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I have a Holley 750 DP with Proform main body that is suddenly driving me nuts. The other night it popped a little and caught fire at the street races. I noticed when I started it up it didn't like to idle but ran good enough to get it home.

I started it up the next day and it idled only around 400 rpm's and popped back thru the carb a few times. I pulled the bowls and cleaned them up, replaced the power valve even though this one checked out ok. I replaced needles and seats and gaskets, reset float levels and fired her up. She still will not hardly idle at all.

I turned the main idle screw and after a full turn and a half it idles up and suddenly revs up to 2500 rpms, I turn the idle screw slowly back off and nothing, then suddenly the idle tanks to 400 rpm's and fights to idle. Any idea's? I played with the 4 corner screws some and it still runs like shit.

I have had this carb for 8 yrs and it always worked very well until now. I built it and have rebuilt it twice since the original build . Maybe it is time for a new one.

Any thoughts or idea's would be appreciated!

Signed stumped in Dallas...LOL
 

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check and see if it has a power valve in the front metering block, pull off front bowl ...if it backfired good chance it is bad....replace it or put in block off plug and jet it
 

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Discussion Starter #3
check and see if it has a power valve in the front metering block, pull off front bowl ...if it backfired good chance it is bad....replace it or put in block off plug and jet it
It has anti blow out but I did check it and it was good. I replaced it anyway as I went with a 2.5 instead of a 3.5. Damn thing makes a lousy 5.5" of vacuum in gear.
 

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Discussion Starter #6
First thing that comes to mind possibly distributor issue. Might give that a shot.
It's a MSD pro-billet with mech. advance. When you say distributor problems are thinking timing, loss of? I did try and advance it and it's good and tight, no movement. That said I can put a timing light to it tomorrow and see if it is still set at 32 degree's total.
 

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It has anti blow out but I did check it and it was good. I replaced it anyway as I went with a 2.5 instead of a 3.5. Damn thing makes a lousy 5.5" of vacuum in gear.
The power valve should not affect idle fuel mixture. you have no fuel coming out of your boosters at idle. My car idles at 4.5" and has a 6.5 power valve in it.
 

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Ok, it's official! I am a dumb ass...LOL I found the problem. I have a 3 step MSD retard box and have a one stage/step set up to pull 5 degree's of timing at the flip of a switch. My Grandson had been playing in the car and flipped the switch. therefor I have found out my car doesn't like to sit and idle with 5 degree pulled from the timing......note to self, never assume a 3 yr old will not screw with stuff in your car, even when you are watching him!!!

Thanks for all the helpful hints/tips, I appreciate it!

Flame away.....
 

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Ok, it's official! I am a dumb ass...LOL I found the problem. I have a 3 step MSD retard box and have a one stage/step set up to pull 5 degree's of timing at the flip of a switch. My Grandson had been playing in the car and flipped the switch. therefor I have found out my car doesn't like to sit and idle with 5 degree pulled from the timing......note to self, never assume a 3 yr old will not screw with stuff in your car, even when you are watching him!!!

Thanks for all the helpful hints/tips, I appreciate it!

Flame away.....
No need to flame, just glad you figured it out. Sometimes the simple stuff is the biggest pain. Good luck
 

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Yeah. Thats a cheap fix haha. Thats always good. Wont nobody fame ya for that. We all do stupid things. Well i do
 

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ha ha kids will get ya. My wife said her suburban started to make a noise and felt a vibration. She called me twice about it so I took a ride with her as soon as I got home. She makes the first turn and says she you feel that. I said babe its in 4wd. SHe laughs and says opps my 2 yearold was playing driver when she cleaned the car and he turned the 4wd on
 

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Ya I hear I have my tranny out and I hate to even let my 3 year old daughter in the shop cause she likes to play with everything ha ha. Gotta love her drive to help though.
 
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