I would underline that if you are getting only 3 years out of ANY battery, let alone an Optima, (way over ten years in my Pan Americana Packard and just now starting to get a bit sluggish) then something else is wrong. What is your voltage across the terminals with the engine at a high idle? Do you use a trickle charger? Do you disconnect the battery when the car sits for long periods?

I regularly let cars sit for even 5 months without any sort of charge and then just get in and drive them away. Modern cars need trickle charging to deal with computer's drainage. Old cars do not.

There is no vacuum port available on the Rochester carb itself as that place is taken up by the big brass fitting that holds the check valve and the one line heading off to the wiper distribution manifold. Check your vacuum on that hard line as there is no restriction.

The vacuum port that goes to the vac advance should show essentially zero vacuum when the engine is idling as the carb is designed to shut it off.

I've had several cars in over the years where the idle was turned up enough that the vacuum advance was was activated. When the timing was then set to "spec"it was a VERY false reading as the vac advance was already "all in". That is why I strongly prefer to disconnect that vac advance line while setting the timing. The Rochesters are somewhat prone to this problem if the idle speed is a little high, the Carter 4bbl carbs even more so.

Your vacuum is still low. Have you ever checked the timing on this beast? Set the idle really slow and disconnect the vac advance line at the carb and then dial in 10 degrees.

Kev, you should be getting just a little less than manifold vacuum, and it should recover instantly when you push the pedal. I would not expect any less than 15 inches Hg. No wonder the brakes are terrible; you are getting no real assist.

Yes your hoses could be blocked or collapsed, but a likely culprit is the check valve. Of course, you can always test your manifold vacuum at the tube that comes out of the junction block between the carb and the check valve. I sure hope you have better than 5 inches there or you have a massive tuning problem to attend to.

Pull the vacuum line off the reserve tank under the fender and adapt a vacuum gage to it with a little hose. It would be good to know what sort of vac. you are getting in the system, especially during a brake application.

At this great age the check valve at the back at the carb can be acting as more of a pressure regulator than a check valve.

Oh, and I hate stainless steel lines.

Oh, and I do rebuild Tvacs.

Would just point out that unless some stunning new chemical miracle has transpired your new freshly painted manifold will turn brown at the crossover point in very short order if you drive the car at all.

Everything except the lockout cable is present. There is no reason to change anything til other evidence appears. Didn't someone reproduce those lockout cables? Otherwise any convenient remote control bowden cable could be substituted along with a little switch that would bear against the lockout lever.

It is comforting to see it is redlined at 3000.

Yes, I agree on the Grants. They have great oil control.

Some mission creepage is better than others. Those engines love a new set of rings and even Packard opined it was better sooner than later. Old rings worn thin start to do the hula in their grooves. After a while of that they break up into pieces and not so long after that migrate out the top of the piston so as to pay a visit to the valves. This is common long-stroke engine disease that I have seen in Packards Buicks, Chrysler products etc of that era. You are already buying a whole gasket set so pull those pistons out and have a look at the top rings and grooves especially. Plastigage the rod bearings before you yank them out. Look forward and poke the timing chain with a screwdriver and see its play. Or rock the crank back and forth and see how far you have to turn before the camshaft moves. Thunderbolts run cooler and stronger with a new chain.

I fully understand that you don't want to go that far but you have already undertaken quite a bit of the arduous work. For another 8 hours you can make the engine hold for another 40K miles or so.

A nice check on your valve work is pour a little thinner around them after assy and see if it stays put.