jaybuller

Plugs are in order from left to right. All the way right is #1 and #2
hello I've got an lq9 with hand ported 243 heads compression is 11:1.1 or so. and a holley single plane intake and a pro systems 780 carb. And. A tick stage 2 cam. Running tr6 plugs 038 gapped

My issue is the front two plugs (#1 and #2 ) are lean and the rest are pig rich. Soot all over the rest and the first two plugs are tan like they should be. What do I need to be looking for? I've checked for intake leaks and there is none. The car runs like a raped ape running 7.0 in the 1/8 in a 3300 pound cutlass with a powerglide. But checking the plugs I really want to get all the cly evenly right.
Many sugestions are welcome. I'll try and post a picture of the plugs. (The plugs are from running around with some idling too not just a wot run and shutoff)

jaybuller

This is the intake setup

LQ4BU

If you do not have access to an air/fuel meter, I would probably drive around awhile at normal speeds, with new plugs, and see how they look. You should also have some plugs to use at the track, so you can see how those look after a run. You have to separate "driving around" from "wot" so you can see what is causing the plugs to look like that.



Do you know what the jetting is in the front and rear of the carb?

Did Pro Systems build the carb for you or did you buy it off someone?

jaybuller

Yes pro systems built the carb for me. The only thing I've done is changed the idle air bleeds from .075s all around to .080s and adjust the 4 corner idle screws. It was way rich with the .075 bleeds and I could not adjust it out with the screws. Now I've got the .085 bleeds in it and all 4 corner screws at 1 1/2 turn out and it's pretty clean idle.

Doug G

1.5 turns out on the IAB screws is not set in stone.....Mine are 3/4ish turn out and fine.

BUT, by "clean". How are you checking that ? ........nose....eyes ? lol

jaybuller

Hahha yes eyes and nose. Still stinging slightly but no visual "rich smoke" when I've got the screws in any less than 1 1/4 turn I have a hesitation so I compromise and go a little fat on the idle circuit to keep the snappy throttle. Yeah yeah I know I really need to get a wideband!

Doug G

AFR gauge is the BEST thing I did in my carb tuning history.

Make adjustment and see now....no plug reading needed

jaybuller

Yeah soon..... but my biggest issue right now is why is my front two cly so much leaner than the other 6? It's to a degree that if I make the other 6 cly right the front two will be too hot and hurt somthing

dogsballs

No fuel leaks in carb?

Fuel pushing past needle and seat

jaybuller

No fuel leaks that I can see. I can lean it out at idle by screwing in the mixture screws to about 3/4 from all in but then it hesitates off idle so I keep them out about 1 1/2 turns. But my issue is that the front 2 cly are lean and the rest are fat. I'm just trying to figure out why those front 2 are lean. I know why the rest are fat... just can't figure out why the front 2 are different

LQ4BU

If I was you, I would call Pro Systems and see what they say. They offer customer service for customers, and they have a forum on their site as well.

Doug G

I would check for any vacuum leaks, check those 2 coils, wires, and maybe even check those 2 exhaust pipes temps Vs the other 6 ?

For a start.

Pop N Wood

iTrader: (1)

I would bite the bullet and get a wideband, re-tune than revisit the problem once you know you have all the different circuits right.

Changing idle air bleeds without touching the idle feed restrictors could make it go way lean prior to transitioning to the mains. A wideband will tell you that in one drive.

For grins try flipping the carb around backwards and see if the lean plugs move to the back.

Bowtiedford

iTrader: (9)

the Holley intakes from what we have seen are sometimes prone to vacuum leaks. I know mine did till I went to paper gaskets. and we couldnt find it but tried to gaskets and all good. as said call Pro Systems, the are real good and keep it all on file. you will need their build number. mine was awesome right out of the box. just had to adjust the secondaries opening a little