Can you unbolt the motor mounts from the frame brackets and jack the engine up? that may give you enough room to do the job. Remember to use never seize on the bolt threads. B.

 

Back in the 80's, a friend of mine had a 70 mach1 with the 428CJ. When he changed the plugs, he found it a whole lot easier to pull the motor up just enough to change them. You might find it easier just to pull the motor up just enough to get the manifolds on.

 

Much easier to install with exhaust manifolds already on the engine. Since the engine is already in I would either pull the engine or the heads and install the manifolds on to them. Very heavy to install the heads with manifolds but can be done. Edelbrocks will be easier. I tried installing the exhaust manifolds after the engine was in and gave up. Virtually impossible to reach the middle lower bolts with multiple extensions and knuckles and keep your sanity. Just about as fun as changing spark plugs..

 

i figured thats what we needed to do. looks like we will pluck the engine straight up by an intake manifold lift plate, bolt on the manifolds and set it back down. its just a rough install to assure the motor mounts were correct. on our first attempt we had to flip the rubber mounts on the block to make it sit correctly.

we discovered the car was a real S code a few years back with a marty report. when my mom bought the car from a shady car lot in the 70s they swapped out the entire drive train for a 289/c4/8'' setup. evidence that the car was a big block 4 speed was still there. after cleaning off the grime on the trans crossmember it was stamped 390, and the z bar mount was still attached to the frame. also the frame stands are original big block as well.

 

My 67 vert has similiar setup to what you're doing. When my orig 390 was rebuild, I too added Edlebrock aluminum hds and then found a set of orig SCJ exhaust manifolds. I chose to bolt manifolds with engine out (no 4spd until after). Then using engine leveler dropped engine in. Went fairly easy, I think easiest way, less headace.

 

The mounting height was different.

 

No, I'm getting away from this thread, I read the other thread and I seen what happens. See ya!!!

 

BTW I am sure you guys know but the 390 tranny x brace is the 69/70 250 brace!!

 

BTW one time I did a 428 CJ manifold install wth the short block in, but I bolted the manifolds to the heads and dropped each side on as a head and manifold assembly; that worked well.