Holley 750 double pumper question

[honcho]

My 440 is sick and it's lookin like its the carb. Going to change spark plugs first to see what is going on with the carb. Carb is about 4 yrs old with a 50 cc race kit in it. I have done inspection on carb,floats are set correctly,fuel psi is correct,the only thing I can see not right is the accelerator pump is not set to Holley specs. The previous owner had this set up put on at a speed shop. So I really feel like the carb has trash in it,so going to put a kit in it,how important is the accelerator pump specs?? It has been running fine since I have had it but she is sick now. I am not a carb guy,so going to wing this and hope she will run. Any encouragement and advice greatly sought after and thanks Todd

[67440Dodge]

Before we go recommending, what exactly is the carb doing?

[honcho]

We are surging really bad and it won't stay ideling at stop. At higher rpm's you don't feel it,it's starving for fuel in my opinion. This problem just came up within the last 2 weeks,prior to this,we could smoke some tires

[4264door]

Have you checked for vacuum leaks? Is the carb tight to the gasket? Is the throat of the carb looking like it needs cleaning? We'll get to the bottom of this but we need more input. What kind of choke is installed, manual, vacuum or electric? I love carburetor problems, it usually entails a complete tear-down and rebuild and my jeans and t-shirt stink like gas but....I love it! Another huge thing to check out is if the throttle shaft is worn in its' bores and losing vacuum at idle. My hemi did that on the rear carb and I had to have the bores rebushed and , what a difference it made on idle speed and smoothness and got rid of the bogging totally. Which manifold are you using? Your accelerator pump is very important to the function of the carb. 50cc pumps are a lot of fuel for a street engine and if the accelerator pump is faulty then you will not get enough fuel to keep those pumps working the way they were meant to. Sounds like you have a race carb being used on the street. I assume your car is a street driver? If it is, I would have to say in my experience that is way too much carb, especially if you are running a stock automatic transmission with highway gears. Do you know which size jets are in the carb? A high geared 4-speed LOVES big 50cc pumps, as does an automatic with a high stall convertor with tall rear gears. Sounds like your fuel pump is working fine. Let us know what the plugs look like when you pull them out. Other things can crop up too than would point to another problem in the engine, usually a valve sealing issue. You need to perform a vacuum check on the engine and a leak down test would also help find a leakage problem.

[ws27]

Go through the ignition system before you go through the carb.

[67440Dodge]

If this came on suddenly, I'd replace the power valve. Make sure you get the same rated one, otherwise you'll be chasing your tail..

[honcho]

Thanks,no vacum leaks,727 tranney,shift kit,stall converter,323 in the rear, you can have lunch on my motor. 426 you da man,thanks so much for your info. This motor has a purple very radical cam in her,original set up with 2-4's,previous owner yanked them off and put the 750 on,said car was too much on the street. I am gonna take plugs out and go from there. Never rebuilt Holley before but they are pretty simple. Stock rebuild kit will not come with 50cc accelerator pump,but will order one. The accelerator pump is not to Holley specs,when I rebuild,should I go to Holley specs or leave the adjustment where it is at??? It has ran fine since I have had her but the accelerator pump is my concern,damn this gonna be a good learning experience for me

[Ledsled 75]

I agree with 67440Dodge, I would get a new power valve. Also would replace the front and rear accel. pumps, you can go to holley.com and put in your carb#, you can print rebuild sheets, schematics and etc. They make it super easy for you! If you get stuck you can call holley, they will help you with anything. They're great,good luck.

[honcho]

Yea thanks guys,I went to Holley website and could not find a phone # Yea also looking at changing out fuel nozzles,I have 28 in now,Holly says go 3 numbers up or down and see if there is a difference,gonna experiment and go from there,my Coronet does not give up remedies very easily,she hates being messed with,it's a ass wupin to work on her

[honcho]

Update!!!!!! Man I found ths guy who builds race engines and also makes custom rifles. Has his own gun range and machine shop. Builds engines and rifles from scratch. He first set air/fuel settings by ear,not by vacum gauge. Disconnect vacum advance,adjusted accel. pump,bumped timing up just a little. Runs like it has never run before. Will taking it back to him next week so he can pull dist. and adjust stuff from inside. Very old school ,but you can't find guys like this anymore,he is out in the woods,no sign,no markings of any kind you would know what he does,charged me 50.00. He is my hero