Engine Tuning

[Fairlane514]

Yes,they should be turned the same amount.........for highest vacuum.

[gildardo01]

the way i adjust the choke is in the morning try to start your engine it should stay idling a little higher than normal... if its too fast lean the mixture.. if it stalls enrich the mixture... adjust it, once you think its not too fast nor too slow that it stalls... let the engine warm up and the rpms should come back down... always make sure that when the engine is warm the choke is fully open... a choke that doesn´t open all the way will cause bad mpg... 

[hondarider188]

thanks gildardo that helps alot, do you know what type of rpms i should be looking at? and how do i tell if the choke is open all the way? it is a manual choke and i shut it off once it starts(if i needed it). and also the engine wont run with the choke on at all. And for you fairlane i thank you also looking at my A/F screw right now they are not even judging off of the direction the flathead slot it facing.

[gildardo01]

well for a stock engine your rpms once warm should be about 700 but if you have a larger camshaft or an automatic tranny then the rpms are a bit higher... sometimes up to 900-1000... just try to keep it as low as possible to save gas while idling such as red lights and stuff... and a choke fully open is completely vertical.. if you have a manual choke then you can shut it off once the engine warms up to the point where it can sustain idle rpm with out stalling.. on cold morning this may be longer that during the middle of the day... if the engine wont run with the choke on then you may be having too rich of a mixture... for the record both screw will never be equal at the direction of the flathead slot.. you measure the them by turns.. start by closing the two screws.. then turn them two turns out.... for example one screw may be like this / and the other slot will be like this -- but they are equal in how much fuel is being metered.. makes sense.. to tune your carb start with the screw being out 2 turns each... the engine should start..turn the idle screw to adjust your rpms to about 800-900.. turn the mixture screws clockwise until the engine wants to stall turn counterclockwise half a turn and you should be in the ball park for a good tune... all this is with a warm engine... if you have a vacuum gauge use it and go for the least amount of fuel going to the engine and getting the best reading from the gauge.. another tip for a healthy engine and good mpg... a clean air filter...

[hondarider188]

alright i see what your saying now. and i was looking at my rpms after my drive home from work since the engine was warm and i was running about 750 so i think i am a touch high. And just to verify to start out turn hte mixture screws in all the way then out 2 turns as a base measurement. then continue counter clockwise until i hit 800-900 then in until the engine begins to stall then back out 1/2 a turn. and play with it from within that half turn until best vacuum. Then a couple more questions does the A/F mixture screws also adjust the choke? so what i mean by that is when i have the engine tuned in according to the instructions above my choke should also be set right. and yes i did check the valve for the choke and it appears to open all the way when shut off. Then the last question, if i remember right isnt their 2 idles screws? so what is the situation their or do you think i even need to mess with it? i have a vacuum gauge on its way so hopefully i will be able to get it done this week once its here. and thank you so much this helps a ton.

[gildardo01]

yeah you got it figured out, remember the end result should be the lowest rpm possible about 700.. once you get it to 800-900 you adjust the idle screw once more at the end... the function of the choke is independent from the mixture screws.. if the carb is tune properly then the choke wont be a problem... the choke is only there to restrict air flow this causing more fuel to enter and raising rpms to warm up the engine faster and prevent it from stalling.. i went to look at my edelbrock and your right there seems to be two idle screws... i have only used the top one the one that can be turned using a 1/4 nut driver.... once you get the carb in the ball park.. check your timing, then recheck your carb... check your spark plugs make sure their clean, since you were running a little rich they may have darken excessively.. good luck and keep us updated

using that vacuum gauge really helps... you install it and start tweaking the carb until you see what the engine likes... simple and precise.. 

[hondarider188]

alright thanks. im still a llittle confused about adjusting the idle screw. so after i take the mixture screw out 2 turns i adjust the idle screw to 800-900 rpm. and then turn in until begins to stall. and out half turn. and once at highest vacuum turn idle down to about 700.

[gildardo01]

check out this video... https://www.youtube.com/watch?v=HwPFiGENMw8

the tuning details start about at the 4:30 time

hope this kinda helps a little...

[hondarider188]

yeah the video does help a little, but unfortunatly for me i didnt see it until after i got done tuning the carb in. so i ended being turned in about 1/4 more than i originally was. and i was wondering what should i be pulling on a vacuum assuming that i dont have any leaks. the reason i ask is the gauge that i got is saying only about 12 inches and it is responding correctly when i give it some throttle but it didnt really increase when i was adjust the mixture screws, i think that the gauge may be faulty i got it on ebay for about $20, so it might be

[Fairlane514]

If you have a stock cam you should be in the 15-17 inches of vacuum range, or better. Its possible you have a vacuum leak, the cause should tell you that. Are there any ports unplugged on the carburetor? Do you have power brakes?

[Boone83K10]

a manual choke is exactly what it says. You make the adjustment based on how the engine behaves at that moment. An automatic choke can be adjusted for rpm at wide open throttle..with the car off obviously

[Captkaos]

No they won't be adjusted the same.

[hondarider188]

alright today in auto's class i pulled my truck in and tested the vacuum with a reall gauge and i was getting about 15-16 of vacuum. and i have the carb adjusted at the highes which is the 16 inches of vacuum. i ended up being about 1 1/4 turns out. so i will have to see what kind of milage i am getting on my next tank and see how much that quarter turn did for me. I think i might end up getting a new carb anyway, not sure when but sometime. so what recomendations do you guys have for a carb that gets good mileage and has plenty of power. i was think like a quadrajet or a holly? and what size do you think i would need. (1983 k10 5.7L)

[Captkaos]

How much mileage are you expecting out of it.  TOPs would be 17mpg on the highway, otherwise your looking at 12mpg average.

[Fairlane514]

What is your initial timing?  Quadrajet gets pretty good mileage because of the small primaries.