edski,
It sounds like you had not used an Offy intake?
Just want to make sure,because I think if I had only used a Clifford intake & never used an Offy for comparision,I most likely would had said the same.
I to never had cold weather problems w/either intakes here in So-Cal.
I will also add,when me & a friend first started putting together his 250 L6,he had used an Offy intake manifold,Clifford headers ect,into a 69 Camaro(which I own today)
The Camaro had 3.08 rear gears,saganaw 3 speed on the floor.Carter 500 CFM carb,large chamber head, stock valves, standard valve job,stock type .030" over pistons,cam was american cam. .510 lift 280 advertized duration 110 lobe center.
It ran OK,high 15' low 16's in the 1/4 mile.
One day I had a neighbor selling a Clifford intake w/a Holley 2bbl carb 350 CFM,picked it up for $20.00.
I was really excited about the price I got it for & could not wait to put it on & try it out.
I used the same carb 500 CFM,,well,to tell you it did not run that well down low would be an understatement.
I swapped jetting metering rods,bought the Carter complete jet kit,swapped springs & so-on. Installed 4 hole spacers,open spacers,2" 1" you name it.
I also used/tried Holley 600 CFM vac carb,Quadrajets,Thermaquad,Carter AFB/s AVS" 400,500 -625 CFM (friends had Mopars) Rochester small & large 2bbl carbs.
All this work & I was very disappointed.
Even tried the 350 CFM 2 BBL Holley,that helped the low end response,but the top end pull suffered.
W/the Clifford intake & all the 4 bbl carbs I tried ,it did not carburate as well as they did w/the Offy.
Raced against a friends car,& my Camaro was indeed slower & you could definately feel it.
Put the Offy back on,better throttle response,raced against same friends car & it was back to being even as before.(thats' the main reason I wanted to put on a higher performance intake manifold than the Offy,I wanted to pull away from my friends 69 Firebird 400 CI Pontiac(weighed 3700+ lbs no driver) ,we were always dead even w/the Offy),put the Clifford on, back to loosing too much power again.
I then realized, I would need to do more drastic measures if I were to beat my friends 400 Poncho.
I got 4.10 posi rear end,TH350 trans, 3500 stall converter,actually only stalled to 2700,then @ that point I used the Clifford intake(made more mid to top end power than the Offy)
Fianally ,got faster out of the hole & I could hold him off on the top end.
It was not tell much later I installed 3 Side draft DCOE Webers & Clifford intake,which was the ultimate power maker. Everywhere, in all RPMs it made more power period!
Hope I didn't bore you.
MBHD