Hello,
I’ve been lurking on these forums for a while trying to learn all I can about Weber’s. I’ve got a 289, currently in a Mustang but will hopefully be making its way into either an FIA Cobra or a RCR GT40 in the next couple of years. In the meantime, I want to put 48 IDA’s on it, and I’m at a bit of a loss on where to start.
First, specs:
1965 289 bored 4.030”, stock stroke (292cid), 9.6:1 compression
AFR 165cc Heads 1.90/1.60 valves
220° @ 0.050” duration, 0.512” lift 110° LSA hydraulic roller cam
Headers into race muffler, full exhaust
3.89:1 rear axle ratio
Lives near sea level
So, I’ve got two calibrations that I’ve stumbled upon for combinations very similar to my own, but they’re vastly different. Which one should I go with?
The first is from a 289 in GT350 Mustang with very similar compression, cam, and cylinder head specs. It’s from a 10 year old Mustang Monthly magazine article, but it seems to jive with what I’ve read so far in the books:
37mm Venturis
F7 Emulsion Tubes
155 Mains
210 Air Correctors
60 Idle Jets
120 Idle Jet Holders
The second calibration is what Redline/Weber (who I’m buying my carbs from) recommends as a baseline for a 289/302 V8:
40mm Venturis
F7 Emulsion Tubes
170 Mains
170 Air Correctors
65F10 Idle Jets
100 Idle Jet Holders
When I asked about the magazine baseline, the fellow at Redline said that a lot of the difference was based on how much gasoline has changed, and how much that effects tuning. This WILL be a pump gas motor. Is there anybody out there in the GT40 collective that would be willing to weigh in on these two vastly different approaches?
Thanks for reading!
Casey
I’ve been lurking on these forums for a while trying to learn all I can about Weber’s. I’ve got a 289, currently in a Mustang but will hopefully be making its way into either an FIA Cobra or a RCR GT40 in the next couple of years. In the meantime, I want to put 48 IDA’s on it, and I’m at a bit of a loss on where to start.
First, specs:
1965 289 bored 4.030”, stock stroke (292cid), 9.6:1 compression
AFR 165cc Heads 1.90/1.60 valves
220° @ 0.050” duration, 0.512” lift 110° LSA hydraulic roller cam
Headers into race muffler, full exhaust
3.89:1 rear axle ratio
Lives near sea level
So, I’ve got two calibrations that I’ve stumbled upon for combinations very similar to my own, but they’re vastly different. Which one should I go with?
The first is from a 289 in GT350 Mustang with very similar compression, cam, and cylinder head specs. It’s from a 10 year old Mustang Monthly magazine article, but it seems to jive with what I’ve read so far in the books:
37mm Venturis
F7 Emulsion Tubes
155 Mains
210 Air Correctors
60 Idle Jets
120 Idle Jet Holders
The second calibration is what Redline/Weber (who I’m buying my carbs from) recommends as a baseline for a 289/302 V8:
40mm Venturis
F7 Emulsion Tubes
170 Mains
170 Air Correctors
65F10 Idle Jets
100 Idle Jet Holders
When I asked about the magazine baseline, the fellow at Redline said that a lot of the difference was based on how much gasoline has changed, and how much that effects tuning. This WILL be a pump gas motor. Is there anybody out there in the GT40 collective that would be willing to weigh in on these two vastly different approaches?
Thanks for reading!
Casey