Calling all Holley guys!

[HP_Cuda]

Your fuel pressure guage is liquid filled yes? Then you have heat issues under the hood and they are known to drop. To fix this problem get a fuel guage which is NOT liquid filled= problem solved.

A normal 750 double pumper has jets like 72(Fronts) 84 (Rear) so if you have 73's all around then you are starving your secondaries which is why you run lean at WOT. Pull the carb and verify the jets and squirter sizes, while you are at it, change out the power valve based on your idle vacuum.

Don't worry about the accelerator pump as that is for off idle and is not your issue right now. You have a WOT issue - stick with that.

[734406pk]

Get yourself a mechanical fuel pressure gauge and attatch it to the hood using some zip ties and padding. Connect it to the FPR and go for a test run. Having a passenger record the AFR, fuel pressure, vac, rpm etc is very helpful and much safer since you can concentrate on driving. Take note of when the lean condition occurs ie full power acceleration or steady state secondary etc. Basically  a dyno run in motion. Drive safely!

[msbaugh]

Wow, alot of great responses... thank you everyone for your advice.  I will run a few tests and post back my results, fuel starvation rather than a carburetor problem seems more and more likely after seeing your responses.  I did have much higher jets in the secondaries for testing and saw 0 change on the wideband so this makes sense.

-Bought a new aermotive gauge (they make a durable liquid filled gauge now with a pressure relief valve you can pull with your finger to equalize pressure in the gauge.  Should take care of lower readings from high under hood temperatures). 
-Bought a 6 foot -04 an fuel gauge line that I'll strap to my hood for testing.  This will verify a drop in pressure under WOT
-Will check fuel filters and leave carb in stock holley set up (as stated above) for testing

[cudabob496]

Wow, alot of great responses... thank you everyone for your advice.  I will run a few tests and post back my results, fuel starvation rather than a carburetor problem seems more and more likely after seeing your responses.  I did have much higher jets in the secondaries for testing and saw 0 change on the wideband so this makes sense.

-Bought a new aermotive gauge (they make a durable liquid filled gauge now with a pressure relief valve you can pull with your finger to equalize pressure in the gauge.  Should take care of lower readings from high under hood temperatures). 
-Bought a 6 foot -04 an fuel gauge line that I'll strap to my hood for testing.  This will verify a drop in pressure under WOT
-Will check fuel filters and leave carb in stock holley set up (as stated above) for testing

I have an electric fuel pressure gauge inside car. Much easier to install/use.

[734406pk]

I have an electric fuel pressure gauge inside car. Much easier to install/use.

That's a great idea for a permanent installation. Also worth mentioning is Holley carbs usually have small filters installed behind the inlet fittings of the float bowls. Restricted filter(s) here won't show on the fuel pressure gauge. I would just change them to be sure or some people remove them permanently and use an inline external filter.

[cudabob496]

That's a great idea for a permanent installation. Also worth mentioning is Holley carbs usually have small filters installed behind the inlet fittings of the float bowls. Restricted filter(s) here won't show on the fuel pressure gauge. I would just change them to be sure or some people remove them permanently and use an inline external filter.

ya, I removed them, to get my pressure around 6.5 to 7 psi.
Only need one filter.

this year my fuel pressure dropped to 5 psi, from 6.5. Replacing filter solved that. As I've said before,
the more gauges, the quicker you diagnose small problems, before they become big.
AFR meter is another great tool.  It detects the smallest changes.ie, was running around 14.5, instead
of 13.5.  Found out air filter base was not secured properly to carburetor.

[734406pk]

ya, I removed them, to get my pressure around 6.5 to 7 psi.
Only need one filter.

this year my fuel pressure dropped to 5 psi, from 6.5. Replacing filter solved that. As I've said before,
the more gauges, the quicker you diagnose small problems, before they become big.
AFR meter is another great tool.  It detects the smallest changes.ie, was running around 14.5, instead
of 13.5.  Found out air filter base was not secured properly to carburetor.

Yep, knowledge is power! The AFR gauge is incredibly sensitive. It is too easy to over correct. Atmospheric presure, humidity, air temp and many other factors will effect the air fuel ratio. But one thing that is a definite is when it detects a lean condition, it's correct and you will feel it stumble/ hesitate. On the rich side, the engine will just consume the fuel and maybe foul plugs, but seams to run ok. 13.5 AFR at steady cruise should be safe and has some leeway for climate changes. 15.0 and above is trouble waiting to happen.

[msbaugh]

Well I definately have trouble waiting to happen because it's lean as hell on WOT. I have only one filter and its near the back of the car... right after the tank. The rest is plumbed running the passenger side. I will change the filter

And I'll have lots of gauges to read when testing next time. I don't plan on leaving the wideband or fuel pressure in permanently though.  They will at least point me in the right direction.

[msbaugh]

On a side note would it be beneficial to run a 3/4 closed needle valve or a snubber before the gauge. That's what the cummins guys use to delay pressure spikes from big injection pumps. Might help with the normal fluctuation of a mechanical pump

[734406pk]

Yes use a snubber or valve to dampen pressure spike from the mech pump. A snubber is cheap and can be had from mcmaster Carr. That's what I use and I'm a Cummins Guy too! Gauges whether permanent or temp are just a personal preference. Also a manifold vacuum gauge will be a major plus when tuning your Holley carb. When you feel or see a fuel issue, make note of all readings and you will be able to quickly dial in your carb. Good luck and keep us posted!

[msbaugh]

Well.. took a while to get my gauge in. Got it hooked up to the port on the dual feed fuel line and 6ft of hose zip tied to my windshield wiper so I can see inside the cab.

I changed the fuel filter as well. It definately had a little bit of restriction. Got a steady 6 psi at idle now and when I hit the throttle in park it doesn't drop. Once the monsoon quits here in LA I'll make my test drive and hopefully get back to tuning again.

I was scared I had a kink when I bent the S.S. lines for the car, lbut that was a while ago. Let's hope not because that was hard work!!

[cudabob496]

Well.. took a while to get my gauge in. Got it hooked up to the port on the dual feed fuel line and 6ft of hose zip tied to my windshield wiper so I can see inside the cab.

I changed the fuel filter as well. It definately had a little bit of restriction. Got a steady 6 psi at idle now and when I hit the throttle in park it doesn't drop. Once the monsoon quits here in LA I'll make my test drive and hopefully get back to tuning again.

I was scared I had a kink when I bent the S.S. lines for the car, lbut that was a while ago. Let's hope not because that was hard work!!

6psi is great! My pressure recently dropped to 5, and it was the fuel filter that needed replacement.

[734406pk]

Good luck on your test run, hopefully the fuel pressure will hold steady at full demand!

[msbaugh]

Well I'm having a headache right now! Note to everyone! DO NOT USE CLEAR FLOAT BOWL SIGHT PLUGS.  Both of mine melted with one 5 minute drive and fused plastic to the threads on my float bowls. Fused to the point that no fuel could get out. I hope I didn't clog a bunch of **** up now. What pieces of crap!!

[cudabob496]

I have Holley site glasses. They haven't melted, but I don't use
ethanol gas either.

There are glass site glasses on the market.