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As spring came overnight here I decided today to awake my Olds from hibernation and have a good ride.
Well, it took me 10mins, then I had 2 misfires (not unusual at my car when it wasnt fired for months). After that I heard a noise from mot dept, so I went back home. Car ran normal. I had this already last year (but just high frequent noise from time to time, but i never found the source). Now it is very loud and in my opinion it is from the carb/igniton area.
What I already did (without success)
— changed the coil
— unplugged and plugged all ports at carb
— removed air cleaner
no change. Just when i higher the rpm, for the few first seconds it seems to be gone.
My thoughts is that it might be something inside the carb, but I have really no idea about the interieur of carbs...
Attached is a video, any help is highly appreciated.
edit: cant upload it, here is a link:
If you put the air cleaner on, does the noise level decrease? Thinking that may help determine if the noise is coming from inside the carb or outside the carb so you know where to start troubleshooting.
ive found vacuum leaks by spraying brake cleaner at the baseplate gasket and vac hoses as well as throttle shaft .engine rpms will increase if there is a leak.Never heard one whistle like that ,perhaps a bad or misaligned baseplate gasket sucking air internally ?
Marc,
Yes, what Fun71 said. Does the noise change with the air cleaner on? If yes its some kind of vacuum leak in or around the carb. Throttle shaft bushings or a gasket?
Sounds like a rotary or rotational sound too. Pull the distributor cap and see if the rotor is making contact with the cap and check the weights under the rotor. Is the points plastic bumper OK? Check for side to side play in the distributor shaft.
Use a long screwdriver or metal rod put between your ear and various spots to listen for the source of the noise. Similar to a doctors stethoscope. Listen to front engine drive accessory noise, alternator, water pump power steering pump, timing chain etc...
The volume remains the same, with or w/o the airfilter.
I didnt check the carb gasket, only thing i looked was for the screws (which have been tightened ok)
Few weeks ago I sold my old carb, narf...otherwise would be easy to swap it to see if its carb related.
Steve, I tale a closer look within the next days to the distibutor, thanks for the support @ all.
sounds like a vacuum leak below the throttle plates to me.spraying carb cleaner in the baseplate area should locate it or i like to use a piece of vacuum hose to listen closely .if you have an adapter plate below the carb that's a good place to start.
I guess you guys hit the nail on the head. When spraying brake cleaner at the carbs base, the motor turned up when I sprayed in the backside area of the carb. Removed it, and the gasket between the spacer and the block was a paper gasket plus in some areas additional rubber gasket. I guess the guy didnt have a new gasket somhe took the old one and added som e rubber. Ah well....
I get asap new gaskets and let you know. Are the paper gaskets the state of the art?
Btw, could someone explain to me why i need an additional adapter plate when I have a Edelbrock carb on a edelbrock manifold??
Well, I am a bit lost now....obviousley I have a 3711 if you see the block plate here.
The spacer which was used was a Mr. Gasket, 1932. Google tells me that this is a "Carburetor Adapter Kit - Square Flange Carburetor to Quadra-Jet 4 Barrel Manifold".
In the Edelbrock 3711 installation guide it says clearly that just stock carbs are supported.
Is that spacer the right part ? (Asking that because I had problems from day 1 with the new engine regarding misfires/noise)
Ok, that's what I get for assuming. If you read the link below it clearly states as Kenneth and I pointed to above, the only carb you can use is a Rochester (spreadbore) carb. The reason is all the others will interfere with the EGR port. So if you want to use an Edelbrock (squarebore) You need the spacer to clear the EGR port. You have the correct spacer to raise and adapt your carb to that manifold.
March 30th, 2019, 08:16 AM
