Small popping/backfire after new Edelbrock carb install.

[RCSConstruction]

I put an edelbrock marine carb in and am getting a small steady backfire out the exhaust. More pronounced at mid throttle. I adjusted the timing to 6btdc and 30* at 3000 rpm's, getting good spark and adjusted mixture screws for best vacuum. (16psi)
Is this a lean or rich condition?
Anybody have a similar motor (vortec 5.7, boat info in my signature below)) and have dialed in their carb? Wondering if it may need new metering rods?
Was a 2bbl motor that ran fine. My manual shows the same spark plugs for both carbs.
Any idea's?
Thank you

 

[mkpj1]

Re: Small popping/backfire after new Edelbrock carb install.

I always thought an exhaust pop was either an exhaust leak or electrical. double check all your electrical while running if you haven't already. I would double check that you don't have a vacuum leak somewhere either although I think that would pop out the carb. Same with a lean condition.

I did have to re-jet an edel on a car once for being too lean. I would contact Edelbrock or go to their website if someone here can't help you.

Good Luck.

Ken

 

[hoof harted]

Re: Small popping/backfire after new Edelbrock carb install.

maybe ya got the timin wrong. i remember the time i marked the timin marks on my boat wrong on the howdoyado an set the timin off the wrong marks. damn thing sounded like a shotgun goin off. then i did the points. someone finally tol me ya got it backasswards. damn coors. then there was the time i dumped prestone in the gas tank so she wouldn't freeze up over the winter. had ta suck out the gas with a garden hose after that deal. ya shoulda been there the time i put the prop on but forget ta tighten down the nut. got out on the lake an she wouldn't move. lost the dang prop an all. i ain't got that boat no more. sold her for a case a coors. but that's a whole different story an i had bad luck with her anyway.

 

[sea wolf]

Re: Small popping/backfire after new Edelbrock carb install.

Please tell me that you've given up boating for good.

 

[WaterWitch2]

Re: Small popping/backfire after new Edelbrock carb install.

maybe ya got the timin wrong. i remember the time i marked the timin marks on my boat wrong on the howdoyado an set the timin off the wrong marks. damn thing sounded like a shotgun goin off. then i did the points. someone finally tol me ya got it backasswards. damn coors. then there was the time i dumped prestone in the gas tank so she wouldn't freeze up over the winter. had ta suck out the gas with a garden hose after that deal. ya shoulda been there the time i put the prop on but forget ta tighten down the nut. got out on the lake an she wouldn't move. lost the dang prop an all. i ain't got that boat no more. sold her for a case a coors. but that's a whole different story an i had bad luck with her anyway.

Maybe you should switch to Bud?

 

[hoof harted]

Re: Small popping/backfire after new Edelbrock carb install.

don't know sea wolf. but i got a line on a used bayliner. gonna need help.

 

[mkpj1]

Re: Small popping/backfire after new Edelbrock carb install.

LMAO!! You guys made my day!

 

[RCSConstruction]

Re: Small popping/backfire after new Edelbrock carb install.

LOL......
Anyway...

The old carb had a vacuum port for the PCV valve and the edelbrock didn't.. So I used the vacuum port off the manifold (installed an elbow) I put my finger over the PCV valve and the popping went away...... So I plugged back up the manifold port and she is purring like a kitten...
Got lucky I guess, never would have thought it would have been it but I was leaning to an air leak..
Is it because the vacuum port on the manifold only draws suction from one runner? (unbalanced vacuum?)
I stuck a regular breather cap where the pcv valve was. Bad? OK? should I find a spacer for the carb that has a vacuum port and re-install the pcv?
Thanks!

 

[mkpj1]

Re: Small popping/backfire after new Edelbrock carb install.

Ohhh, ya that would do it. PVC is emissions and runs blow by gasses to get reburned at the carb. My PVC (85 3.0L) is hollow and it runs to my Flame Arrestor. I would imagine that is a boat marine application you would want to have these unburned hydrocarbons sent back into the system and not vent into your bilge? find a flame arrestor with a PVC connection would be my opinion.

Ken

 

[FreeBeeTony]

Re: Small popping/backfire after new Edelbrock carb install.

If I'm reading this right, you put a fitting on the intake manifold and connected it to the breather on the valve cover...........I would venture to guess that this is your problem. Put the plug back in the manifold and find a flame arrestor with the proper fitting for the breather tube.

 

[RCSConstruction]

Re: Small popping/backfire after new Edelbrock carb install.

I have 3 hoses going to my flame arrestor. The PCV will only work with manifold vacuum. I hollowed out my pcv valve as well and stuck the hose end into the flame arrestor. I didn't like having just a breather cap. I think I will try and find a spacer that sits under the carb with a vacuum port.
Thanks again all.