I know this is non 3rd gen but i have a 68 firebird im restoring and i wana put headers on and ive herd of BlackJack headers they seem nicely priced but i was wonderin if these are good quality. The engine in the car is a 350. Also what size exhause should i have i was thinking 3 inch exhaust is that too big?

 

My experience with blackjack was not good. It didn't matter how good the gaskets or how many times we torqued, they always leaked. With Hooker, I never had to fix a leak. Felpro steel core gaskets never let me down. I would probably go with 2.5". Good luck Chris

 

If your Black Jack header (or any other header) seems to have a less that perfect flange or collector sealing bead, it can be trued up with bodyman's metal file and a DA
Sander before you install them. Always use quality header gaskets like MR.Gasket.
Retorque the header bolts a few time after
the motor cools overnight the first couple times. If after this the motor blows header
gaskets , check the AIR/Fuel RATIO.
Most leaky exhaust gaskets are caused by
over rich or over lean mixtures which both
cause the exhaust to be too hot! Back pressure has nothing to do with it.

 

I used to have Blackjacks on my '68 Camaro in high school.They're inexpensive, but not very well made.
Embossed Copper Gaskets are the fix for thin header flanges.They're about $45 a set, but they'll seal if the flange is reasonably flat and like F-BIRD'88 says you'll need to re-torque the bolts a few times (at least).
If you have access to a sandblaster, get rid of that flat black flaky paint that comes on those headers.It'll cook off pretty quick.
If they're cleaned up well and sprayed with some 1300 degree VHT paint,they'll look ok,though you may have to touch 'em up now and then.
The biggest problem I had with mine, were due to the lack of clearance around the spark plugs.Plug wires were getting fried often and I needed to modify a box-wrench to get to a couple of the plugs.
True Dual 3" exhaust is pretty loud.Flowmaster makes a couple of nice 2-1/2"
systems for early f-bodies.
http://www.flowmastermufflers.com/fmtest/DOCS/SET.html
-Rich-