Harbor city, CA
Elevation 49ft
CCP unspecified
transmission, unspecified
stall speed, unspecified
cruise-timing unspecified
IDK how anyone can give you accurate advice.
But yeah, as I said earlier, 67PMJs are gonna be really lean, requiring a lotta throttle to get to 65mph, and also possibly to maintain it.
Put some 70s in there and 78s in the back, and a 10.5 PV. Sync the Transfer ports, reset your pumps, Modify your VA and Mechanical Timing Curve to, together, generate at least 52* of Cruise timing.
Here's how to set your cruise timing exactly right.
1) check your timing at cruise-rpm
2) Set your cruise timing to 48*
3) rev your engine up to cruise rpm, and keep it there for the rest of this test.
4) without regard to the actual timing number, advance the timing a small amount. If the rpm goes up, bring it back to the reference rpm. Then repeat until additional timing produces no additional rpm.
5) but if additional timing from 48* does not produce additional rpm, then go the other way, taking out timing, looking for the max rpm at whatever timing.
6) after the max cruise timing is found; determine if the AFR is rich or lean, at that rpm and fix it.
7) finally, take out 3 degrees of advance, to compensate for the lack of cruise load. Read the timing; Whatever you get at cruise rpm, that is what your engine combo needs and wants, and that is your target.
8) reset your cruise-timing to what it was in step one above; then return the engine to idle and let it cool before shutting it off.
9) now you gotta figure out how to get to that target.
Notes.
1) what you are hunting for is the magic timing number required at cruise-rpm, at the smallest throttle opening, that the engine combo is able to produce. Then lean it out to the minimum amount of fuel to maintain that rpm, at that throttle opening.
This is so easy, and it works for any cruise-rpm.
2) I once had a combo that cruised 75@ 1840 rpm, in double-overdrive. I used this method, and she gave me back 32 mpgUSg. I'm certain that if I had been cruising in direct at 3300, the results would have been very different.
3) Another thing I did was to, at cruise rpm/speed, put the trans into neutral and see how much distance it took to slow down to about 20 mph.
Then I checked the cars mechanicals to see what could be done to increase this distance. Things like adjusting the wheelbearings , the brakes, installing new U-joints, adjusting the front-end height, the attack-angle of the rear spoiler, and of course, the tire pressures and the alignment.
4) I don't run that combo any more. That cam lost lobes, and I replaced it with the next bigger size from the same manufacturer. This new cam lost bottom-end, big-time, relatively speaking, leading to a different transmission, and the loss of Second overdrive.
The new combo cruises at 65=2240, and forget about 32mpgs. But it's still pretty good. But she now likes 56* or more, of cruize-timing. and I leaned her out a bit more, lol.