Holley 350 load problem...need help please!!!

[Falcon Ranch]

OK, I'll try to keep it short...after many jet changes, I went back to stock 55 mains that came with the carb...I drove the truck to work 1 1/2 miles away for 2 weeks which is not for enough to reach to full temp...the truck ran great the whole time...after 6 weeks of sitting I drove it down the street to keep fluids moving and such...it started off OK until is shifted into 2nd gear which it started loading up on me which it hasn't done before it sat...I followed my brother who drove it home for me yesterday and noticed small amounts of black smoke would puff out every once in a while, not heavy but enough that you can just see it puff out...so it has little power while trying to accelerate...but once at a steady speed it would sort of catch up and run smoother...I did try a smaller power valve which was a 4.5 but it had little power when the pedal was pressed, so I went back to the stock 8.5pv which helped a lot...I know if I clean the plugs which are pretty black right know it will run fine again for a while until the plugs fouled out again...my question is without having a O2 reader, I know the plugs should be a golden brown correct?... I was thinking of installing some #50 or #52 main jets but wanted to ask for your advise first...they say never to jump more then 2 sizes at a time but this has cost me a tone of money in small parts already.

I have 17 inches of vacuum at idle @800rpm...the mixture screws are set at 1.5 turns right now and am running a 260H cam...the engine will start right up after warmed up without touching the pedal, so I know I'm close to the right jet size but would like to hear from someone who has done this already and what size jets works for them.

I just want to get this thing tuned to the point that I don't have to keep cleaning plugs all the time, which this is my 3rd set of plugs...I just want it fixed right...I have a stock carb that I used to compare the bore size with and the Holley is like 2 carbs bolted on...my stock Holley 1 bbl was running a #56 main jet but since I have so many performance stuff bolted on, going half the jet size for double the breathing makes no sense to me...so what do you guys suggest I should do?

Jets sizes tried so far:
#67, #65, #63, #60, #57's...and finally back to stock...I started off high as it was recommended by a friend of mine...I tried the Holler equation for a PV size but it seemed to run my engine a little on the lean side while accelerating...I may try a 7.5pv but not sure it will make much difference then the 8.5 I have now.

I just wish there was a freak 'n chart that had a cubic inch displacement that had a cfm flow chart for recommended jet and PV sizes.

Frustrated

 

[wsa111]

Frustrated, check your choke, if manual is it open after engine warmup or if is an electric choke is it fully open during warmup??

On my engine where the carb is direct mounted to the intake, i run 59 or 60 main jets, 8.5 power valve & adjust the idle mixture screws to the highest vacuum reading & or rpm & then lean the screws to obtain a 10-20 rpm drop.

You might want to replace your float to a brass one & make sure it has the spring attached to the float to aid in closing.

I use brasswell road race floats & also duracron floats with better success.

Replace the needle and seat with a new on, & coat the o'ring seal with vasoline during installation to prevent cutting the rubber o'ring & make sure you have the float set properly.

Make sure your fuel pressure is under 8#

If you have an adapter to the original one barrel intake, your jet size may be ok. Bill

 

[Falcon Ranch]

Bill, thanks for the reply...the float in my carb is brass I believe, I've had the cover off so many times I'm pretty sure it is brass...the carb has maybe 250 miles on it as it is new out of the box...I will clean the plugs and readjust everything like I did before...I did use a vacuum gauge to adjust my timing...maybe I need to turn the mixture screws in a little more, I remember when I adjusted the screw, I turned it slowly until it wanted to stall out then back it out a quarter turn...as for the choke it is a manual set-up but I always make sure it is fully open...the pressure regulator is set at 4.5-5 lbs.

 

[Anonymous]

What type of upgrades have you done to your ignition? After installing the MSD6, hot coil and good wires my carb problems went away.
Ken

 

[Falcon Ranch]

That sounds like great news for me...I have yet to install my AL6 ignition box...I have a stock dizzy with Pertronix points replacement...because of the higher compression and short trips to work, I don't think my plugs or engine are getting to proper running temp...my plug wires are also in excellent condition with only about 500 miles on 'em as well as the cap and rotor and the coil is the hotter blaster one.

I was planning on cleaning the plugs, adjusting the carb some more by turning the mixture screws in just a tad and maybe compensate the lower idle by kicking up the curb idle...hopefully this will lean it out a bit so it wont keep fouling the plugs and also get that ignition box installed...I am hoping this will help keep the plugs cleaner or do you think I should go to a hotter plug ...does anyone know the recommended plug gap for the Pertronix

Thanks for the help guys...I hope it will be a day and night difference...before this load problem when it was running good, my truck could smoke the tires with no problem and chirp 2nd gear always :thanks: