Originally Posted By: Mean buzzen half dozen A.K.A. Hank
Hmmm,,,, you were reading 13.something A/F ratio @ W.O.T.,,,, so yes it is & was still too lean @ W.O.T.
I guess I will need to reiterate myself, you need to be reading 11.8 A/F ratio or so (in the 11's) when you are running 15 PSI @ W.O.T. Low 13's (A/F ratio) is too lean!

Yes, the main jets are causing your A/F ratio @ idle is 10., but I believe there are ways to lean it out @ idle.
Your A/F ratio might be OK now w/you only running 6 psi or so.
We have not heard anything new if you had installed your new fuel pump & installed a boost ref line.
Last we heard, your going to install it, & you are only running 6 psi,, so what is the latest scenario of things that are on or off your engine, boost pressure running now? How much timing?
If you are running your new fuel pump & ref line & are running 15 psi & showing 13's A/F ratio still,,(too lean still) then you would need to go w/bigger main jets most likely, unless there are other ways to richen up your Holley for W.O.T blasts.
Turbo6 says not to drill out your idle jets,(dont drill just yet) but I believe that will lean out your idle (which you need) to a more fuel efficient A/F ratio in the 14's @ least.
Maybe turbo6 can tell you more how to mod your Holley more in detail step by step instruction?
I just know the basics & maybe a bit more, but I never blew through a Holley, just my DCOEs.
Your lean pop @ 13. A/F ratio is going to melt your pistons,,,, STOP DOING THAT!

I initially thought you could run approx 12 psi w/the stock fuel pump, but it seems going to 15 psi is OK according to other websites I have read.?? Research a bit more on that subject.

Make sure your float level is adjusted like turbo6 says, so the fuel is just dripping into the carb, meaning, your float bowl area is going to hold a bit more fuel (higher level than stock setting)
I thought Holley or another CO. made larger than stock float bowls?
I forgot, does your 2 bbl Holley have a plastic float?
If not, the brass one would have collasped by now. \:D

With the different Holley pump cams, there are white, orange, blue, etc in color & have different ramp rates, meaning depending on cam used, it can aggressively squirt a lot more initial fuel or less.

Catch us up to date,, when you first step on the gas,, what is the A/F ratio reading approx?
Black smoke, hesitant for the engine to accelerate, almost dies?

You need to let us know all the changes you do to your engine so we are up to date on things. ;\)

Goodluck, & when tuning, try to do one thing @ a time,,, try jetting, test drive,, change timing, test drive it, don't change timing, rejet, & accelrator squirt change all @ the same time.

MBHD


I'm not arguing with you that it is too lean? I'm just tell you what it is... I'm getting the jet kit on monday or tuesday and then I can start working with that and my power valve restriction sizes (to compensate for smaller jets which will give me that extra fuel at WOT). Then I can get those right. I'm not worried about what my A/F are as of right now because it's all going to change with the new smaller jets.

I'm not sure what the last you heard was. I never said I WAS running 6psi. I said I WANTED to run 6-8 psi. But the first time I installed the wastegate, it boosted to 15. I fixed it and it boosted to 3psi. Then I changed to springs to try to make it 6-8psi and it turned out to be 14psi :-(. But that's where it was the last time I wrote.

I have the new boost reffed pump on but I cannot check what it is in boost because it's an inline gauge so it's under my hood when I'm driving (and in boost). It also gives me a lean pop at full boost so it's either draining the bowls or the jets/power valves are still too small?? If I floor it while I'm driving, it'll keep pulling all the way til it hits boost, then pull really hard when it hits max boost and holds a 13 A/F then the A/Fs fly to LEAN after being in boost for a few seconds and I get off of it or it lean pops and then I get off of it. It doesn't die though?
Partial throttle like I said was bad because it lean popped and stumbled. It was fine if I went to full throttle and back off into partial throttle which is why I'm confident its just the timing of the accelerator pump.
Idle and cruise are still rich as all get out.

I don't know what the initial timing is at idle but I know with the vacuum advance, it's like 16. I'll have to check tomorrow. I just drove it and got into full boost in third gear and just waited for it to build boost and listened and if it knocked (or if I thought it knocked) at all, I just got off, adjusted timing, and tried again. I was pretty close because it only knocked a little bit so I just kept retarding it until it stopped.

I definitely don't have the brass or stock float. I specifically bought a nitrophyl float so it wouldn't crush under boost.

I still don't know why it's draining the bowls. I really just think the pump can't keep up even with the boost ref.

EDIT: could the stumble in boost maybe be spark blowout? I have them all gapped to .030"

Last edited by snowman4839; 10/30/11 02:11 AM.
69 Buick Special Deluxe. Intercooled Turbo Chevy 250 @ 15psi on a stock long block. It's kinda fast.