Equal length headers to 340 manifolds. Re jet carb?

[1968FormulaS340]

Title says it all. I think I am running a bit fat now. Where would you start? 2 sizes down or more?

I now have 76 fr, 74 rear in a Holley 800DP. I also have a Holley 750 vs and the org 625? AVS to play with. The AVS is to small.

68 340, ported and flowed X heads, 11.7cr, Crower solid street roller, 4 speed, 3.91 rear.

Best time with slicks, headers and 3" exhaust 11.78 @ 118, best time with manifolds, 2.5" exhaust and E70-14 Redlines 13.2 @ 105

 

[rumblefish360]

larger jets, 2 steps each try until performance falls off or the machine sez OK.

 

[1968FormulaS340]

Larger? Im running rich now.

 

[388dart]

If you have a power valve in the primary side, then change the sec. jets to 82s and see what the diff. is or go 74 prim and 82 sec. If no power valve then go up 2 sizes on all 4 corners and see what happens.

 

[1968FormulaS340]

I have a power valve on both sides. I must not be getting something here. I removed the headers and now run manifolds. Car is a bit rich, wouldn't I want smaller jets?

 

[1968FormulaS340]

If you have a power valve in the primary side, then change the sec. jets to 82s and see what the diff. is or go 74 prim and 82 sec. If no power valve then go up 2 sizes on all 4 corners and see what happens.

Ok I see. You are suggesting smaller on the primary side and larger on the secondary.

LOL sometimes Im a bit slow.

 

[rumblefish360]

This;

Best time with slicks, headers and 3" exhaust 11.78 @ 118, best time with manifolds, 2.5" exhaust and E70-14 Redlines 13.2 @ 105

Lead me to believe you went from manifolds to headers which would, of course cause a lean condition.
Of course, the title sez differently. Duh on me.
Do you have an air/fuel gauge on hand?