I installed my newly bought rebuilt Holley 500 cfm. Installed it. Ran fine through the warm up but then would idle very erratically. About every 5 secs it would idle up, then back down. Almost like someone pouring a little bit of gas down it's throat. I fixed that problem by opening up the throttle plate all the way. The choke had it closed 3/2 's of the way.
Now that she is idleing OK. As I take off, just as I ease the clutch out she will want to bog. I have to press in the clutch a little, give her a little gas, then we go. After I get moving, and my r's start to climb; just before my shirting point, I can feel the carb bog down. If I punch it to the floor she wakes right back up. But, I do not want to do that through every gear.
I didn't have this problem with my 2150, or I would think an intake leak of sorts. There are only three vac lines on this carb. One goes to the dist(spark port). One to the egr. The third has vac on it at idle and is plugged. I installed a brand new gasketk, that came with the carb. I bought it at a local carb shop.
I am totaly impressed with the power I have now. You can't compare the 500 to the 2150.

Help meeeeee.

Robert P.

 

have you tried adjusting your air/fuel mixture

 

I did play around with them last night. Didn't seem to be able to make a difference. I must do bills. So, after that I'll be outside to play with it again.

Robert P.

 

you might want to also check your float levels

 

Yes, I turned them out 1 1/2, 2, 2 1/2, and 3 turns. no difference. My timing is set at 12 btc. I am still having same problem.

side notes - If I turn the driver side idle/mix screw all the way in, it idles up to it's highest point. turning it out decreases the idle. the passenger side screw makes no difference to the motor, in or out.

Robert P.

 

if those answers didn't help then I'm not to sure and what I know is pretty limited so maybe someone else will be able to help.

 

Thanks for your help Karellen.
I believe I have solved some of the probs. I replace my power valve with a 4.5. Not sure what it had before but, it was a noticeabaly stronger spring. I replaced the #52 jets with #68. #68 are a bit to large so I will be going back to the parts house to get #62's.

I still can't get any adjustments out of either(now) of my air/fuel screws. All the way in, allthe way out. No change in rpm's or vac.

Oh, float level is right on. Is was off though, so thanks again for the thought.

Robert P.

 

Remove both those screws and blow a couple of shots of carb cleaner through them with the red wand.
It seems like at least one is blocked.

 

I ment to state it in my last post. I pulled the carb apart to install the new power valve and jets. At that time I did spray out the one in question, and saw a piece of something come out. ( I suspect a piece of the packing around the needle.) But, in any case. All problems solved except the fact that the screws will not adjust.
Not sure what effect this will have on my motor?
But it is running excelllllent. No stutter on take off and no bogging on acceleration. It doesn't seem to be running rich either. At least the fuel smell has gone away, from what I noticed with the 2150.
Kudos to Holley and their 500cfm 2 barrel carb. Why Ford didn't install this baby for OEM, I have no idea.

Anybody out there with the stock 2b, I recommend getting and installing the 500. I replaced the jets with #62 and the power valve with a 10. Works remarkably well, compared to stock.

Robert P.

 

If you get the throttle blades too far open at idle the mixture screws will cease to be effective. They are after all idle mixture adjustment.

 

I read that somewhere else also. But, I am at a lose as how to bring it down anymore. It is timed where it should be, She is idleing where she should be. When the choke is off the plates are fully open.
I did read somewhere that a larger hole in the throttle plates would cause more air, thus bring the mototr r's down, thus causing one to have to close the t-plates to balance out the fuel air mix. I'm not sure of this procedure though. Will have to do some calling.

Robert P.

 

At the first sign of trouble I would have taken it back to the carb shop.
I hope that you save all of your reciepts and take them to the carb shop and ask for a reimbursment.

----Patrick

 

I appreciate the thought. But, to think of going back to the original carb again, is out of the question. Besides this is where the unknowing gain knowledge. I'll figure it out eventuallly. She's not going anywhere any time soon.

Thanks, Robert P.

 

A few yrs ago, I installed a Holley 500 cfm carb on my 390 also. Woke that truck right up! If you are having bogging probs check the accelerator pump and cam on linkage. See if has a 30cc or 50cc pump on it. Most had the 50cc pump on when new. My stock car bud has to run one on his Sportsmans class car. I gave him my 500 cfm when I changed to a 600cfm 4bbl. (legal on a '72 390) when I dropped rebuild in.

 

Although I have rebuilt many carbs myself over the yrs, I have a couple of times bought a rebuilt carb at different stores. One time I had to return 2 carbs to the store before I got one that worked. They can be wore out (metal clearances) and carb kits won't fix the prob. When you can buy a brand new Holley 500 for 200 bucks, don't even think about a rebuild. (Jegs)