Carbureted LSX forum - Advice on baseline tune

Last year I had my car dyno tuned, didn't finish though as a driveline problem occured. Tune was most of the way there and I was running an 800 Holley DP that could not lean it out.

This year I swapped back to my 750 Vac seconday Holley.

Current Setup:
Chevelle (~3600 lbs)
200-4r tranny 2500 stall
4.10 gears
6.0 LQ4
243 Heads (Corvette)
Cam: Intake 230, Exh 237, .540 lift, 110 LSA
Carb:
1 turn out on idle mix screws
6.5 power valve
stock secondary spring
Front Jets: 72 (IIRC)
Rear Jets: 74 (IIRC)
Timing:
11 degrees @ 0
ramped to 18 @ 1000
ramped to 24 @ 2000
ramped to 28 @ 4000 through the rest of the curve
MAP:
10 @ 0 to 6
ramped down to 0 @ 12 through the rest of the curve


My problems:

1) It will idle around 700 in gear, but it shoots to 1200 RPM in park. If I shut it off with the high idle, it diesels bad. Any advice? I was assuming timing?

2) It seems real rich at idle, but I am only running 1 turn out on the screws. What is everyone else running for idle mixture?

3) How do the carb settings look compared to what everyone else is running? I only ask becasue it seems to like drinking the gas (compared to when I previously ran this carb) and a little sluggish (no stumble though).

Thanks for any input.

What intake are you running, single or dual plane?

Idle circuits on old school Holleys with single plane intakes tend to run really rich unless you have done something about it. My idle screws are at a half turn right now. The newer HP and street avenger carbs seem to do better right out of the box than the standard double pumpers.

Best advice I can give is to get a wideband.

Until then go to the Holley websight and look up the tech article that describes how to adjust the idle screws using a vacuum gauge.

Dual Plane.

I always spend all summer dealing with finicky carbs and burning $+4/gal gas. I'm looking into the fast ez-efi.

What octane fuel? A wide band will help, but with ls6 castings, compression is a no go for 87 octane and will diesel down like that, my lq4 with stock 317s shaved a bit will do the same on 87 so I run 89, and you have more compression than I do. Your timing seems pretty low as well, I run 20* initial and 35 all in by 2000, try rolling into 320 by 2500 and see how it does, check plugs for now since no wide band.

Dual planes are suppose to be easier to tune. They don't have the off idle bog like single planes.

You need to do a little more than just setting the idle screws at 1 turn. I hear you about wanting to go the fast EFI route, those seem to work really well. But I would think 20 minutes with a vaccum gauge would be time well spent. Hell, you don't even need a vac gauge, just hook a laptop to the MSD box and read the vacuum there. It can take some time to get the carb set right initially but once you do it won't take a lot of tinkering with.

Good luck either way.

I am running premium (91 octane). I priced out an FI system and sorry to say it, but the carb is coming off. I have had a few good carbs in the past (Idle, fuel bowls, jets, pumps, done!). The last few have been on my S*&t list.

let us know how the EFI works out, I assume your going with the FAST EZ EFI?

let us know how the EFI works out, I assume your going with the FAST EZ EFI?

Truck Intake with Holley HP EFI. Ill probably comment on the forum either way. Carb intake and ign. box isn't even off the car and it's already sold.