Just put a cam in my 98 C5, Have a few ?s
12-24-2002, 10:52 PM
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Just put a cam in my 98 C5, Have a few ?s It will be a few months before I can send the computer off to be programmed. Has anyone ever drilled a hole in the TB blade to help it idle? I know that people enlarge the existing hole on an f-body, but what size hole should I drill if it would help. When I do get around to having the computer done, will the hole be messing it up? The cam I used is a comp 224/228 568/571 112lsa. I also have FLP headers without cats, flowmaster cat back, and a k&n fipk sys. Can anyone tell me an estimate of how much power my car should make after tuning?
12-24-2002, 11:04 PM
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Re: Just put a cam in my 98 C5, Have a few ?s I would take a drill bit and drill the next size up from the current hole size and try it. If it still idles rough or die. Go to the next size.. Give the pcm time to learn between checks. I would ride around atleast a day between changing the hole size. If you go to big you will have real idle problems..
12-25-2002, 08:28 PM
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Re: Just put a cam in my 98 C5, Have a few ?s I have had my cam in mine for 6 months and do not have any tuning, just a drilled throttle body. I have heard upwards of close to 20hp gain with prgramming.
12-25-2002, 10:44 PM
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Re: Just put a cam in my 98 C5, Have a few ?s I drilled a hole for my TB, refer to the drill bit sizes I posted in this link:
https://ls1tech.com/ubb/cgi-bin/ulti...c;f=1;t=005824
https://ls1tech.com/ubb/cgi-bin/ulti...c;f=1;t=005824
12-25-2002, 11:01 PM
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Re: Just put a cam in my 98 C5, Have a few ?s Since the C5 doesn't have a hole from the factory I wasn't sure what size to even start with. I knew that everyone says to go one drill size bigger at a time, so I was thinking of starting around a .075 hole and then working my way up from there. Will drilling the hole have any negative effects such as idle being too high after I send the computer to Ed Wright? Also where at on the TB blade should I put the hole?
<small>[ December 25, 2002, 11:02 PM: Message edited by: Nick Williams ]</small>
<small>[ December 25, 2002, 11:02 PM: Message edited by: Nick Williams ]</small>
12-26-2002, 12:59 AM
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Re: Just put a cam in my 98 C5, Have a few ?s If you port/polish your throttle body it'll be like adding a hole to the blade due to the way the C5 TB works. If you have a dremmel and a few free hours, I'd recommend porting/polishing the throttlebody first before drilling a hole.
I have pics of the porting on my site in the infopics section.
I have pics of the porting on my site in the infopics section.
12-26-2002, 05:52 AM
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Re: Just put a cam in my 98 C5, Have a few ?s I used epoxy downstream of my air bypass valve to block air flow. I then drilled a .161 diameter hole in the epoxy to allow some air flow. I can now use my throttle stop screw to adjust my idle and don't need to drill a hole in my throttle plate. This also eliminates the slow to idle problem when decelerating.
