Throtle blade holes?
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Le Mans Master
Joined: Feb 1999
Posts: 6,807
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From: Hoosier
Cruise-In III Veteran
Throtle blade holes?
I know that drilling small holes in the throtle blades will help the idle with a lopey cam.
But what would doing the same do with a mild cam? Is it the same result as opening the idle air bleeds in the carb?
Reason I'm asking is that although my carb (Edelbrock 1406, 600 cfm) is tuned in very nicely, it still is rich below about 1200 rpm, and with the overdrive tranny the engine spends a lot of time in that range.
But what would doing the same do with a mild cam? Is it the same result as opening the idle air bleeds in the carb?
Reason I'm asking is that although my carb (Edelbrock 1406, 600 cfm) is tuned in very nicely, it still is rich below about 1200 rpm, and with the overdrive tranny the engine spends a lot of time in that range.
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
With a mild cam and a properly tuned carb there should be no reason to drill holes in the throttle blades.
A big cam sometimes requires you to adjust the idle higher to make it idle correctly and in doing so you open the transfer slots too much and it is not using the idle circuit to idle anymore. In a case like that you drill the holes so the motor can get the air it wants and still keep the idle transfer slots half covered so you will still be using the idle circuit at idle. I just re-read that and while it makes sense...it's time to go to bed
A big cam sometimes requires you to adjust the idle higher to make it idle correctly and in doing so you open the transfer slots too much and it is not using the idle circuit to idle anymore. In a case like that you drill the holes so the motor can get the air it wants and still keep the idle transfer slots half covered so you will still be using the idle circuit at idle. I just re-read that and while it makes sense...it's time to go to bed
600cfm should be ok for that combination. Drilling holes in the blades is a permenant thing - NO going back. Better to use standard tuning procedures, change jets, etc.
Melting Slicks
Joined: Dec 1999
Posts: 2,116
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From: Mid West
Cruise-In III Veteran
Do you have the optimum set of rods installed? Maybe try ones with larger "cruise" sections, but with still the same power section as your current ones. This will only effect very low throttle angles.
Also, check to make sure the springs for the rods are allowing the rod to lower so your using all of the "cruise" dimension. You'll need a vacuum gauge for this.
Also, check to make sure the springs for the rods are allowing the rod to lower so your using all of the "cruise" dimension. You'll need a vacuum gauge for this.
