Jeepguy asked if I would oversee and assist him with a manifold swap.
He brought his friend Max along and we got started around noon Saturday. He had wisely asked what he needed to bring along and I suggested some RTV and spray Copper Coat.
They arrived and the first thing we did was remove the hood.
Anyone who has worked on an FSJ know that the hood usually gets a few shots in ie; bumps on the head and possibly some scalp so we pulled the hood and sat it on the bed rails.
The manifold we were swapping in was an Edelbrock Performer AMC model 2131. The seller had said he'd bolted the intake on, but never ran it and I found this to be absolutely true.
Jeepguy's 360 before we began.
First thing we did was drain the coolant and removed the HEI distributor cap, wires, fuel hose, heater hose, thermostat housing, and upper radiator hose.
After that we removed the engine electrical wiring and sat it aside.
We then removed all of the intake manifold bolts using 9/16" wrenches and ratchet with swivel socket. The only trouble bolt was at the passenger side rear which was heavily rusted.
The value of not having a hood became apparent right away when Jeepguy went to lift the cast iron manifold off the engine and hand to me. He stood with one foot on the heater core housing and the other by the window washer bottle. He barely got it into my hands since he had to balance while lifting and moving 65 pounds of heaviness.
Once the manifold was off we checked for coolant in the lifter valley and were pleased that none had gotten in there.
We laid shop towels down over the cam and lifters and Jeepguy used a DA with 120 grit to remove rust, corrosion, carbon and old sealant from the heads and end rails.
Once the towels were removed, we then vacuumed the entire area, including intake and water crossover ports.
Here they are cleaning the head and rails to be sure all surfaces were clean. We then wiped everything down with a solvent based cleaner/degreaser.
At this point I we laid a thick bead of RTV along the front and rear block rails. We did not use the supplied rubber seals as they have proven to be leakers. We then sprayed Permatex Copper Plus on the intake ports, water passages and bottom side of the new metal valley tray gasket. I explained that the RTV would need to set up for some time before we put the new manifold on, and that the trick is to let it cure about 75% so that it must be pressed down upon by the manifold which would assure a good seal.
This is the new manifold. I cleaned the grey RTV from around the water ports and swapped the original valley baffle onto it. I used self tapping screws to fasten the baffle securely. I then shot the ports with copper plus and let it get tacky.
Jeepguy then placed the metal tray gasket into place and we verified that everything was lined up. I then directed Jeepguy to add a small amount of RTV to each corner where the head and block rail met.
Once we were satisfied that the RTV had set up properly Jeepguy got back into position and I handed the manifold to him. While he slowly lowered the manifold down into position, Max and I were ready with screwdrivers to align the bolt holes up once it was nearly down.
Once the manifold was in place, we installed the 4 center bolts and ran them down till about a 1/16" gap was left between the manifold and the washer. We let the manifold sit there for some time.
Once we let some time pass Jeepguy then installed the rest of the intake bolts to the same depth as the others.
Then, starting from the center and working out he brought all the bolts till each was lightly compressing the RTV end seals.
After letting some more time pass we went ahead and tightened all the bolts down and began putting everything back together.
One thing Jeepguy asked was about putting sealant on the bolts near the water crossovers. I told him that in 30 years of playing with AMC engines, I'd never had a leak issue in that area. Of course, I was wrong.
Here Jeepguy is finishing up the last details of the re-assembly.
Some of the issues we ran into were:
PCV grommet. (I robbed one from a 440 Dodge valve cover that fit perfectly)
Manifold vacuum fittings. (The rear one was VERY close to the carb, so I robbed another from my 401 and we installed it on the other available port)
Throttle linkage. (Using either set of holes didn't work well. (I bent the bracket backward enough to allow full throttle when the pedal hit the floor)
Oil filler tube. (His original tube refused to come out of the manifold so I robbed the chrome one off my 401)
We filled the engine with regular water and fired it up. When checking for leaks we found the heater hose and one manifold bolt had water leaking past the threads.
Here Jeepguy and his friend Max are pulling the intake bolt from the #2 intake port where there was a coolant leak.
We wrapped the threads with PTFE tape and re-installed it. No more leaks. Once we verified we had no leaks under pressure, we dropped the water out and filled the engine with fresh water for his drive home. I figure several fill and drains would get rid of a good amount of rust and corrosion that had built up. He said he would dump the water and fill with coolant the next day after another leak check.
We took our time and id this one carefully. Total time from start to finish 4 hours.
Jeepguy reported better throttle response and low end power with this swap.
I'll be doing the same swap soon and will add more photos to show each critical step in better detail.