Throttle body hole size help
Throttle body hole size help This is my first heads/cam LS1. I wondered what would be a good starting point for throttle body hole. I'll include cam specs. This is in a A4
Comp XER grind
228/228
581/581
2 degress advanced
112 lobe seperation
Comp XER grind
228/228
581/581
2 degress advanced
112 lobe seperation
Joined: Nov 2001
Posts: 34,629
Likes: 2,549
From: Schiller Park, ILL Member: #317
Re: Throttle body hole size help With a cam of that size I am guessing you will need to raise your idle (via turning TB set screw or tuning) and drill the hole to probably at least 13/64ths. I would get the idle to a point (rpm) you like it at, then start with an 11/64 hole. Gradually move up if needed till IACs are in the 30-35 range. 11/64...3/16...13/64...7/32...15/64. I would not go larger than 15/64 on the stock hole. I would start a new small hole instead if needed.
My TB hole is at 13/64 with a 800rpm idle for my 221/221//.558//.558//114 cam. My IACs are in the 45-50 range...I am planing to enlarge the hole further or start a new smaller hole in the spring to get my idle a little more stable.
My TB hole is at 13/64 with a 800rpm idle for my 221/221//.558//.558//114 cam. My IACs are in the 45-50 range...I am planing to enlarge the hole further or start a new smaller hole in the spring to get my idle a little more stable.
TECH Enthusiast
Joined: Nov 2001
Posts: 712
Likes: 1
From: Dallas,Texas
Re: Throttle body hole size help I have the hotcam and M6. I had idle problems
with the AC on. I have the hole drilled to 15/64"
It was better but the real fix was to add a
.022" ( 26ga tin i think) shim on top of the idle
set screw.. go to big and you will throw a
high idle code.. this is the old Trooper Mod.
I have no idle problems at all now..
with the AC on. I have the hole drilled to 15/64"
It was better but the real fix was to add a
.022" ( 26ga tin i think) shim on top of the idle
set screw.. go to big and you will throw a
high idle code.. this is the old Trooper Mod.
I have no idle problems at all now..
