Re: carb butterfly question
[Re: turner]
#1030088
07/11/11 01:38 PM
07/11/11 01:38 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
I had a friend over a day ago and while he was over I wanted to verify that I was reaching WOT on the carb with my foot all the way in the kitchen. I got into the car and mashed the throttle and all was good, the throttle could open no further. Just for kicks we took of my air cleaner and tried this as well and realized that my secondary butterfly are not opening all the way up, the butterfly stops about 15 or 20 degrees short of full verticle, leading me and my partner to believe that the secondaries are not opening all the way. I went to the bench and looked at another carb. and sure enough the butterflies on it open all the way and then I can also take them over center, leading me to believe that the carb on my engine is not functioning properly, shouldnt the butterfly on the secondaries stand straight up when WOT is acheived. I took off the fuel bowls and the carb opened all the way up, then reassembled the fuel bowls on to the carb and the butterfly wouldnt open all the way. Is there adjustment on my carb that can cure this problem or do I have bigger problems? The carb is a Holley 850 w/ a proform body and factory base plate. Does anybody have any ideas, after taking it all apart and reassembly all seems the same, im thinking that im only getting about 750 of the 900+ cfms, please help
Look at the linkage rod that goes to the secondary
arm... you can bend the rod to shorten it... it goes
into the slotted secondary arm... the ratio of the
primary and the secondary are different so you open
the primary X distance then the secondary opens on
a faster ratio hence the slot on the secondary
EDIT
If you can move the secondary arm with your hand open
all the way its the linkage rod... if you cant open
it by hand look elsewhere
Last edited by MR_P_BODY; 07/11/11 01:42 PM.
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Re: carb butterfly question
[Re: Cab_Burge]
#1030091
07/11/11 01:58 PM
07/11/11 01:58 PM
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Joined: Jan 2003
Posts: 4,760
Moved to N.E. Tennessee
GomangoCuda
master
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master
Joined: Jan 2003
Posts: 4,760
Moved to N.E. Tennessee
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Wild guess is that during a rebuild the 30cc and 50cc pumps got switched and now the 30cc pump is getting bottomed out by the 50cc cam and lever.
In theory, there is no difference between theory and practice. In practice, there is.
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Re: carb butterfly question
[Re: GomangoCuda]
#1030092
07/11/11 02:03 PM
07/11/11 02:03 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Quote:
I took off the fuel bowls and the carb opened all the way up, then reassembled the fuel bowls on to the carb and the butterfly wouldnt open all the way.
read what I quoted. If taking the bowls off fixes it then it is not a secondary linkage problem. The only thing on the bowls that could restrict the throttle is the Acc. pump.
Yep
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Re: carb butterfly question
[Re: turner]
#1030095
07/11/11 11:30 PM
07/11/11 11:30 PM
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Joined: Aug 2003
Posts: 43,303
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,303
Bend,OR USA
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I hope this picture will help, the left picture of the side arm and accelerator pump cover is the 50 CC, the one on the right is one version of the 30 CC pump cover and arm  There has been several different version of the 30 CC pump cover and, I think, only one 50 CC pump cover  I remove the 50 CC pumps and replace them with the 30 CC pumps on most of the D.P. carbs I work on, especially for Mopar motors  IHTHs.
Last edited by Cab_Burge; 07/11/11 11:38 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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I hadn't thought of that when I was posting my rpely and talking on the phone to another racer about this weekend 
I can't walk and chew gum at the same time anymore 
