Here is the problem. this is a 12 degree 598" BBC I have an APD Gas carb on it(brand new) when I start the car up and whack throttle idle stays higher and slowly comes back to the normal idle. I know this isnt proper. thing will be 300 rpm higher and then finally settle back at proper idle.I need to get this remedied before I hit the track. Any ideas of what to look for? I am not a carb man so not sure what to start looking at. I do know the blades are returning to the set position as I have checked that already. Thanks
I have a message in to APD. I think the fuel bowls look high as they are almost at the top of the site glasses, but not sure where they want them set. fuel pressure at 7 psi and Ill have to dig out build sheet and see what bleeds are in it.
lower the floats a half turn by turning the nut clockwise. Lower the fuel pressure to 6.5 with the engine running. If you have a liquid filled gauge replace it first with a dry gauge.
Posts: 13522 | Location: NJ | Registered: August 20, 2000
Go to 5.5 to 6 psi on fuel pressure. Measure the floats with the bowls upside down, .825-.850 in the rear, .850-.875 in the front. As far as idle, make sure you have no vacuum leaks and linkage is not sticking.
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Posts: 1050 | Location: Florida | Registered: November 16, 2007
you likely have a vacume leak,spraying with carb cleaner or something else will show.it also could be the idle circuit is just too rich causing an odd butterfly setting.(providing linkage is not sticking)
honesty is the best policy,insanity is a better deffense 1.036, 6.16@ 224
Posts: 1467 | Location: texas | Registered: February 17, 2006
Originally posted by jmarkaudio: Go to 5.5 to 6 psi on fuel pressure. Measure the floats with the bowls upside down, .825-.850 in the rear, .850-.875 in the front. As far as idle, make sure you have no vacuum leaks and linkage is not sticking.
Hopefully you'll have better luck than I did with them calling back. I got tired of waiting and sent it to Mark Whitener and he resolved the issues. Sure wish they knew what Mark does.
Posts: 3 | Location: 91740 | Registered: April 15, 2020
Best to keep calling, they really don't like returning messages. My guess would be air bleeds either plugged or need a different size. I assume you have tried changing idle mixture screws? If they don't really change the way it acts it probably needs different bleeds.
Posts: 398 | Location: Indiana | Registered: January 20, 2020
The blades are most probably sticking...typically the rear. Everyone of the APD carbs I have do this...5 of them from 1150 to 1250 to 1450. All billet and all inside of 3 months to 2 years old.
Frankly I am sick of it, if it's not that they leak from the accelerator pumps even brand new or redone at APD. ALL OF MINE DO THIS! I was told to "lube" the blades with WD 40 every morning? WTF? If we take the bowls off once it seems like the floats stick on the jet with regularity as well.
No, not from an over a thousand dollar carb...I should not have to lube it to use it. It should not leak anywhere inside of the 1st month's of ownership either nor after return of service.
I just bought a another brand. GET M. Stainless throttle blades. No sticking of the throttle blades, meaning it will idle correctly all the time, no leaks, no lube required, just as consistent with no issues. After 1 weekend I am blown away with the "quality" differences and will buy more carbs and even different brands to see what's better. I also can't make a determination off of one weekend of use either so will continue use and see what sufaces.
I will not settle for a carb I have to "rig" returns for the secondary for it to function correctly (shouldn'tthis come with the carb), nor will I "lube" a carb everyday prior to use. I am tired of "kicking" the throttle in high gear to get the idle back down as well as pulling gas pedal backwards from under the gas pedal with my foot to attempt to get it to idle BACK down.
Looking to try some other brands as well in search of the possibilities of getting a better components. I have had less issues from the gas APD carbs then the alcohol carbs for sure. A lot of carb builders are assembling with APD parts and using different components to avoid these issues. Considering a Ken Jones, May as well as a BLP too. I am willing to try those IF needed to see an improvement...JMO.
I have spoke Randy and my motor builder has spoken with the owner of APD...wasn't like nothing was ever said to them.
JUST my experience...not everyone is having issues I am told.
Originally posted by TORQIN: This one has been eating at me for a while...
The blades are most probably sticking...typically the rear. Everyone of the APD carbs I have do this...5 of them from 1150 to 1250 to 1450. All billet and all inside of 3 months to 2 years old.
Frankly I am sick of it, if it's not that they leak from the accelerator pumps even brand new or redone at APD. ALL OF MINE DO THIS! I was told to "lube" the blades with WD 40 every morning? WTF? If we take the bowls off once it seems like the floats stick on the jet with regularity as well.
No, not from an over a thousand dollar carb...I should not have to lube it to use it. It should not leak anywhere inside of the 1st month's of ownership either nor after return of service.
I just bought a another brand. GET M. Stainless throttle blades. No sticking of the throttle blades, meaning it will idle correctly all the time, no leaks, no lube required, just as consistent with no issues. After 1 weekend I am blown away with the "quality" differences and will buy more carbs and even different brands to see what's better. I also can't make a determination off of one weekend of use either so will continue use and see what sufaces.
I will not settle for a carb I have to "rig" returns for the secondary for it to function correctly (shouldn'tthis come with the carb), nor will I "lube" a carb everyday prior to use. I am tired of "kicking" the throttle in high gear to get the idle back down as well as pulling gas pedal backwards from under the gas pedal with my foot to attempt to get it to idle BACK down.
Looking to try some other brands as well in search of the possibilities of getting a better components. I have had less issues from the gas APD carbs then the alcohol carbs for sure. A lot of carb builders are assembling with APD parts and using different components to avoid these issues. Considering a Ken Jones, May as well as a BLP too. I am willing to try those IF needed to see an improvement...JMO.
I have spoke Randy and my motor builder has spoken with the owner of APD...wasn't like nothing was ever said to them.
JUST my experience...not everyone is having issues I am told.
You really need to give Tony Morris Carburetors a call at 1 407 405-3756 also check out his Facebook page. He worked for BLP as a carb tech then shop forman also worked at Get"M Garage as a carb tech and worked with Mark Whitener as a carb tech. Very sharp carb guy and great service! He just finished doing a 1250 alcohol carb for my 582. Just a super nice guy.
IHRA ACDELCO Canadian Nationals Top/et Iron man Champion Don Davis 57 Corvette Super Gas roadster SDPC Race Shop 582 Head Hunter on alcoholThis message has been edited. Last edited by: 57 Vette,
Posts: 268 | Location: Toronto Ont/Surprise AZ | Registered: August 18, 2003
Originally posted by TORQIN: This one has been eating at me for a while...
The blades are most probably sticking...typically the rear. Everyone of the APD carbs I have do this...5 of them from 1150 to 1250 to 1450. All billet and all inside of 3 months to 2 years old.
Frankly I am sick of it, if it's not that they leak from the accelerator pumps even brand new or redone at APD. ALL OF MINE DO THIS! I was told to "lube" the blades with WD 40 every morning? WTF? If we take the bowls off once it seems like the floats stick on the jet with regularity as well.
No, not from an over a thousand dollar carb...I should not have to lube it to use it. It should not leak anywhere inside of the 1st month's of ownership either nor after return of service.
I just bought a another brand. GET M. Stainless throttle blades. No sticking of the throttle blades, meaning it will idle correctly all the time, no leaks, no lube required, just as consistent with no issues. After 1 weekend I am blown away with the "quality" differences and will buy more carbs and even different brands to see what's better. I also can't make a determination off of one weekend of use either so will continue use and see what sufaces.
I will not settle for a carb I have to "rig" returns for the secondary for it to function correctly (shouldn'tthis come with the carb), nor will I "lube" a carb everyday prior to use. I am tired of "kicking" the throttle in high gear to get the idle back down as well as pulling gas pedal backwards from under the gas pedal with my foot to attempt to get it to idle BACK down.
Looking to try some other brands as well in search of the possibilities of getting a better components. I have had less issues from the gas APD carbs then the alcohol carbs for sure. A lot of carb builders are assembling with APD parts and using different components to avoid these issues. Considering a Ken Jones, May as well as a BLP too. I am willing to try those IF needed to see an improvement...JMO.
I have spoke Randy and my motor builder has spoken with the owner of APD...wasn't like nothing was ever said to them.
JUST my experience...not everyone is having issues I am told.
Chris as close as you are to DaVinci you might give him a call. BLP makes throttle plates with bearings on the shafts also if a guy wants to go that way.
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Posts: 3142 | Location: KIEFER, OK. | Registered: August 17, 2007
A little update after working on carb Saturday, I am now leaning toward the blades binding up in the bore. it just feels catchy when adjusting the idle screws. I really think the blades are catching the walls of the throttle bores, you can her what sounds like scraping when you back the adjustment all the way off and start screwing them in again. Now what to do to fix it? Really sucks spending that kind of $ and its not right. Thanks for all the help guys. appreciate it.
I may try and send it to Bob Book or Mark Whitner to get it fixed. we will see what happens. cant have carb idling high and slowly dropping while trying to stage dragster up.
I sent mine to Book over the winter to get freshen. No significant issues before outside of it occasionally idling higher after a burnout. A couple quick rips of the throttle would fix that before setting the auto-start. Excellent customer service at Book and works great so far.
Posts: 127 | Location: Richmond, VA | Registered: December 07, 2002
Originally posted by Buck2248: A little update after working on carb Saturday, I am now leaning toward the blades binding up in the bore. it just feels catchy when adjusting the idle screws. I really think the blades are catching the walls of the throttle bores, you can her what sounds like scraping when you back the adjustment all the way off and start screwing them in again. Now what to do to fix it? Really sucks spending that kind of $ and its not right. Thanks for all the help guys. appreciate it.
Not surprised. There is a bolt on deal to help this issue, bolts on to the secondary linkage to remove the play from the primary linkage so the throttle return spring helps to close the secondaries,,, band aid fix but it will work until it's fixed right. BTW Royal Purple sells a good throttle shaft lube in spray can form. Works good, Option B!
