For a Big Block street/strip, bracket car, N/A, pump gas, single four

After you maximized jetting with a dual plane intake

Then swapped to a single plane, change nothing else

Did you have adjust jetting to maximize the combination again with the single plane ?

Almost any change be it exhaust, vert intake etc needs some tweaks..........some easier than others.........

All eight spark plugs

Just by the nature of the design, " two planes" in which the air is trying to mix, " in halves" verus " one bigger" plane, simply cant mix the same, just as each port in any design is often different to match. EGT and O2 sensors are your friend.


With the amount of nitrous your planning on spraying, it wont even matter!

Father, you have your answer!

Hell.. just air temps can make you change jetting

I have changed the jets, all eight of them, in my old 440 M.W. Bracket car from late morning to mid afternoon at the old LACR track in August when the B.P. dropped three inches, the humidity increased 35 %, the air temps increased 25 F and the density altitude went up 6500 Ft., from 4500 D.A. to 11,000 DA

Generally the vacuum loss (much larger plenum volume) needs more fuel.
Exhaust re-breathing with big overlap becomes worse; idle quality goes down; stall speed with the same converter is down.
Primary PV may need to be lower.
Sometimes +5 degrees initial lead helps (deduct from the curve for the same total).