Crossfire idles too high? Why?
Thread Starter
Racer
Joined: Oct 2011
Posts: 417
Likes: 2
From: Blacksburg Virginia
Crossfire idles too high? Why?
I bored the tb to 2". Did all the other crossfire hacks for more air and fuel pressure.
now when I try to balance tb, I cannot get idle lower than 975 in gear.
the rear tb is sitting on the stop (set screw not engaged) and the plate is still not 90deg to the bore. I can get the front plate to close 90 deg.
so I don't know if there is a vacuum leak or if something is screwed up. I tried the old propane trick, but haven't found a leak yet.
advice appreciated.
now when I try to balance tb, I cannot get idle lower than 975 in gear.
the rear tb is sitting on the stop (set screw not engaged) and the plate is still not 90deg to the bore. I can get the front plate to close 90 deg.
so I don't know if there is a vacuum leak or if something is screwed up. I tried the old propane trick, but haven't found a leak yet.
advice appreciated.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
I thought that we talked about this already?
http://forums.corvetteforum.com/1583888445-post10.html
If you can't find a vacuum leak, remove the TB's, shine a light through the bore from one end, looking into the other end. The light getting past the throttle blades will reveal where your new blades are failing to seal to your new bore. HAND trim the blades and/or bore w/sand paper until the blade seats evenly all the way around the bore.
I assume that you're having this high idle issue with the IAC passages blocked off, right?
http://forums.corvetteforum.com/1583888445-post10.html
If you can't find a vacuum leak, remove the TB's, shine a light through the bore from one end, looking into the other end. The light getting past the throttle blades will reveal where your new blades are failing to seal to your new bore. HAND trim the blades and/or bore w/sand paper until the blade seats evenly all the way around the bore.
I assume that you're having this high idle issue with the IAC passages blocked off, right?
Last edited by Tom400CFI; May 28, 2013 at 10:40 AM.
Thread Starter
Racer
Joined: Oct 2011
Posts: 417
Likes: 2
From: Blacksburg Virginia
we absolutly talked about it in the other thread, but to no avail. I took both TBs off this weekend, and i used a jewlers file to hit all the high spots around the diameter of the plate. The front TB plate will sit at 90° when the linkage to the rear is disengaged....no bind and just a small uniform amount of daylight around it.
the rear TB plate will not sit at 90° because the stop hits the casting where the rear adjustment screw is....ie, even with the screw backed completly out, the plates cannot sit flat. At first I thought it was just a bind in the plate to bore, but it is not.
Anyway, I am trying to determine if the high idle is caused by this rear TB plate not sitting 100% flush, or if there might be a vacuum leak somewhere I can't find.
I appreciate your help in the other thread...and that has led me to where I am right now.
I guess if anyone can tell me if there throttle plate sits 90° to the bore when the rear throttle set screw is completely backed out, that would be the first place to start.
the rear TB plate will not sit at 90° because the stop hits the casting where the rear adjustment screw is....ie, even with the screw backed completly out, the plates cannot sit flat. At first I thought it was just a bind in the plate to bore, but it is not.
Anyway, I am trying to determine if the high idle is caused by this rear TB plate not sitting 100% flush, or if there might be a vacuum leak somewhere I can't find.
I appreciate your help in the other thread...and that has led me to where I am right now.
I guess if anyone can tell me if there throttle plate sits 90° to the bore when the rear throttle set screw is completely backed out, that would be the first place to start.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Mine didn't (sit 90* to the bore) and I've never seen any that did.
If you have one that does, it sounds to me like you filed too much off of it.
Can you put up some pictures of the things?
If you have one that does, it sounds to me like you filed too much off of it.
Can you put up some pictures of the things?
Burning Brakes
Joined: Feb 2013
Posts: 1,173
Likes: 152
From: norway
read this http://www.holley.com/data/Products/...99R9978rev.pdf not for tbi but this is good reading !!!!!!
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Thread Starter
Racer
Joined: Oct 2011
Posts: 417
Likes: 2
From: Blacksburg Virginia
I was using.....
Holley 26-100 - Carburetor Throttle Plate Kit; 2 in. Plate Dia
The bore is a hair under 2in. These plates did bind before closing 100% and then people recommended I sand them. When I hit the spots that were binding I could get them to close 90°.
Now I realize I have to keep them about 5° open. I will take my calipers home tonight and check the diameter of the bore to the diameter of the plates.....I really appreciate your help.
If someone has a different part number to suggest, that would be appreciated.
Holley 26-100 - Carburetor Throttle Plate Kit; 2 in. Plate Dia
The bore is a hair under 2in. These plates did bind before closing 100% and then people recommended I sand them. When I hit the spots that were binding I could get them to close 90°.
Now I realize I have to keep them about 5° open. I will take my calipers home tonight and check the diameter of the bore to the diameter of the plates.....I really appreciate your help.
If someone has a different part number to suggest, that would be appreciated.
Pro
Joined: Jul 2002
Posts: 703
Likes: 0
From: Milwaukee Wi
Mine were bored by a party that has done 100's. I believe Holley Dominator may in fact be larger than 2.00. That is what I was told to buy by machinist. I took apart TB B4 I shipped to machinist. So he did not address the plates. My recollection was that they fit perfectly with no binding. I dont recall sanding to fit but may have. that was 2003.
It may be they are oval 2.00 inch in width by 2.002 in lenght?
It may be they are oval 2.00 inch in width by 2.002 in lenght?
Last edited by Rohn; May 29, 2013 at 03:06 PM.
Burning Brakes
Joined: Feb 2013
Posts: 1,173
Likes: 152
From: norway
orginal plates are 46.97 mm long and 45.91 mm wide = 1.023 % !!!!!! i bored mine to 50,28 mm and used 2" plates ( 50.80 mm ) = 1.023% off ! then you will get the right angle !!! i have bored mine my selves !! on the car , and runs great !! wacuum ports are working !!! the plates are not round !!! meseure the old one and you will know !!!!!
Burning Brakes
Joined: Feb 2013
Posts: 1,173
Likes: 152
From: norway
