Wierd Sound from carb

[JFlanny11]

Hey Guys,

Long story Short, I start a new Job tomorrow and I'm hearing a very strange noise out of my carb. The best I can describe it is two dim sounding Ticks then a very loud Snap. I hear it through all my gears and the more I accelerate the quicker it gets. The engine (360) is running extremely rough too. I just installed an edelbrock performer intake and carb about 2 months ago and its been running fine. Any Guesses or where to start?

Thanks

[jeepsr4ever]

I would do a timing check. Also did your carb come with some instructions like turning the two mixture screws in clockwise all the way until it stumbles then turn them out 1/2 a turn?

[JFlanny11]

Ill check the timing, and yes I have adjusted the mixture screws.

I just went back outside after it warmed up and raced the engine up a little. The snapping sound went form once every say 2 sec to about 5 times a second. This is the first time ive expirenced that since all this happened

[jeepsr4ever]

Doesnt sound right! I would suspect a burned intake valve or bad timing. Did you do anything else but do the intake and carb swap?

[JFlanny11]

No thats all I replaced....... a few months before that I replaced the dist with an HEI. New plugs and wires when I did that!

Could it be cracked ceramic on a Plug or a misfiring plug?

[jeepsr4ever]

I woudl check the timing and routing of your wires. 1-8-4-3-6-5-7-2

[JFlanny11]

Ok Ill do that, Thanks man

[woodfar51]

maybe you should check for bent push rod or bad rocker.

[JFlanny11]

So I checked the wires plugs and distributer. They are all fine, the timing is fine too. When I seat the passenger side mixture screw on the carb. The loud Tick stops completely....Then when I get on the gas again it comes back, and stops once its at idle.

Does this help?

[Goose]

sometimes all of us overlook the obvious.. are you sure that the noise is coming from the carb?? and not bouncing off the hood?? could it be an exhaust leak? or a metallic tapping sound?? they sell cheap stethoscopes (like 6 bucks) to help you track the sounds down..

here is how I would trouble shoot this.. first hook a vacum gauge to the intake if the needle is pulsing back and forth, suspect a burned valve or collapsed lifter..if it did it all the time I would say maybe a bent push rod, clicking can also be caused by a rocker bridge cracked in half. pop the valve covers and check by hand all the rockers.

If the needle doesnt pulse, and the engine isn't missfiring all the time it could be a plug wire arcing or arcing in the dist cap..

the most important thing is to locat the sound then think about all the things things that can cause the sound you find..

If it is coming out of the carb throat, it has to be valvetrain or timing related.. the intake valve is open at the wrong time or it is firing at the wrong time with a valve open.. if it is a ticking or snapping type sound it could be as mentioned above exhaust leak, or something mechancial hitting or a bad plug wire arcing to ground somewhere. my guess is that when you close that mixture screw it is changing the rpm of the engine and that changes the either the frequency of the sound or makes a little more noise to mask it.

But my bet is with it running rough.. you have a pushrod/rocker/ burned valve issue, if you are sure you have checked the wires and cap for arcing.

I hope something in this helps.. good luck.