idle mixture

[mtdrydock]

hey guys, I don't have a vacuum gauge or anything and am having some troubles setting my idle mixture on a Lean Burn Thermoquad. First I hooked up a tach and dialed in and set where the idle RPM was highest. This usually works pretty good for me. Not so this time. I have done it a few times and i experience surging under light throttle. The plugs were dark brownish with 2 plaugs nearly black. I fiddled around more and found the richer i take it the more it surges and the leaner the less it surges but it is harder to start. I have since turned both screws to the stops and backed out 2 turns. then started up and turned each screw in until the idle dropped off and backed out 1/2 turn. I just don't want to be too lean.

 

[69hemibeep]

hey guys, I don't have a vacuum gauge or anything and am having some troubles setting my idle mixture on a Lean Burn Thermoquad. First I hooked up a tach and dialed in and set where the idle RPM was highest. This usually works pretty good for me. Not so this time. I have done it a few times and i experience surging under light throttle. The plugs were dark brownish with 2 plaugs nearly black. I fiddled around more and found the richer i take it the more it surges and the leaner the less it surges but it is harder to start. I have since turned both screws to the stops and backed out 2 turns. then started up and turned each screw in until the idle dropped off and backed out 1/2 turn. I just don't want to be too lean.

I go high idle and then lean it out a little its just the idle circuit your not going to affect rich it is while driving. :cents:

 

[mtdrydock]

It drives great everywhere else now, just under very light throttle, just above idle.


hmmm... i'm feeling a performer intake/carb combo coming on.

 

[SomeCarGuy]

I'm gonna say you have a leak. Time for carb cleaner test.

 

[mtdrydock]

I ended up fixing 5 vacuum leaks, then completely removed about 13.2miles of vacuum hose, vacuum amplifer, etc and have a pretty strong running car. Today I picked up a CH4B of Ebay. Trying to sell a Holley #4779 double pumper to get a more street friendly edelbrock. I know a lot of you hate them, but I know my way around them and feel more comfortable with one.

Thanks for all the help guys!

 

[SomeCarGuy]

Just don't get the 1407 Eddy. Those 750's are just plain ole junk.

 

[mtdrydock]

Just don't get the 1407 Eddy. Those 750's are just plain ole junk.

Around here we know them as good street carbs, while the holleys are more for the strip. My friend get 3mpg better with a performer than his 4150 on the same car.

What is your opinion on the 1806?

 

[SomeCarGuy]

The rest of the Eddy line is pretty good. The 1405 is the number I recall for the smaller 600 carb.

The AVS carbs are suppose to the better, but I ahven't used the Eddy versions. The OEM ones are pretty sweet IMO for street.

I just know from my experience and others that the 750 carbs are junk. I tinker until a carb runs like EFI, but those just don't respond. Supposedly Eddy is aware of a problem in the design and decided not to spend the $$$$$$ to correct it.

I didn't catch what engine you are running but Amazon used to sell the 650 AVS for about 316.00

 

[69hemibeep]

The rest of the Eddy line is pretty good. The 1405 is the number I recall for the smaller 600 carb.

The AVS carbs are suppose to the better, but I ahven't used the Eddy versions. The OEM ones are pretty sweet IMO for street.

I just know from my experience and others that the 750 carbs are junk. I tinker until a carb runs like EFI, but those just don't respond. Supposedly Eddy is aware of a problem in the design and decided not to spend the $$$$$$ to correct it.

I didn't catch what engine you are running but Amazon used to sell the 650 AVS for about 316.00

I have the Carter Comp 750 and its sweet, I just don't know what Eddy did to them