late 70's 454 questions.

[nate1977]

I'm building a 1977 Chevy Stepside 2wd shortbed that is near to my heart. I got a 454 out of a 79 Chevy crew cab dually complete and ready to drop in, if i want. I'm going to tear it down first. I'm on here cuz of two things. 1:The headers I got with it arenot typical headers. They are long full length, but the front 2 exhaust tubes and the rear 2 tubes join toether, and then those two connect at the collector. The outlet is not the typical flat end, 3 bolt collector. Instead, they have a donut and two bolts for the flange. Anybody know what brand they are? I'll have pics available soon. 2: The back of the block by the rear plugs has "High Perf Pass" stamped in it. Have I found a desirable block or is it run of the mill? Any answers will help. Thanks.

[ccz145a]

Sounds like tri-y's, can't think of brands that make them. Supposed to good at high revs. The stamping is no indication that you have a 4-bolt or special block. You need the casting numbers for that info. No worries, though. With the right heads, a 2-bolt will be powerfull enough.

[VileZambonie]

It's a good indication that it's a good core rebuildable block with good breathing heads but we'll need casting #'s to be certain.

[Captkaos]

All truck blocks were Hi Perf Pass so it really means nothing.  It is most likely a 2 bolt, being a 77, but it really doesnt matter.  The 2 bolt will still make more than enough power to get you in serious trouble.

As for the headers, they could be Thorley (they generally use flanges though) or Hooker.  There should be a Part number stamped on them.