I know that there are many many header instal threds and even some awsome stickies but non of them quite got me the answer that i was looking for anyway, i have just bought some doug thorly ceramic longtubes for my 85 z28 im just running a waterpump and alternator all a/c and smog equipment is gone ive got the car up on jackstands and have taken evrything out of the way i was just wondering if anyone here has installed thorly third gen headers and if so how did you install them its driving me up the wall any help would be very very much apriciated thanks a lot guys

 

Put em on my 85 firebird few yrs ago.... You have to lower motor on top of em. I'll help you as much as possible. Have had my engine out a few times and this is the only way,as with many longtubes on third gens. Also be aware that the number 7 spark plug is really close to the primary tube. Unless your using angle plug heads, I recommend using a couple extra header gaskets on the drivers side next to the head. And be sure to use the ones they send you with the headers thier the best.....I'm still using mine from 07 lol.

 

i am using angle plug heads and i agree those gaskets port match exactly , did you have to modify anything as far as fitment goes if so do you have pics of the spots you did thank you so much for your help btw how do they look and sound on your setup .thanks again iv been working on this car for 10 years my grand-dad gave it to me prior to his passing and told me to take care of it since then ive been chippin away at it lol and im really close the exaust is the only thing missing and i have them now so im prety antsy
thanks again

 

Didn't have to modify any part of the headers. They'll fit perfect with angle plugs too(better than mine).
I'm running 3" duals with magnaflow xpipe and 3" dynomax bullets that run alongside each other on the passenger side of the trans tunnel and turndowns at the rear axle. I love the way it sounds. Kind of a "rolling-raspy sound"
Be aware though that the ceramic coating may flake off after a while.
Also I had to notch my crossmember to get good ground clearance.

Here's some pics...

 

excellent thank you so so much finally got em in btw that bird looks like it wouldnt want to stay on the ground lol whats she run and whats ur setup as far as powerplant she is a beautiful car ,probably has an attitude problem to lol

 

6.93@ 97mph 1/8th and high 10's @122mph 1/4 1.49 60' footbrake
360"sbc (.060") 350 11:1 solid roller with brodix IK 200's
Tci 10"converter th350 with 4:11 moser 12bolt
275 Hoosier drag radials.
What's your combo and did you have to lower engine on them or did you find away around it?

 

400 (60 over)
comp cams
9.2/1 forged mahl pistons
195cc afr comp heads
holly 750 (blow through)
wieand manifold
Moter will be toped off with vortech blower (8 psi and intercooled)
have not been to the track yet but hoping for 12's
looking for around 300hp at the ground when its all together and tuned up
and i did have to take the engine out and lower it ontop of them it went much eaisier that way lol.
what are you doing to get that car to hook ??

 

Edelbrock Nonadjustable torque arm Lakewood lower control arms and lower control arm relocators,S&W antiroll bar,factory shocks and springs. Car weighs 2950 without me.

And I think your car is gonna be at least an 11sec car and 10's with a good tune.

Planning on a NA 421" with 18 degree heads in a couple yrs myself and low 6's with any luck!