engine smoke! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

renagadebee34 · 01-02-2009, 04:49 PM

i finally got my engine to run and it starts up great but will not run off choke!! and it smoke really bad! some poeple have told me it might be that i have to change the jets in the carb! its a edelbrock 750 double pumper! any help? i just wanna drive it down the road once haha

James McClure · 01-02-2009, 06:25 PM

Renegade, what color is the smoke? Black is to much fuel, blue is oil and white is water. If you need to keep her choked it would suggest the carb is lean OR, you have a huge vacuum leak. Look everything over again. Did you replace the intake?Are all the vac lines attached? Specifically the brake booster or is the booster bad? Is the timing right? How is the float level? Eliminate potential problems 1 at a time befor you go and try to rejet the carb. Keep us posted, jim

72 CustomCamper · 01-02-2009, 06:26 PM

What color is the smoke? Black would be too rich on the carb. White would be water/coolent. Blueish would be oil...

Chuck

piecesparts · 01-02-2009, 08:06 PM

What model of Edelbrock and if it is a "Squarebody" carb, is it mounted on an intake with a spreadbore design? This could be your problem.

A 750 Edelbrock is a lot of carb for a standard 350 Small Block, if that is what you are working on.

renagadebee34 · 01-05-2009, 09:44 AM

thanks guys, yeah everyone has told me that it is to much carb for my 350 and it is blackish smoke and it makes ur eyes water in about 2 seconds! i have checked. ill go through and check all of my vacuum lined today after work

Hoods69BadBowTie · 01-05-2009, 04:55 PM

Damn ya that would be too rich if its just black smoke. Defiantly a big carb for a 350 SB. Probably going to have to mess around and get it adjusted in just right to get it to run good. I would eliminate all your vacuum lines too.

renagadebee34 · 01-05-2009, 05:13 PM

how do i elimate my vacuum lines? how do i adjust my carb? i know i sound stupid but im really not that bad haha

66truckin · 01-05-2009, 05:27 PM

Quote:

Originally Posted by renagadebee34

how do i elimate my vacuum lines? how do i adjust my carb? i know i sound stupid but im really not that bad haha

do you really have to run this carb? You are just way overcarb'd. Get a 600 cfm carb or better yet a stock quadrajet.

piecesparts · 01-05-2009, 06:31 PM

I agree on "to BIG of a carb for a street driven truck. The air flow in that intake will be poor with that big unit, uhless you can keep the RPMs up above 2500. The smaller carb (600 or 650) will give a better air signal and air mix of the fuel. The higher velocity of the air will also give the truck a better low end torque indication and also keep the additives from plating out on the intake valves. Once you have a smaller carb installed, you may want to change jets or needles, as necessary, to get the performance set.

Adjusting the carb can be done different ways. The idle screw is set to maintain the engine in an idle condition (In Drive) at about 650 to 750 RPM---however, you can set it just a little higher if you want.

The vacuum is BEST set with the use of a vacuum gauge, but you can do it by ear and listen for idle changes as you move the screws in and out. Most carbs are usually set around 2 to 2 1/4 turns out on each screw. I use the vacuum gage method, myself. This is done by connecting a plain vacuum gauge to the intake manifold---Now with the idle set at about 700 RPM turn either one of the air mixture screws inward to the seat and watch the vacuum signal on the gauge. As you turn that screw out, you will notice the vacuum reading increase. Once you reach a point that turning the screw any further the reading does not change, then turn the screw back to the point where the increase stopped. Do the other screw the exact same way. Once you have adjusted the screws to get a setting NOW do them one more time to fine tune the setting of the screws. The final thing is to turn each of the air mix screws inward an 1/8th of a turn--you are done.

**Corts60** · 01-05-2009, 06:49 PM

What most people don't realize is Q-jets came from the factory with 750 and 800 cfm ratings. The only reason square bore 750's and spread bore 750's run different on the primary circuit is because of the size of the bore (larger bore, larger jets). Yes a square bore 750 is too much carb for stock 350 but a spread bore 750 is factory. Q-jets have huge secondaries and that is where it makes up the rest of the cfm.

So in closing an edlebrock 600 is a lot smaller than your factory Q-jet, although it is pretty much maintenence free and not temperamental like the venerable Q-jet...

Just my .02.

Albatrossian · 01-05-2009, 09:43 PM

I'm running a 780cfm QJet with a stage 1 kit and that thing is like a lightswitch. Nice and crisp, doesn't run lean or rich and doesn't bog. I ought to take it off and have it bronzed for prosperity..

PhilaTruck · 01-05-2009, 09:56 PM

You're right on Albatrossian: Q-jets aren't that bad, just misunderstood. Understand the circuits, get it running and it will hit.

renagadebee34 · 01-06-2009, 09:09 AM

man thanks for all your help guys? can i find any used ones or reconditioned that are cheaper than sale price?

01-02-2009, 04:49 PM	#1
renagadebee34 Registered User Join Date: Mar 2008 Location: Big Sandy, Texas Posts: 81	engine smoke! i finally got my engine to run and it starts up great but will not run off choke!! and it smoke really bad! some poeple have told me it might be that i have to change the jets in the carb! its a edelbrock 750 double pumper! any help? i just wanna drive it down the road once haha __________________ girls love guys like me!!!!!!

01-02-2009, 06:25 PM	#2
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	Re: engine smoke! Renegade, what color is the smoke? Black is to much fuel, blue is oil and white is water. If you need to keep her choked it would suggest the carb is lean OR, you have a huge vacuum leak. Look everything over again. Did you replace the intake?Are all the vac lines attached? Specifically the brake booster or is the booster bad? Is the timing right? How is the float level? Eliminate potential problems 1 at a time befor you go and try to rejet the carb. Keep us posted, jim __________________ 1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shotJim or Paladin whichever you choose.

01-02-2009, 06:26 PM	#3
72 CustomCamper huh ??? Join Date: Nov 2002 Location: Fredericksburg,Va. Posts: 3,368	Re: engine smoke! What color is the smoke? Black would be too rich on the carb. White would be water/coolent. Blueish would be oil... Chuck __________________ 90 Blazer Silverado 350w/ 700R4 and 32" Kelly's "I am a bomb technician. If you see me running try to keep up!"

01-02-2009, 08:06 PM	#4
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: engine smoke! What model of Edelbrock and if it is a "Squarebody" carb, is it mounted on an intake with a spreadbore design? This could be your problem. A 750 Edelbrock is a lot of carb for a standard 350 Small Block, if that is what you are working on.

01-05-2009, 09:44 AM	#5
renagadebee34 Registered User Join Date: Mar 2008 Location: Big Sandy, Texas Posts: 81	Re: engine smoke! thanks guys, yeah everyone has told me that it is to much carb for my 350 and it is blackish smoke and it makes ur eyes water in about 2 seconds! i have checked. ill go through and check all of my vacuum lined today after work __________________ girls love guys like me!!!!!!

01-05-2009, 04:55 PM	#6
Hoods69BadBowTie Chevys Kick A$$ Join Date: Jan 2005 Location: Zootown, MT Posts: 12,699	Re: engine smoke! Damn ya that would be too rich if its just black smoke. Defiantly a big carb for a 350 SB. Probably going to have to mess around and get it adjusted in just right to get it to run good. I would eliminate all your vacuum lines too. __________________ HOODS is what I answer too -'79, '77, '88 Pickup Sold, '85 Camaro, '83 T/A, '81,'83,'90 K5 Blazer All Sold -'79 3/4 ton "Big Yellow Bananna" Lifted 4spd. 39.5 TSL Swampers, The money Pit -'86 K5 Blazer Silverado 6.2 4" lift 35"s -'95 Ext. Cab Shorty 4" Tuff Country rolling 35" M/T's -'83 Monte Carlo T-Tops. 126,500 Original Miles -LATER I would rather push a Chevy then drive a ford!!

01-05-2009, 05:13 PM	#7
renagadebee34 Registered User Join Date: Mar 2008 Location: Big Sandy, Texas Posts: 81	Re: engine smoke! how do i elimate my vacuum lines? how do i adjust my carb? i know i sound stupid but im really not that bad haha __________________ girls love guys like me!!!!!!

01-05-2009, 06:31 PM	#9
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: engine smoke! I agree on "to BIG of a carb for a street driven truck. The air flow in that intake will be poor with that big unit, uhless you can keep the RPMs up above 2500. The smaller carb (600 or 650) will give a better air signal and air mix of the fuel. The higher velocity of the air will also give the truck a better low end torque indication and also keep the additives from plating out on the intake valves. Once you have a smaller carb installed, you may want to change jets or needles, as necessary, to get the performance set. Adjusting the carb can be done different ways. The idle screw is set to maintain the engine in an idle condition (In Drive) at about 650 to 750 RPM---however, you can set it just a little higher if you want. The vacuum is BEST set with the use of a vacuum gauge, but you can do it by ear and listen for idle changes as you move the screws in and out. Most carbs are usually set around 2 to 2 1/4 turns out on each screw. I use the vacuum gage method, myself. This is done by connecting a plain vacuum gauge to the intake manifold---Now with the idle set at about 700 RPM turn either one of the air mixture screws inward to the seat and watch the vacuum signal on the gauge. As you turn that screw out, you will notice the vacuum reading increase. Once you reach a point that turning the screw any further the reading does not change, then turn the screw back to the point where the increase stopped. Do the other screw the exact same way. Once you have adjusted the screws to get a setting NOW do them one more time to fine tune the setting of the screws. The final thing is to turn each of the air mix screws inward an 1/8th of a turn--you are done.

01-05-2009, 06:49 PM	#10
Corts60 Just here to tinker Join Date: Jun 2008 Location: Holland, MI Posts: 3,697	Re: engine smoke! What most people don't realize is Q-jets came from the factory with 750 and 800 cfm ratings. The only reason square bore 750's and spread bore 750's run different on the primary circuit is because of the size of the bore (larger bore, larger jets). Yes a square bore 750 is too much carb for stock 350 but a spread bore 750 is factory. Q-jets have huge secondaries and that is where it makes up the rest of the cfm. So in closing an edlebrock 600 is a lot smaller than your factory Q-jet, although it is pretty much maintenence free and not temperamental like the venerable Q-jet... Just my .02. __________________ 78 C10 SWB Diesel #1 (wrecked)http://67-72chevytrucks.com/vboard/s...1978+silverado 78 C10 SWB Diesel #2 (sold)http://67-72chevytrucks.com/vboard/s...d.php?t=650751 60 GMC Suburban (sold)http://67-72chevytrucks.com/vboard/s...d.php?t=445526 60 GMC 1000 (sold)http://67-72chevytrucks.com/vboard/showthread.php?t=298235 67 GMC 1500 (sold) http://67-72chevytrucks.com/vboard/s...d.php?t=803695 73 Chevy C20(Daily)http://67-72chevytrucks.com/vboard/s...d.php?t=852767 86 Suburban(summer unit) http://67-72chevytrucks.com/vboard/s...d.php?t=810697 88 Suburban 4x4(sold)

01-05-2009, 09:43 PM	#11
Albatrossian Georgia Boy Join Date: Jun 2008 Location: Douglas, Georgia Posts: 370	Re: engine smoke! I'm running a 780cfm QJet with a stage 1 kit and that thing is like a lightswitch. Nice and crisp, doesn't run lean or rich and doesn't bog. I ought to take it off and have it bronzed for prosperity.. __________________ 81 GMC High Sierra, 2WD, 357ci/700R4, 3.73s, posi.

01-05-2009, 09:56 PM	#12
PhilaTruck Right on the line, baby! Join Date: Oct 2003 Location: Phila, PA 19130 Posts: 1,486	Re: engine smoke! You're right on Albatrossian: Q-jets aren't that bad, just misunderstood. Understand the circuits, get it running and it will hit. __________________ 83 GMC 406 th400/3.73 Eaton Truetrac posi, headers, x pipe, & racePros. Tubular control arms, lowering rear springs, caltracs. Still ugly, but getting built right, although slowly Click and scroll down for site vendors! Subscribe here!

01-06-2009, 09:09 AM	#13
renagadebee34 Registered User Join Date: Mar 2008 Location: Big Sandy, Texas Posts: 81	Re: engine smoke! man thanks for all your help guys? can i find any used ones or reconditioned that are cheaper than sale price? __________________ girls love guys like me!!!!!!



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.