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intial jetting recomendation for PMO's
78 Euro 911SC
stock pistons and cams with plans to swap cams out in the future to something better suited for carbs SSI's with dual in and dual out muffler (stock dual in muffler that has been modded to "sport" muffler) my initial thoughts was to go with the 40mm PMO's but then talking to a vendor they said I should go to the 46mm PMO's and use 36mm Chokes to get them down to what the 40's are but I would then be able to take advantage of the properly sized 39mm intake manifolds for my engine so what should my initial jets be so I can fine tune from there. I live in the charlotte nc area - so elevation is some where between 600 - 850 above sea level with the occasional trips to the mountains and coast so anywhere between 0 and 4500 is the the range I will use it for some autocrosses from time to time to have some fun. thanks in advance for the advise
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78 Euro 911sc Targa 03 Hayden SCWDP Last edited by osidak; 06-02-2025 at 11:34 AM.. |
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That's a pretty common configuration. Have you done a search on this forum for something like "SC Weber Jetting"? I remember a similar discussion a decade or two ago on this subject. At the time, I pulled together a spreadsheet which I posted of a large number of jet settings with engine configuration and results. I just can't place my hands on the spreadsheet right now.
The nice thing about Pelican is that all of the knowledge is still on the site.
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John '69 911E "It's a poor craftsman who blames their tools" -- Unknown "Any suspension -- no matter how poorly designed -- can be made to work reasonably well if you just stop it from moving." -- Colin Chapman |
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i will search for that thank you
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78 Euro 911sc Targa 03 Hayden SCWDP |
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Bringing this back to the top as I haven't been able to find anything that has been overly helpful by searching the site
best I could find is this using 46mm PMO's choked to 36mm on a '78 3.0liter with SSI's (recap from above) 36mm Chokes 145 Main Jets 185 Air Correction Jets F11t Emulsion Tubes 55 Idle Jets 0.5 Float Check Valve What are the thoughts on this?
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78 Euro 911sc Targa 03 Hayden SCWDP |
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This setup looks like a good base. You will need to drive it and record the AFR numbers to see where you're at.
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83' Coupe - Ex-RaceCar 77' Targa Narrow Body - SC powered Copper Brown Metallic |
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Do I need to also get these to plug the injector holes
PM-O133-6 https://www.pelicanparts.com/More_Info/PMO1336.htm?pn=PM-O133-6&bc=c&SVSVSI=0567
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78 Euro 911sc Targa 03 Hayden SCWDP |
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