Let me start off by saying any help with this month long dilemma is much appreciated.

Man my driver side exhaust sounds like its making popcorn after I installed an edelbrock performer aluminum intake.... Im running a Summit 750 mechanical secondary/choke carb on a 69 455 out of a toronado.... Motor ran fine with the stock intake (out of a 70 455 not a toro low rise intake) but I decided to change to something lighter and ended up with this sound like rocks in a tin can in driver side exhaust but only under load at idle she sounds great.

When I fired it up with the new intake I checked for exhaust leaks by spraying around intake and carb with carb cleaner and no change or fluctuation in idle so Im assuming everything is sealed? I used the mr gasket # 404 on the intake manifold. Initial timing set at 10 degree, I tried running a little richer with no luck. Using 91 octane

Side note, the motor got up to about 220- 230 degree during the 1st start up with new intake and I quickly shut it down. the temperature fell pretty quick on the thermostat after I shut it off. I guess I was in a hurry to jump in a do some donuts and I made the mistake of not topping off the coolant. I topped it off and it ran cool 180 after that.

Thanks for any help with this, I hope its not something too major and if I cant get the setup to work Ill just throw the stock intake back on and hopefully be on the road again!

 

Did you make sure your firing order is correct and all the wires are seated on the plugs and in the cap?

 

Did you put any plugs in the intake heat crossover?
Or was there plugs in the heads when you took the iron intake off?

Gene

 

Do you have the old style exhaust
manifold on the driver side with the
heat riser weighted flap. If so, it could
be worn.

 

Thanks for the response guys,
I checked plugs and wires and were good there.
One thing I noticed is the Mr gasket 404 in take gaskets block the heat crossover? Nut sure what's the point of that and if they would make the sound out the exhaust I'm hearing?
I'm going to check the exhaust manifolds tonight.
Thanks again guys

 

Any chance you got a push rod misaligned, off the lifter or rocker arm? perhaps a valve is not opening now?

 

Another thing is the sound is not noticeable at all in the engine bay, only in the driver side exhaust. I noticed more carbon deposit on the floor where that exhaust dumps down. I'm using Smithy blue streak glass packs. But the sound isnot the regular old glasspack sound.
Its a noticeable rocks in a cofee can sound when I release the gas pedal.... I can't really hear it when I'm on the gas. Maybe i can't hear it because it's too loud in the garage. I may have to drive it but don't want to run the risk of damaging the engine if the current state is not good..Thanks

 

Thanks Steve, would I hear that in the valve cover? Have any suggestions on how to check that?

 

I don't know if this might help but I had the same problem on my olds 1965 dynamic with a 425. I installed the same items and the car ran like crap. I finally had to install the original manifold gasket (metal) with the aluminum manifold and carb and the car ran great! Has been running perfect for 3 years now. For some reason the manifold would not seal correctly with the aftermarket gaskets. I tried 3 sets before I went back to the steel one. I even use a vacuum gauge to check for leaks and before I install the steel one it was showing low vacuum; back to the steel one and the vacuum was reading right on target and the wheels was spinning on takeoff; Herm

 

Thanks Herm, did your exhaust sound like detonation was occurring? Popcorn cooking in the exhaust... I'm wondering uhh it has anything to do with the intake gasket blocking of the heat cross over.... I know the steal stock gasket has the heat crossover open.Thanks again

 

I did find that the intake gasket blocked the heat crossover ...would that cause the sound? Thanks Gene

 

That may be the problem and it did sound like detonation was occurring; somehow it just would not idle and just pop and backfire thru the carb. I even went back to the place that I had bought the setup and they suggested that I try it with the steel gasket original. Sometimes the ole heads know the best

 

Is it running rich and dumping fuel through the carb?

 

The gasket material will burn through in a short while, so the ports being blocked shouldn't cause any issues.

 

It may have been a little rich or filled when first start up but I tuned it with a vacum gauge and its just abiut right. The exhaust may have spit out some extra gas that was dumped in while trying to get fuel back into the carb after the fuel line was unplugged. Im going to try backing down the timing to see if its gets rid of the sound...

 

Man I got a smile ear to ear! Thanks to all your suggestions I went down the list and found the stupid exhaust flap is taking a bit longer to function with this intake and our recent cold weather. After bout 10 minutes if driving the sound went away with the coil in the exhaust manifold heating up. Glad it wasn't nothing bad!
Thanks to everyone for the suggestions. I really appreciate it.
It's great to have real people with experience help me in a crutch:-)

 

Glad you got it figured out!

 

Now that's what we want to hear! This is what these cars are all about. Good job!

 

Glad it's figured out.