Thanks for the info. I was looking at port designs etc. I came across some header info from F1 headers. They step up the pipe 10mm or two 5mm. This creates an anti reversion cone. Now they are running 20K+ RPM.
Reflected pulse wave tuning is the other reason for intentional changes in cross sections. It makes the most difference in long tube headers when you can take advantage of valve overlap. Long tubes would be hard for us to package though, you'd need primaries 40+ inches long. If you're into this stuff you should check out the exhaust theory link above.
Bolts were doable but a ratcheting gear wrench helped and some were awkward. That actually brings me to:
Header Install Time…
I tried hard to screw this up. I didn’t but I tried hard.
Bare block… Making me appreciate how that fine layer of Hawaiian mud really does get everywhere.
AFE’s come with a nice branded Fel-Pro gasket for the head and a crush metal gasket for the merge.
AFE’s instructions. No mention on torque so that sucks... For the record, the combo intake/exhaust bolts are 24 ft-lbs with a specific pattern from middle outward. Some sources claim the nuts are 23 ft-lbs and use of anti-seize should lower the torque required some as well. However, since you can’t get a torque wrench on half this stuff anyways, I don't think it much matters.
Old gasket is nasty.
After scrapping/light sanding, the rusty spots on the head got smeared with anti-seize before reassembly.
Couple studs decided their nuts would seize so these got loosened/reworked on the bench vise.
Gasket looks perfect. Nice couple pins to locate that.
Header landing pretty good.
But on the bottom side it’s almost touching the pan. I can’t tell you how this compares to stock since the manifold I’m replacing isn’t factory. That said, the old part was probably 1/2” - 5/8” clear and this isn’t. I liked the clearance better so it’s one of the few things AFE should do better (or at least reverify vs. stock). This kinda sucks as it messed up my exhaust clearance and I’m rubbing the pan. I wrapped it in about 6 layers of header wrap and I’ll re-optimize the fit later.
Since I’m unlikely to have things this far apart any time soon I pressure washed the heck outta the intake manifold…
Install seemed to go fine. Stuff kinda lands where it wants to land, everything torqued well. But then I’m looking at the alignment of the power steering bracketry and it seems like the manifold is low (bolt sitting at an angle)
Take a closer inspection and part of a port is showing. WTF? Note, you can see the copper anti-seize used on all bolts peaking out a bit.
It’s late and I’m mad at this thing so I call it a night and throw a couple pictures on the SoCal XJ forum on Facebook asking for details on how this is supposed to land.
Kind souls (including a few names I recognize from here) let me know that those gasket alignment pins are actually supposed to align the intake manifold as well. Boo.
Double boo? If you torque the mani without this being aligned you can snap off the alignment provision on the manifold. Well, that's scary…
I did mention that I tried to screw this up right?
Well, I still got lucky and nothing failed… After yanking this apart again you can where it tried to land in some slight marks on the gasket.
Thankfully it’s just marks and there’s no obvious depressions and damage to the gasket so that should be fine. You can see exactly how far I was off on the mating bung.
Buy the way, who the hell designs an alignment pin to have a 1/16” engagement? The protrusion through the gasket ain’t much and the feature on manifold is offset… Thanks Chrysler. I’m loving you guys right now.
Anyways, it goes back together fine on the second try. One think I did that turned out to be both good and bad was pre-installing some of the lower hardware so I could slide the intake mani down in place. The technique was good, but having it be a bit snug probably had it bite the pin protruding on my first try hence why it felt like it was home when it wasn’t.
Good to go right?
Wrong.
…and more to come,
Joel