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SVT Shelby GT500
Need help/advice on what to do about a vacuum issue after JDM cam install
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<blockquote data-quote="genesmob" data-source="post: 15617502" data-attributes="member: 126984"><p>With large throttle bodies, it sometimes becomes necessary to adjust the screw on the tb. Don't just guess at it. View a live monitor and go up or down a percent at a time with the key on/motor off. If the car has a hanging idle, surge on decal a percent or two less can make all the difference in the world. If the idle drops too bad on decal or wants to stumble from too low of rpm then recovers, adding a percent or two can cure it sometimes. Ive used this method on a twin 67mm, an FRPP mono and a whipple 170mm elliptical and I have Jdm ss cams. More tuning is still required sometimes but this is makes life much easier when tuning. As these TBs get bigger, a percentage of opening is a lot larger airflow difference than the stock TB.</p><p>A standard setting on them isn't always ideal.</p><p></p><p>As far as idle vacuum, one way to increase it is to add idle timing which will reduce throttle opening to hit target idle. This will increase idle vacuum for a given idle rpm.</p></blockquote><p></p>
[QUOTE="genesmob, post: 15617502, member: 126984"] With large throttle bodies, it sometimes becomes necessary to adjust the screw on the tb. Don't just guess at it. View a live monitor and go up or down a percent at a time with the key on/motor off. If the car has a hanging idle, surge on decal a percent or two less can make all the difference in the world. If the idle drops too bad on decal or wants to stumble from too low of rpm then recovers, adding a percent or two can cure it sometimes. Ive used this method on a twin 67mm, an FRPP mono and a whipple 170mm elliptical and I have Jdm ss cams. More tuning is still required sometimes but this is makes life much easier when tuning. As these TBs get bigger, a percentage of opening is a lot larger airflow difference than the stock TB. A standard setting on them isn't always ideal. As far as idle vacuum, one way to increase it is to add idle timing which will reduce throttle opening to hit target idle. This will increase idle vacuum for a given idle rpm. [/QUOTE]
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Need help/advice on what to do about a vacuum issue after JDM cam install
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