Those older Holley's were setup factory to run on mildly warmed over engines. I would rather run one just a little rich especially today I may be wrong but I would rather err in that direction. I sold it in 1973 saw it again in 75 the engine was still Later I put just a little stouter crane cam in it nothing ridiculous, up graded the rockers and push rod made few minor improvements to the engine I drove it another 40,000 miles on the street. Never did have any tune issues with it and it was just a great running motor pure stock. The stock Chevy cam ran really nice with 375 hoss's and 4.11 gears on the street 2nd gear take off worked great. a E-5 in the AF didn't make enough back them to blow up much. Didn't do a lot of strip running with it.

Could have easily gone up 2 to 4 jets sizes on each side. For sure with the lighter jetting I was leaving probably 20-30 hp. It was jetted for street use paper bag color just a teence darker on the street. I did have the rectangular intakes, domed pistons for 11 to 1. I did put a little better Edelbrock intake on it and staggered the jets which I think at the time was the suggested setup.

I set the lifters maybe every 4 or 6 thousand miles rarely would there be more than a thousandths difference either way on any lifter. We did have 105 octane back then which made them run and idle a WHOLE lot better. It had the 3310 Holley I think I actually set the float level once in 3 years. Lee back in the day I had an absolutely stock 1968 / L78 375 396.

Whatsize power valve stock 1850 holley