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carb tuning #1033857
07/17/11 12:17 AM
07/17/11 12:17 AM
Joined: Apr 2005
Posts: 399
metro detroit
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turner Offline OP
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metro detroit
I need some help getting my carb tuned in, my car seems to not want to idle for anything or seems to be extremely cold blooded. I was at a car show at my work and looked a fool trying to get my car off the trailor and keep it running after. I would get the car started and running and put it in gear and the thing stalls, going into reverse or drive, same thing car just pukes and there I go pumping and cranking the thing to life again. There was two other race cars at the show, both run all motor class at milan on Friday nights and run low 8 second passes they got pushed off the trailor and fire up and instantly are idling at 900 rpm, what gives! I need someone to post a link to the initial idling procedures for a Holley 850, I have four corner idling screws in the fuel blocks and a proform main body. The weather was warm in the middle of the day, even at the track I have a hard time getting the car to start and run at idle initially, after its heated up the car will start rough or act very finicky to over pumping of the throttle. Im just looking for some baseline tuning for my idle, the car runs low 11 second passes in the quarter, so im not upset with the carb totally, it just seems so hard to start, makes my eyes water its so rich as well, my initial timing is about 18 degrees and I dont believe I have any vacuum leaks, thanks for the advice in advance

Re: carb tuning [Re: turner] #1033858
07/17/11 12:33 AM
07/17/11 12:33 AM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
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Romeo MI
Try bumping the timing up more... sounds like its fat...
so you mostly need to open the blades some and turn in
the mixture screws.... how many turns out are they
EDIT
also check the float level

Last edited by MR_P_BODY; 07/17/11 12:36 AM.
Re: carb tuning [Re: turner] #1033859
07/17/11 12:40 AM
07/17/11 12:40 AM
Joined: Mar 2007
Posts: 3,300
Northern Indiana
Dunnuck Racing Offline
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Northern Indiana
The first thing I would suggest is make sure your floats are set correctly,if in doubt lower them until you get it sorted out.
The Proform main bodies usually come with two sets of idle air bleeds for the rear,in case you don't have the rear idle mixture screws.I would suggest checking those next to see if the rear idle air bleeds(the ones closest to the outside of the carburetor) match the ones in the front,if they are a smaller number,they will richen the idle mixture.
After that,I would move on to the timing,see if adding afew degrees will help.Not enough initial timing will make a car hard to get the idle right.
I doubt the timing is your main problem now though due to you stating it smells rich all the time at idle.
One other thing is that the rear idle circuit may or may not work due to the throttle body being set up for it or not,not all of them had the idle mixture transfer slots to use that circuit,that is why the main body comes with two different sets of bleeds. Hope this at least gets you started.
Keith

Re: carb tuning [Re: MR_P_BODY] #1033860
07/17/11 12:44 AM
07/17/11 12:44 AM
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Posts: 399
metro detroit
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turner Offline OP
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I believe that my total timing is at 35 degrees so I could turn it up a few degrees and not be too concerned. As far as the idling screws, I cannot tell off hand, seems to me like I had the car idling and turn them in one at at time until the idle fluttered and then backed off a hair. I had the car idling at 1500rpms and it was just too much so I turned it down, but I didnt think it would kill my starting.

6733100-cuda6.JPG (84 downloads)
Re: carb tuning [Re: turner] #1033861
07/17/11 12:48 AM
07/17/11 12:48 AM
Joined: Mar 2007
Posts: 3,300
Northern Indiana
Dunnuck Racing Offline
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Northern Indiana
I had the car idling at 1500rpms and it was just too much so I turned it down, but I didnt think it would kill my starting.




That is why I suggest the float levels first,and in hindsight,fuel pressure next.
Sounds like it floods over.
Keith

Re: carb tuning [Re: turner] #1033862
07/17/11 12:52 AM
07/17/11 12:52 AM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
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Every time you adjust the throttle blades you need
to go back and adjust the mixture screws (you changed
the air ratio)

Re: carb tuning [Re: MR_P_BODY] #1033863
07/17/11 01:18 AM
07/17/11 01:18 AM
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Posts: 399
metro detroit
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turner Offline OP
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I have the fuel pressure set at 7 lbs, it was dripping lots of fuel down the carb when the idle was set so high. Tommorrow I will get it going and try getting on the idle screws after i have it idling at about 1000rpms, I still want to add a little more timing as well I had it set low for the initial break-in of this new motor.

Re: carb tuning [Re: turner] #1033864
07/17/11 01:39 AM
07/17/11 01:39 AM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
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Romeo MI
Add the timing first when you get it running

Re: carb tuning [Re: MR_P_BODY] #1033865
07/20/11 04:36 PM
07/20/11 04:36 PM
Joined: Nov 2004
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John Offline
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I was told by Proform (actually, Quick Fuel who does Proform's tech work) to set the float level at the center of the sight window. After fighting idle and performance problems, I finally set the float level at the bottom of the sight window and most of the problems disappeared.

My idle was still rough (too rich) and I needed to turn the idle mixture screws almost closed to get a semi-decent idle. Quick Fuel suggested that I try larger idle air bleeds to lean the carb(s) so that I could get more idle mixture screw adjustment. I went from factory .073 idle air bleeds to .075 and it made a huge difference in the idle quality and adjustability.

Re: carb tuning [Re: John] #1033866
07/20/11 07:17 PM
07/20/11 07:17 PM
Joined: Apr 2005
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metro detroit
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turner Offline OP
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Thanks for the input, I just got a 50cc pump kit from Jegs today to solve another issue i have, should have bought some see-through sight glases as well. The weather here has been mid-90's with a heat index of over 100, working 12 hours a day in a hot Chrysler factory doesnt make me wanna go out and fiddle with my ride, although im gunna go out and look at it tonight and see what I can see. Mr P body , I dont suppose you would be around Lapeer and have some time to help a fellow racer out would ya?

Re: carb tuning [Re: turner] #1033867
07/20/11 07:22 PM
07/20/11 07:22 PM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
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Romeo MI
Quote:

Thanks for the input, I just got a 50cc pump kit from Jegs today to solve another issue i have, should have bought some see-through sight glases as well. The weather here has been mid-90's with a heat index of over 100, working 12 hours a day in a hot Chrysler factory doesnt make me wanna go out and fiddle with my ride, although im gunna go out and look at it tonight and see what I can see. Mr P body , I dont suppose you would be around Lapeer and have some time to help a fellow racer out would ya?




I live in Romeo.... I'm working on a customers car
and my own... I havent been going anywhere

Re: carb tuning [Re: MR_P_BODY] #1033868
07/21/11 08:56 AM
07/21/11 08:56 AM
Joined: Dec 2005
Posts: 1,495
Shelby mi.
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JAKE68 Offline
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Shelby mi.
Since it seems like you are a little GREEN with this stuff why don't you bring it to my shop and put it on my dyno and set it up and be done!!!!!!!!!!!!!Give me a call 586 726 6900.


JAKES AUTOMOTIVE
Re: carb tuning [Re: turner] #1033869
07/21/11 09:06 AM
07/21/11 09:06 AM
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck Offline
Not enough dumb comments...yet
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Brookeville, Md
Quote:

I have the fuel pressure set at 7 lbs, it was dripping lots of fuel down the carb when the idle was set so high. Tommorrow I will get it going and try getting on the idle screws after i have it idling at about 1000rpms, I still want to add a little more timing as well I had it set low for the initial break-in of this new motor.




as suggested, check the floats, bump it up to 38* I like to turn them all the way in then back out 1.25 turns and adjust from there for best idle/vaccum. Depending on your camshaft you might need a 1000+ idle speed.


[IMG]http://i66.tinypic.com/pui5j.jpg[/IMG]
Coming soon!!!!
Re: carb tuning [Re: JAKE68] #1033870
07/21/11 12:26 PM
07/21/11 12:26 PM
Joined: Nov 2003
Posts: 4,027
Dearborn Hts, MI
Sledge_57 Offline
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Quote:

Since it seems like you are a little GREEN with this stuff why don't you bring it to my shop and put it on my dyno and set it up and be done!!!!!!!!!!!!!Give me a call 586 726 6900.




I may do this myself........


Doug

1967 "Pedal Car" 500" low deck , TF 727, 4.30 Locker
Best to Date: 11.67 @ 114.9 1.64 60ft

"Kids in cars cause accidents. Accidents in cars cause kids..."
Re: carb tuning [Re: Sledge_57] #1033871
07/22/11 07:22 PM
07/22/11 07:22 PM
Joined: Apr 2005
Posts: 399
metro detroit
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turner Offline OP
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Thanks for the input, I contacted Jakes in Shelby and will be taking it to get tuned on his dyno next week.

Re: carb tuning [Re: turner] #1033872
07/23/11 02:10 AM
07/23/11 02:10 AM
Joined: Nov 2003
Posts: 4,027
Dearborn Hts, MI
Sledge_57 Offline
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Dearborn Hts, MI
Quote:

Thanks for the input, I contacted Jakes in Shelby and will be taking it to get tuned on his dyno next week.




Let me know how it goes, I'm interested in doing this too....


Doug

1967 "Pedal Car" 500" low deck , TF 727, 4.30 Locker
Best to Date: 11.67 @ 114.9 1.64 60ft

"Kids in cars cause accidents. Accidents in cars cause kids..."
Re: carb tuning [Re: Sledge_57] #1033873
07/23/11 12:26 PM
07/23/11 12:26 PM
Joined: Apr 2005
Posts: 399
metro detroit
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turner Offline OP
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I just fixed my problem with the butterflies on my carb not opening all the way, seems the old owner did not have the correct lever on the carb for the secondaries. I changed over to the pump lever supplied in the 50 cc pump conversion kit and now the butterflies are opening completely. I ran multiple 7.19,s in the 1/8th with partial throttle, 34 degrees timing, and shifting at 5400. With the carb problem fixed im taking the car to the dyno to get my timing and jetting set-up, then I will figure when I should be shifting this new combo, Im trying for a 10 second 1/4 mile pass and still street driven, albeit not much.

6743207-carb.JPG (70 downloads)






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