Slant Six Forum :: Carburetor/Intake recommendations for my rebuilt engine

Ok, bad news - So, I am thinking again that maybe the throttle body has some debris in it. I am thinking of pulling the carb back off and sonic cleaning the throttle body to get any debris/deposits that are in there out.

I am also going to re-time it and try to get it down from the 12 degrees it is at right now.

a quick test drive to go get some gas (91 octane)

If the carb had debris in the passages then I would doubt that it would run smoothly when cold.

I plan on taking the throttle body off and cleaning.

The engine is not pinging. Just thought I would run some good gas in it while tuning

Author:	cmann [ Wed Apr 12, 2023 12:47 pm ]
Post subject:	Re: Carburetor/Intake recommendations for my rebuilt engine
Ok, bad news - After I adjusted the valves and let it run in the garage yesterday I decided to take is for a quick test drive to go get some gas (91 octane). By the time I got down to the gas station it started running rough again and wanted to die. I did try opening the idle mixtures and that did not help any. Again, under power it is smooth with no pause or hesitation. So, I am thinking again that maybe the throttle body has some debris in it. I am thinking of pulling the carb back off and sonic cleaning the throttle body to get any debris/deposits that are in there out. I am also going to re-time it and try to get it down from the 12 degrees it is at right now.

Author:	Jase [ Thu Apr 13, 2023 6:34 am ]
Post subject:	Re: Carburetor/Intake recommendations for my rebuilt engine
Quote: Ok, bad news - So, I am thinking again that maybe the throttle body has some debris in it. I am thinking of pulling the carb back off and sonic cleaning the throttle body to get any debris/deposits that are in there out. I am also going to re-time it and try to get it down from the 12 degrees it is at right now. If the carb had debris in the passages then I would doubt that it would run smoothly when cold. It sounds like this issue is now showing up once the engine has warmed up. Is that correct?

Author:	cmann [ Thu Apr 13, 2023 6:42 am ]
Post subject:	Re: Carburetor/Intake recommendations for my rebuilt engine
Yes, that is correct. Once it is at running temperature is when it wants to start to die when idling. Again, past idle it runs great.

Author:	drgonzo [ Thu Apr 13, 2023 9:33 am ]
Post subject:	Re: Carburetor/Intake recommendations for my rebuilt engine
My son's D100 did the same thing. Debris in the idle circuit.

Author:	Dart270 [ Thu Apr 13, 2023 11:54 am ]
Post subject:	Re: Carburetor/Intake recommendations for my rebuilt engine
Pull idle mix screws and blow out with carb cleaner? Lou

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Author:	SlantSixDan [ Thu Apr 13, 2023 3:03 pm ]
Post subject:	Re: Carburetor/Intake recommendations for my rebuilt engine
Quote: a quick test drive to go get some gas (91 octane) Why are you buying high-test gasoline for this car? From what you've described of the build, it shouldn't be necessary. And if it's not necessary, it's not beneficial—just a waste of dollars. If you have to run 91 or else the engine pings…take out the excessive base timing; get it back around 5° and that should resolve the pinging. Sounds like there is (still) trash in your carb's idle circuit and/or air bleeds.

Author:	SlantSixDan [ Thu Apr 13, 2023 3:05 pm ]
Post subject:	Re: Carburetor/Intake recommendations for my rebuilt engine
Quote: If the carb had debris in the passages then I would doubt that it would run smoothly when cold. If the carb has trash in the idle circuit, you often won't see a symptom until the engine is warm enough for the choke to come off and the fast-idle cam to swing out of the way.

Author:	cmann [ Thu Apr 13, 2023 7:29 pm ]
Post subject:	Re: Carburetor/Intake recommendations for my rebuilt engine
Thank you Dan for your reply/input. Yes, I plan on taking the throttle body off and cleaning. The engine is not pinging. I plan on bringing the timing down. Just thought I would run some good gas in it while tuning. I will keep you posted on the progress/response after cleaning the throttle body.

Author:	SlantSixDan [ Thu Apr 13, 2023 11:57 pm ]
Post subject:	Re: Carburetor/Intake recommendations for my rebuilt engine
Quote: I plan on taking the throttle body off and cleaning. Good, but that might not be where the trash is located. Quote: The engine is not pinging. Just thought I would run some good gas in it while tuning It is a complete mistake to think higher-octane gasoline is better. It is not. Tune the car on the kind of gasoline you'll usually be running in it.

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