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No apparent header leaks. The PS header previously had 1/16" clearance from the upper A-frame mount. The thicker header gasket put the header in contact with it. I'll get a dent put in for clearance as part of the exhaust work.

Got the computer and its engine compartment harness out. That eliminates some of the messy wiring in the engine compartment and everything that was working seems to be still working.
Put a dent in the exhaust pipe where the shift lever was hitting. Exhaust pipes are tightened up almost in place. Sounds much better, although the mufflers are too loud, and even seems to run better. Its almost ready for a first drive and the trip to Henry's Muffler shop.

This is a picture of the firewall as viewed from under the passenger fender.
The new metal patch is where the computer wiring harness came thru the firewall. At the top center of the picture is a rectangular rubber flapper that apparently is an air check valve to let air out of the HVAC system into the engine compartment but not the other way. The flapper is deteriorated so it isn't normally closed and therefore not working.

Anyone know what that rubber thing is and what it's called? Didn't find anything about it in the Chevy shop manual. If I had a name for it I could look for a replacement.

If no replacement, would you seal it off or leave it as is? Don't like the idea of pulling air from the engine compartment into the cabin but I don't know if there would be some bad effect from sealing it. Haven't had a good idea for some make-shift replacement.

I would try to run the fan while under the car to see what happens with the flap. I would
also tape it closed and jam it open to see if air flow changes in the cabin. If you don't notice
much change, block it off. I can tell you from experience with the Vette that had a huge cam in
it.... engine compartment air in the cabin was not desirable.

GM

Roger that, GM. Thanks.

If I could think of something with a flat piece of flexible rubber, like an inner tube, I could make a new flapper. Ideas, anyone?

The flapper is apparently the drain for the AC evaporator. No known replacements. I put a metal screw in the corner that was sticking up and put the inner fender back in. Think it will be OK.

Next victim of the over tightening is the negative side post battery terminal. I noticed the negative terminal wasn't tight when it was removed. Its stripped out. The EC is ready for a road test if I can come up with a repair. Thinking maybe a few stands of copper wire in the threads might let the cable tighten up. The battery is only two years old but if that doesn't work it might have to be replaced.

I had an adapter from post battery to GM cable and the cable end was stripped out. I put a helicoil in it. Not sure if that would work for the battery but might be worth a shot.

Managed to get the cable snugged up. Think its good enough but I'll check it periodically to see if it stays put.

That's a really soft metal. You could probably drill and tap it at a later date to a larger size.

-BP

Drilling and tapping would work if I knew how much metal is there. Wouldn't want to hit acid. The battery is a little over 3 years old so if I can coax it thru a couple of years I'll feel it's near it's end of life and won't mind replacing it.

I have drilled and tapped successfully at work many many times.
I'd try it if the current repair doesn't work. At that point in time you
have nothing to lose.

GM

If I get to that point, maybe I'll hit you up for some advice on how to do it. Like, do you go to 7/16, the next bigger SAE, or maybe a metric in between 3/8 and 7/16? And, do you make the hole deeper or quit at the same depth?

This morning the passenger side header came off AGAIN and I got some clearance between the header/collector and the mount for the lower control arm. Massaged both the mount and the header. Put the header back on with the same aluminum gasket. Apparently they ARE reusable -- no obvious leaks.

With a coat hanger and some header wrap padding I got the exhaust system so its not rattling against the body, frame or X-member. Wednesday next week WXO and I will take it to Henry's to get the exhaust system renewed. Will DEFINITELY get some different mufflers. The ones on there are obnoxious.

Added 5 gal of 93 octane -- no movement in the gas gauge. Took it on a short drive around the neighborhood. Transmission works fine but its not running very well. With the engine warmed up the idle screws were adjusted again and it's idling not too bad but vacuum is only about 14 in Hg. Should call Blueprint and see what vacuum should be at idle. I'll install WXO's AFR meter and get it worked out.

Speedometer isn't working. Probably the cable isn't fully inserted in the head. Will check that and the ground for the gauges.

Got it cleaned up a little and the hood back on.
With an offset, drop air cleaner base the air cleaner with 3" filter fits under the hood. Phew!! I've been concerned about that since day 1 because of the taller Performer RPM intake. The air cleaner compresses the under-hood insulation some but it fits.

Its running well enough to get it to Henry's next week for the exhaust work. Next step will be to install WXO's AFR meter except for the O2 sensor which will get its bung next week.

(funny that the thumbnails are upside down but the expanded images are right side up.

Forgot to mention how much I like the Monte Carlo SS steering box. Play is gone and road feel is much improved with the 2.5 turns lock-to-lock. It surprised me at the first corner.

Contrary to the advice I got from BP tech support, I connected the vacuum advance. Idle probably picked up 4-500 RPM, smoothed out and vacuum picked up 2" Hg. With initial timing at 12*, I don't know why it needs so much more advance but it does. No kick back starting or shutting off. No spark knock. It now runs pretty good once it warms up. Good enough to start tuning the carb with the AFR meter.

Took it for a few miles on the Interstate then, on the way home, I smelled gasoline. Gotta give it one more check but I think the fuel pump https://www.summitracing.com/parts/sum-250020-1 started leaking at the lower of the two round gaskets. I need to check 'cause the other possibility is the Aviation Permatex, that's recommended for sealing gas fittings, dissolved and started leaking. If the fuel pump is leaking, I'll install the one that came with the El Camino temporarily. It has to be driveable on Wednesday when it gets the exhaust redone.