Re: 750 DP to Holley HP Update
Swapped out main body to get rid of choke tower. Holley sends 76-82 jets, 31 squirter and 4.5 PV w/kit.
I swapped out to supplied jets, kept my 6.5 PV and kept my 40 squirters.
Made a 60.45 mile hwy trip with 4.3 gallons. 100*, engine temp pushing 180*, a little warm.
Plugs are black sooty. Going back to original 69-78ís as engine was dynoed with.
Made a test run. Now engine temp (w/leaner jetting cooled back to 175)
Iíve heard rich jetting will heat engine, never believed it. I do now !
Butt dyno does not record any increased HP w/new Holley HP main body, but IMO, worth the $125 to clean up under the hood and retro S/S look
What the butt dyno really liked is the Holley $35 progressive linkage delete. Instant HP 💪
383, M 21, 4:11 in 3500 # Chevy.
Nice looking setup !
I did this same swap of my DP body for an HP body to get air bleeds and choke horn delete. I have a wideband in my '70 SS396. The larger IFR (.033) in the Quick Fuel red DP upgrade metering blocks was perfect. It solved my tip-in stumble. For air bleeds, I started going big, then, ended loving the small -- HSAB - 25 to 31; LSAB - 68 to 72. This improves gas mileage. (Right now, I am debating between 27 and 31 for the LSAB, and settled on 68 for the LSAB). 68 LSAB will not lean out the IFR and give me plenty of transition gas for overdrive on the fwy - idle is at a perfect 14.2 for my cam, with approx 1 turn of the idle mixture screws. I also ended up with a larger PVR (larger than the stock .059 - I drilled the next size up), high flow power valve, and 9.5 rating even though I have a 292H Cam (high duration). This large PVR and quick opening PV allowed me to go to 72 on the front jets. Rear jets are around 83, 84. The smaller HSABs (25 to 31) will make everything richer on the top end and leaner in the mid-range, so, you need a good, quick opening PVR to avoid going lean in the mid-range. I also ended up with the blue cam on hole 2 for the front and the black cam (hole 1) for the rear. 31 nozzle with extensions in the front and 35 nozzle in the rear with extensions.
Note: This is my second HP body (AL) upgrade. I have one of the original zinc ones (2012?) with added quick fuel DP metering blocks and chrome bowls upgrade kit. This made my screws too short and after many, many, jet, IFR, emulsion changes, I ended up pulling out the threads on 2 screw holes in the zinc. So, now I have the 2-3/4" screws that I ground down to the perfect size for this new aluminum setup.
1970 Chevelle SS396 (408), Fathom Blue,
Original Block & Forged Crank, KB Pistons, Edelbrock 6045 Heads,Comp Cam 292H, March Serpentine, RPM AirGap,750HP,100hp Nitrous
A/F Wideband,Tremec TKO 600, 12 bolt,
30 spline Moser Axles, Richmond 3:73's, Hotchkis control arms, swaybars, springs, Wilwood 12" rotors D/S, 4 piston calipers
Last edited by hjdca; May 30th, 19 at 10:15 AM.