect a flat flange. Right?
At least you got yours. I ordered my Chevelle header in July of last year. They kept sending delayed messages of one month or so, then another and so on. I finally got fed up and told them to cancel. Ordered from Sanderson and got them in 4 days. So disappointed with Holley. And hearing a lot of reports of their quality going way down.
I have used a lot of Holley LS stuff. It’s always very nice.
This is a disappointment. I’ve seen $100 eBay headers with flat flanges.
It appears that a whiz wheel was used on the mating surface after welding.
I may see if my machine shop guys have a belt sander and can fix this. I’m really not a fan of the squishy gaskets…..
Yeah a flat file and some time, a machine shop with a mill, or belt sander like you said. With that said, you couldn't pay me to put another set of these junk Sanderson's on a S10. I've hated them since after the first year on my truck.
But I agree it's a little rediculous they aren't flat.
Definitely expect the flanges to be flat. That's pretty basic. Especially frustrating after a long wait.
On the bright side, Hooker quality has improved from 20 years ago. My first LS1 headers were Hooker long tubes. The neither flange was flat, all the primaries were full of slag that had to be ground out, one collector had holes you could see day light through that had to be welded up and one of the O2's bungs wasn't threaded.
Did you get these figured out? I was a little surprised you bought these, and not those Stainless Flowtech long tubes. I think you mentioned you didn't like the slip tubes at the end though.
I can't vouch for horsepower gains or losses on the S10 swap headers from Speed Engineering but I can say the headers I have used from them in the past always had flat flanges. Their S10 headers I'm pretty sure also come with Vband couplers right out of the box which is pretty cool.
I agree on the no squishy gaskets. That is garbage from yesteryear.
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Hooker Blackheart S10 headers 
