New carb.... blue smoke????

[72k5mike]

I have just swapped my POS holley 600 for a rebuilt motorcraft 2100 2bbl that was from a 351w.

The new carb runs great and pulls better at low rpm then the 4bbl would, but I have noticed that when the truck idles for a bit and then I give it throttle, i get a puff of blue smoke.

I have yet to put the pcv hose to a vacuum, so that might be the problem, but I just wanted to pick some minds.....

could it be too rich at idle?

 

[K85 Octane]

blue smoke = burning oil

are you sure it's blue or black?
and yes, hook up the pcv line

 

[nvrenuf]

could it be too rich at idle?

blue smoke = oil burning

black smoke = gas / rich


Sorry but if it's blue smoke the carb is not to blame, she's most likely showing age.

 

[NorCal_Chris]

Usually off idle smoke like that is valve stem seals.

 

[84 k5 blazer]

Hook your pcv up........without it you build a lot of pressure in the motor which will push oil out the dipstick and anywhere else it can.

 

[diesel4me]

Hook your pcv up........without it you build a lot of pressure in the motor which will push oil out the dipstick and anywhere else it can.

DING-DING--Winner Winner,Chicken Dinner!....

Hook that PCV valve up,THEN see if it still smokes..I bet thats all it is ,if it never puffed before....I'm curious to see what you'll get for gas mileage with that 2 BBl,I had one of those carbs on a' 72 350 using a carb adapter to bolt it to the GM 2 bbl intake and it ran great,got between 13 and 17 mpg...

I never could get rid of an off idle "bog" with the original 2GC Rochester carb it had and I had that Motorcraft 2 bbl I bought at a swap meet for 5 bucks,still "new" in the rebuilt box it came in,plus I had a bucket full of all kinds of carb adapters--why not!...worst part of the swap was getting my detent cable adjusted right,I had to invent some linkage peices ..

 

[NorCal_Chris]

i have no pcv hooked up, and no smoke :P

 

[diesel4me]

Then your lucky,your engine must be tigt" and have zero blowby--most engines will have some blowby and without a PCV valve,it will build pressure in the crankcase and force it past and thing like rings,out the seals,dipstick tube,etc...
Old cars had no PCV valve,instead they used a breather cap on the oil filler tube,and had a "road draft tube" attached to the crankcase,that pulled the blow by out with the airflow passing by the end of the road draft tube,it creates suction..

I wouldn't run an engine without a PCV valve for long,it encouages sludge formation,and the other things mentioned above..carbs are designed to be used with one,they are calibrated to make up for the vacuum "leak" a PVC valve creates,removing the PCV valve and blocking the vacuum port off will richen the fuel air mixture quite a bit...a lot of folks think its just another "stupid anti-pollution" devise they can dissconnect,but its not,though it does reduce eissions,its a critical thing to have,it keeps the oil cleaner and the engine running more efficiently...

 

[72k5mike]

thanks for all of your help guys. it seems to have gone away with the pcv hose connected. might have just been condensation and the lighting. all seems good though


Thanks!!!