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			Join Date: Mar 2011 
				
				
				
					Posts: 27
				 
                
				
				
				
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				Jetting weber IDA's for 2.5 engine
			 
			
			Hello, I please ask the advice of you experts to setup my 40 Ida webers 
		
	
		
	
			
				Here are the details 2.5 engine with 86mm JE 9.7:1 compression, 35mm intake and exhaust ports, 46 I and 40 E valves, E profile camshafts, bursh exauhust 7000 rpm maximum I live in Mexico City at 7,200 ft above sea level The car is a hot street car and will have little track days Thanks Eduardo Last edited by Mexicoearly911; 08-27-2015 at 07:51 AM.. Reason: Information missing  | 
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			 Registered 
			
			
		
			
			
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				Location: Clayton NC 
				
				
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			Contact Paul Abbott at  info@performaceoriented.com. Paul is THE Weber guru.
		 
		
	
		
	
			
			
		
		
		
		
		
			
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	gary 70T coupe forever almost done 88 Carrera Targa diamond blue  | 
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			Thanks Gary 
		
	
		
	
			
			
		
		
		
		
		
		
		
	
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			 Under the radar 
			
			
		
			
				
			
			
			Join Date: May 2007 
				Location: Fortuna, CA. On the Lost Coast near the Emerald Triangle 
				
				
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			My motor has nearly the same specs as yours, except I am running 8,5 CR.  Mine is a SS 2,5 with a 66mm stroke and a 90mm bore. 
		
	
		
	
			
			
		
		
		
		
		
			32mm venturis 135 main jets 65 idle jets 110 idle air 170 air correction With your CR and altitude perhaps you could start one size smaller on both the idles and mains. Only way to know for sure it to get it on a dyno. 
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	Gordon ___________________________________ '71 911 Coupe 3,0L outlawed #56 PCA Redwood Region, GGR, NASA, Speed SF Trackrash's Garage :: My Garage  | 
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			Just finished rejetting a set of IDTPs for a Jerry Woods built 2.5 with GE60 cams for use at 6000ft.  I converted the IDTPs to IDA specification & re-jetted with a happy customer (vintage 911 & 935 racer): 
		
	
		
	
			
			
				
					
 I recommend for you, since you already have them: 
 Per Trackrash, you will want to drive the car to evaluate transition onto the main circuit and if possible a dyno run to validate top RPM/power mixture. It is not necessary to perform a dyno run (dynos are easy to access today but jetting was successfully accomplished before they were so commonly available) but there is a process to be performed. The 34mm venturis may be a little big for your E-cams so per Trackrash the 32mm venturis with 130 mains would be good. It appears you are using Filtron filters (non-OEM air cleaner) so 170 main air correction jets should be used in lieu of the 180 jets. All of these variations will get you close to good but you will want to perform some AFR testing to confirm. 
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			Paul Abbott Weber service specialist www.PerformanceOriented.com Last edited by 1QuickS; 08-27-2015 at 10:13 AM..  | 
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| Tags | 
| 2.5 liter rebuild. , 40 ida , weber jetting |