I have a 1970 chevelle with a new 350 bored 30 over w/an RV cam. I installed a edlebrock intake manifold with a edlebrock 600 cfm carb. I have checked the timing, vaccuum, fuel psi, adjusted the carb floats and dwell. at an idle i am about 900 rpms and idles great. the problem is when driving and step on the gas it begins to pop and backfire. it also loses power going up a hill. can anyone offer suggestions about my problem. I have heard that a calibration kit may be needed to correct it but thats not a sure thing.

Which Edelbrock manifold do you have?

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Tino #28 Gold
72 Malibu 350-300,700R4
83 Grand Prix LJ 305

I have the Edlebrock performer series
intake

I had a 8.5 compression 350 with the same stuff you have (RV cam, 600 edelbrock w/perfomer intake, summit hei). It would idle at 500 rpm. I have a much larger XE284 cam now, and i still idle at like 700. Why is your idle so high? My guess is the timing isn't right on, and that also affects how it will idle. What is your timing at? Which kind of vacuum do you have the dist plugged into?

chris

or it might be a vacuum leak. I've had intakes i installed leak fom the underside before. Now I know to retorque several times after driving it a couple hundred miles. Those middle 2 bolts on each side seem to like to come loose...... good luck

[This message has been edited by bulb122 (edited 07-23-2002).]

You'll need the Edelbrock adapter plate for using a square bore carb on a dual pattern intake such as the Performer. Jegs carries it for $5.99. Your local speed shop should have it. Not using it can create a vaccum leak.

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Tino #28 Gold
72 Malibu 350-300,700R4
83 Grand Prix LJ 305

Tino right on! If you already have this adapter plate, are you running points or HEI? If points, have you checked the dwell? If the dwell is changed, you need to reset the timing. Don't forget (I know this is basic, but you never know) to disconnect and plug the vacuum line when adjusting timing.
Fred

Hey guys, thanks for the help. got home last night and decided to take a look at my intake manifold and check the torque. end up pulling the entire intake assembly and replacing the gaskets. I had two small air leaks on both sides of the carb and it was messing everything up. I will finish tonight with reinstalling the dist. and retiming and rechecking the intake manifold bolts. again, thanks for all the help. http://www.chevelles.com/forum/biggrin.gif

Glad you found something. I hate looking for something broken or wrong and coming up empty handed! Was the intake gasket leaking around the middle on each side? Were the bolts loose at all? Just wonderning. (so I can pay even closer attention to these areas in the future! http://www.chevelles.com/forum/wink.gif)

chris

bulb122 - the intake gasket was leaking on
both side of the manifold where the EGR tunnel is. directly underneath the carb.
you won't notice anything when you first start it up. I even put a little soapy water there to if it would bubble, nothing
happened. but when I took it for a spin and
brought the temp up, parked and opened the
hood and looked very close, I could see the leak. the bolts were torqued but once the manifolded heated up it created the problem.

[This message has been edited by stewart (edited 07-26-2002).]

In the future when checking for a vac leak, some WD-40 or an unlit propane torch around suspected areas of leak works mint. Spray or follow gasket areas with 40 or torch and just listen to your idle speed. If it gos up you found the leak in that area. Works better than trying to blow bubbles. http://www.chevelles.com/forum/biggrin.gif

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