I ran un ported 96s on a .060 over 1970 455 and got down to 12.07 @109 MPH.
A Holley 3310 style vacuum secondary carb is a fine carburetor. I got down to 12.30 with one and won many races with it on my 455. 12.07 was with a 850 DP. As long as it is a duel feed type and a jet plate in the secondary you are good. A light spring and the right jets and you are fine. They are tunable and come on the sort of rich side but I will not get into leaning one out for power.
A "Performer" should not be on any 455. They are a good intake for a Pontiac 350, that' about it.
RPM is better. Myself, I like single plane intakes for a 455. They have enough grunt you will not miss anything and the boost on top end is worth it, as long as you have a good cam.
I like those cheap Tomahawk intakes designed after a fully ported HSD. I got down to 11 flat with one.
The cam, its too small. The rule of thumb on a street performance Pontiac 455 is 230ish intake duration @ .050. 455s are voracious and can take a lot of cam and carb.
I ran high 12s with a .230 Erson cam, the 12.07 was with a Crower sft in the .250s @.050, 108. Pretty lumpy for the street.
Now you run a decent fuel pump, but have you taken off the sock off the pickup in the tank ? I took mine off and put a short piece of hose on it.
The chain ? If it really does have some slop when new a short chain is in order. Now normally I am all in on the Cloyes, but their short chain was not a IWIS. Rollermaster has gotten a bad rap by some, and deservedly so IMO. BUT..... they now sell a .005 short chain that is IWIS AND has nitrided sprockets AND......................a big AND here is a Torrington bearing for only 165.72 $
Like half the price of a Sims. This is now the best Pontiac roller chain on the market. But some street guys might not like the little roller bearings in there, I get it.
My current engine has billet caps so its been aligned bored. Thing was, a simple, basic Elgin 3/4" wide Morse chain was a little tighter than the .005 short chain so that is what is on it right now. You can get those for like 30-40 $. Cloyes does sell a 32$ version of that chain, I have one but it was on the lose side so its still in the box.
I have a extra RPM intake I can part with if interested, used only one season.
Keep at it, you have a lot more power in your 455. Just go get it.
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