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One thing I found helped a lot was getting the bolts started but not in anywhere near all the way. It helped getting them all started without them hitting the primaries.
You can use a drill to open the header bolt holes up, but I wouldn't. It'll be impossible to get the primaries centered over the exhaust ports if they can shift around some.
I had to push or pull on the headers to get the bolts started. Once the headers get a few heat cycles on them they'll reform a little bit and got better (which is why you have to go back in and tighten them all again after a few weeks).
Mine are all slotted slightly except the end holes. As long as you don't drill out the holes on the ends those bolts will keep the ports lined up. Start all the bolts with the header pulled away from the head as far as possible and tighten the bolts that are closest to the tubes first.
Thanks guys. I'll take my time on that. Don't want to mess anything up.
I came across oem manifold gaskets. Will those work and or be best for the longtubes? I know I already asked about gaskets. But wondering about the oem gaskets.
Last edited by 1993C4LT1; Jan 30, 2026 at 07:11 AM.
Not a fan of how close it is to that black line. Which has wiring inside of it. None of these bolts want to go in straight. It seems the bolt heads are too wide, or I need to dent, basically all of the driver side primary tubes. What a pain.
Always use washers. Not sure why, something about clamping force or something that a mechanical engineer could explain better, but yeah you want to use the washers
Hang it on a middle bolt, loosely. Then try to work from the outside in on bolts, again all loosely until you get them all threaded in. Sometimes you'll have to do the 2nd one from the outside first and pry on the headers to get it to line up. Once they're all actually grabbing, them you can start getting them tight. The flanges are not gonna be perfectly flat and straight until they've heat cycles a few times and relaxed. Worth noting, you're gonna have to come back and retighten these bolts a few time once they're all on.
