With out a spark plug magnifying flashlight and the knowledge to translate what your seeing you really can not tell what's going on with your plugs heat range, nor your air to fuel ratio.
Due a on line search for the 5 page paper called Spark plug reading 101.
This paper is by Mike Canter.
There's no such thing as a Victor Jr for a Pontiac so are you posting about a SBC or some other non Pontiac motor?
You gave up 23% of the air flow you had with that 1050 to 850 swap, so I am not surprised that on a 600 hp motor you lost 6 mph from your ET.
Hook up a vacuum gauge that you can read during a run to the motor.
If then on a run you see 3/4" hg or higher showing up within 500 rpm of your shift point then that's telling you your 850 is too small.
The bottom line is this.
At peak Rev's if you get anything higher then a zero vacuum reading ,then YES at that point and ONLY then are your forcing the descending Pistons to try and make the added effort to suck air in and that's what you do not want in terms of producing the highest amount of peak Hp.
This once again this is in terms of and purely relating to peak hp and a slight vacuum reading can make for better torque production within your builds intended power band.
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs!
And he was not talking about 1/8 or 1/4 mile ETs!
1) 1940s 100% silver 4 cup tea server set.
Two dry rotted 14 x 10 Micky Thompson slicks.
1) un-mailed in gift coupon from a 1972 box of corn flakes.
Two pairs of brown leather flip flops, never seen more then 2 mph.
Education is what your left with once you forget things!
Last edited by steve25; 10-03-2023 at 06:17 AM.
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