some black smoke at idle with holley 2 barrel

fatstax · COBOURG, ONT

some black smoke at idle with holley 2 barrel

flatblack55delivery · PORT HOPE, ONT

Maybe you should quit using husk juice. Ed

fatstax · COBOURG, ONT

nah, the rat truck gets the good stuff. on the holley site the problem i am having is described as the power velve being blown but i installed a brand new one, weird

Dubya31 · SPRUCEDALE, ONT

What power valve is in the carb, and how much vacuum are you running at idle?

fatstax · COBOURG, ONT

funny you say that, the power valve opens at low vaccum, i wonder if i have a bad vac leak or im simply drawng low vaccum. funny it runs great through the rpm range and seems to idle ok.

sasquatch · NORTH BAY, ONT

Rob, just checked my book,, Points 16-18 which i'm sure you have, Max vacumn advance-10-12 crank degrees, timing-6 beforeTDC, plug type shows an AC-48!! (with a .025 plug gap.) Coil amp draw with the engine running should be 2.5.

Plugs too cold, and gap too wide possibly?

fatstax · COBOURG, ONT

i customized an hei style chev distributor to the engine so no points as such. im thinking big vaccum leak, might be why the idle screws have no effect on the idle. but thanks that info is handy

fatstax · COBOURG, ONT

im not using the vac advance either, i wonder if that might be a problem?

sasquatch · NORTH BAY, ONT

Did the idle screws change the engine before???

(An AC 48 plug is plenty HOT!!)

fatstax · COBOURG, ONT

not that i can recall since i had ignition problems so it hasent really ran right. i wonder if a intake vac leak would still allow it to run but the air being drawn in would make the idle screws not do anything, im putting a vac gauge on it tommorow to check it out

fatstax · COBOURG, ONT

i think the plugs are 43 or 42, did ac plugs get hotter with lower numbers back then?

v8deuce · OAKVILLE, ONT

Ya I'm leaning towards a vacum leak also,I was going to say to use a propane torch and follow along the intake to head and around carb a higher rpm would suggest a leak but if it already has black out the back adding more fuel won't help or it might?? just thinking out loud =)

Randy

fatstax · COBOURG, ONT

as i understand the holley power valve, low vac makes it open, so if im not drawing alot of vac at the carb it could be loading the motor with fuel at the wrong time, makes the most sense to me so far

Lightspeed Mike · BELLEVILLE, ONT

Carb er a tore, Carbonmaker, Carbondater, Car bean shaker ?
Haw heck just put some Fuel injection on it and call it fixed!! biggrin biggrin

Bruce Rossiter · TORONTO, ONT

If your carb is a 2300 series, the following info might help.

According to Holley, the size of the power valve is determined by dividing the idle vacuum by 2. So if your vacuum at idle is 18, divide that by 2 and install a 9 power valve. One small engine backfire can destroy a power valve and there's a kit you can install in the throttle plate to prevent this.

Black smoke at idle generally indicates a rich mixture and the place I would check would be the float level adjustment (just to the bottom of the inspection hole).

Also there is a check valve below the accelerator pump squirter that may be missing or too light in weight. The squirter also has a small gasket above and below it to seal the fuel from leaking from around the attaching screw.

This is just a few guesses that might help.

Molten · CAMBOURNE, ONT

Rob
I have a 2.5 power valve you can try. Also have a 4.5. If this is your issue, the 2.5 will solve it.
Let me know.
Shawn

-- Edited by Molten on Friday 11th of October 2013 08:11:00 AM

slim · DUNDAS, ONT

This might help if your getting an odd reading . bottom of page

http://www.secondchancegarage.com/public/186.cfm

fatstax · COBOURG, ONT

i think i know what the problem is, i have low vac as i had a vac gauge in the dash hooked up and i was only drawing around 5 inches, i had assumed the gauge was faulty but this also would explain why my vacuum brake booster is not working very well. that tutorial was pretty handy and does explain a great many things. funny though why would it run so well given a large leak like that?

sasquatch · NORTH BAY, ONT

Geez, only 5 in of vacumn?

And AC plugs always got hotter in range as the number rose. 42 and 43's are pretty cold.

fatstax · COBOURG, ONT

originally i thought the vac gauge i have was faulty buy now i think its not, how complex can a vacuum gauge be?

Seeker1056 · DOURO, ONT

its a vacuum issue for sure, and absolutely your power valve is open at idle as all stock Holleys come with a 6.5 power valve - so if you only have 5 inches at idle - bingo - its open

just for ****s n giggles idle the motor up to 900 rpm or so and I bet the vacuum goes up and the black smoke goes away

if you need help ask - I forgot more about holleys and modifyin them than most people ever learn

fatstax · COBOURG, ONT

yes revving the engine up clears the black smoke and the engine cleans up, i firmly now believe its a leak, which is why my power brakes dont work well. as i stated before im surprised how well it runs even with a leak, how is it possible? your totally correct seeker if you say the holley comes with a 6.5 power valve as you would expect an average engine to draw 15 hg in vac or better

fatstax · COBOURG, ONT

ok so i bought a vac gauge and it was drawing about 14 inches of vacuum, so the vac gauge i had was bad. i replaced the base gasket on the carb and set the idle screws, now its drawing around 17 to 18 inches of vac. i also hooked up the vac advance. it still seemed to be smoking a bit at idle and a puff when i revved it, i also checked the power valve and it has stamped on it 4.5. this is what came with the kit i bought. so i drove it around tonite and it seemd to run better, when i got back i pulled a plug thinking maybe the plugs were bad but now instead of the sooty black they are the right colour, a dark tan brown. perhaps the plugs cleaned up but im sure i still see the black at idle and for sure when i rev it. maybe carb has defect letting gas in.

sasquatch · NORTH BAY, ONT

At least you got decent vacumn now. Your'e gettin close!!

oldkoot · BROCKVILLE, ONT

It's normal to get a little black puff when you jab the gas, accelerator pump shot. Try lowering the float level, might solve the "black" idle.

fatstax · COBOURG, ONT

its not too bad now except still some smoke at idle but i am noticing fuel coming out of throttle shaft when i shut it off

-- Edited by fatstax on Sunday 13th of October 2013 08:01:23 PM

Bruce Rossiter · TORONTO, ONT

Sorry to hear you're still having problems with your Holley carburetor.

Bruce Rossiter · TORONTO, ONT

fatstax wrote:
its not too bad now except still some smoke at idle but i am noticing fuel coming out of throttle shaft when i shut it off

-- Edited by fatstax on Sunday 13th of October 2013 08:01:23 PM

The 2 spots that I can think of that would drop fuel on the throttle shaft are the accelerator pump squirter (as I mentioned above) and the boosters. The transfer slot is under the throttle plates and shouldn't leak fuel on the shaft. If the squirter isn't leaking, check the gasket on the metering block to main housing to make sure you have the right gasket in place. Sometimes a metering block gasket from a 4 barrel secondary will get mixed up in a kit. I bought a kit of 10 gaskets and 1 gasket was wrong and that's the one I used by mistake.

You could also have a worn housing in the throttle body that could be sucking air through the throttlwhen its running and seaping fuel when you shut the engine off.

fatstax · COBOURG, ONT

the throttle shaft has a lot of play in it, i am looking for a new base plate, i wonder if that could be a problem making the carb leak fuel?

Bruce Rossiter · TORONTO, ONT

fatstax wrote:
the throttle shaft has a lot of play in it, i am looking for a new base plate, i wonder if that could be a problem making the carb leak fuel?

You can repair the throttle body by installing bushings. It's a pretty simple fix to ream the throttle body and press in the bushings. I have a reamer but I'm almost positive I don't have any bushings left.

fatstax · COBOURG, ONT

i know i can bush the shaft but i dont have a way easier than buying a new base to machine out the one i have, they have to be pretty dead on to work. i might play around with it later but i want a quicker fix

Bruce Rossiter · TORONTO, ONT

fatstax wrote:
i know i can bush the shaft but i dont have a way easier than buying a new base to machine out the one i have, they have to be pretty dead on to work. i might play around with it later but i want a quicker fix

You're right, buying a new throttle body is the best way to go. The reamer I have is self aligning and designed specifically for reaming Holley throttle bodies. Best of luck with your carb leak.

Gwillyville Kid · BRADFORD, ONT

Holley Carb, I love 'em but they do need good fuel filters. Chances are you have a bit of dirt OR a small piece of metal (a piece of broken off threads) on the needle valve. Remove float bowl, remove float, remove needle & seat assy, blow out clean off needle tip, blow off seat and reassemble. To adlust float turn float bowl upside down and adjust to belt line of brass float or plastic float to about about level. Final fuel adjustment to where gas just trickles out hole on side of tank (brass screw) when engine is idling.

These are the same as a running toilet. It won;t stop leaking (flooding ) until you fix it. The mixture screws won't make any difference and the vacuum will be low until you fix it.
Adjust spring on accelerator pump linkage to "just" a 0 to 1 thousandths clearance when choke is completely open. NOT BINDING!

Use a 5 micron fuel filter. you might have to change to a spin on type to get a 5 micron filter. I believe Summit sells 5 micron in line filters.
A mid 90's Chev/GM fuel injection filter, with proper 3/8 line adapters is an excellent choice OR a Ford Tempo fuel filter, with metal nipples out each end is also an EXCELLENT choice. I know the Tempo filters are a little large, but, the are a fine, 15 or less micron filter. Factory Carburator filters are 20 to 40 microns. There is so much garbage in the gas we buy we need to filter better.C
By the way, engine timing. Do you think Warren Johnson uses factory timing for his Pro Stock to factory timing specs?
Due to potential looseness in your engine's timing chain or from a delayed camshaft advance timing until engine kicks back against starter while cranking. That is TOO much initial timing. Back off a few degrees until engine will spin over and start. Check that setting and record. That is likely your new initial setting. Then check mechanical advance. It should max by 36 with 93/94 octane. If you have "recurved" your Distributor you may have to use a slightly heavier spring to slow rate of advance. This will be evident if accelerate under load (driving) and hear a rattle from timing. You could back off the initial but that will slow acceleration. You want all the advance curve it will handle without detonation. After you achieve a good mechanical and initial check Vacuum advance. It should NOT pull past 45. Ideally 38-40, without detonation. Vacuum advance is for some measure of fuel economy.
You can follow this set up program with regular fuel and get an increase in performance and fuel economy. Premium will net better results UNLESS you are doing all the above and do not get detonation. In that case use regular gasoline.
MID Grade gas is normally "Chef's Surprise" because gas stations are NOT supposed to dump regular gas in the super tank but sometimes do. Normally when they do not have any more room in Regular tank and have to empty tanker before it leaves station. Guess where the rest of that regular goes?

Check out Hot Rod Magazine's "Hot Rod to the Rescue". There is excellent ACCURATE information in this feature. It is in each month Hot Rod. Might save you some grief or $$$$$$$$.

the Kid

fatstax · COBOURG, ONT

i have pretty much checked most of the stuff you described and found a few things that could cause this, i have narrowed it down to the throttle shaft being quite worn and this might be causing me grief so i have ordered a new base plate for it. the season is pretty much over anyways so its going away for the winter soon.

hemi43 · ONTARIO

Maybe the used muffler you put on was full of oil ???

fatstax · COBOURG, ONT

why didnt i think of that? and to think this forum survived without you