Im having a carbon build up prob.

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SRT_DSTRHOLC

SRT_DSTRHOLC

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The new bigs carb is in and its amazing, but my friend is Having run on probs again and Carbon build up. We took the plug out and we can wipe the black powder off the spark plug. I think he said the timming is at 34 and im going to lower it to 18 initial with 32 total

this is what The plug looks like its a NGK FR 4
The carb is a Bigs 750 Stage 5

the idle scres are adjusted to 1 turn in the front and 1/2 turn in the back....

it haas 74s in the front 82 in the rear
4.5 PV in the front and no PV in the rear

.033 primary shooter .033 secondary shooter


idle feeds are .032 and the idle bleeds are .070 and mains are .033

what needs to be done?

IMG_058722222.jpg
 
Your kiddin me right Burnt!?!?!

throw the carb away.... LOL


Seriously, get a jet kit and jet it down in size.
 
I have a jet kit, This is just how the carb was set up from Jesse at bigs
 
and Im only 85ft above sea level I believe and were I race its 35
so would this effect the air bleeds?
 
YES! Oh yes. If you have adjustable air bleeds, they can be changed out and set up for a better running carb. This we know and is good for dialing in every last tenth.

Now where to go with this is another story and your up for a trial and error deal.

Do remember, a carb dialed in perfectly is only good for half the day. Then the days conditions change and the carb is out of tune once again.
 
I just want the carb not to have carbon build up. It doesnt have to be perfect. Just were I can drive it with out worrying about anything...

The plug gap is also at .040 with full msd ignition
 
Good ignition and gap spec. It may be possible to go wider. Nethier here or there.
Just try a new set of plugs and jet down a bit. Go in steps of 2.
 
I want to leave the jets were they are so i think im going to go up in the idle bleeds and no the vac is 8-9 in gear but i will recheck it
 
so i think im going to go up in the idle bleeds
Click to expand...
The idle bleeds? You mean air bleeds?

These are for fine tuning and the A?F ratio curve. This is not your issue.
 
going up in air bleeds wouldent help clear the plugs?

We did this with the other crappy holley i had.. and I had 68in front and 72 in rear and still nothing...
 
Some things to remember....

The idle circuit is for idle.

Being rich at idle is not the same as being rich under load.

Playing with the idle circuit will do little if anything to your cruse/load air fuel ratio.

Drop the jets 2 numbers and see what it does.

When it cleans up start adjusting by 1 number to dial it in.
 
so i messed with them and now i have a good plug..Little hard to get a reading since they are carbon fouled but..I tweaked the idle screws and went around the block and took the plug out and no carbon of it.. The threads are clear and just the porclean is little blackish because of before
Edit/Delete Message
 
1968FormulaS340 said:
Um.... A trip around the block on old plugs won't tell you anything.
Click to expand...

IT wont tell me anything? Theres no more carbon on the plugs.. so It must have helped.. I just wanted the carbon gone..Its to hot to take it out for a drive. I will take it out when it cools down and go for a Drive
also there not old plugs. I just put them in when i got the carb
 
ya, thanks guys.. Just did he said just to mess with the idle mixture screws and if that dident help. He would send me some Air bleeds
 
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