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-   -   intial jetting recomendation for PMO's (http://forums.pelicanparts.com/porsche-911-technical-forum/1178575-intial-jetting-recomendation-pmos.html)

osidak 06-02-2025 06:16 AM

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

jluetjen 06-02-2025 04:29 PM

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.

osidak 06-03-2025 02:17 AM

i will search for that thank you

osidak 06-18-2025 11:55 AM

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?

Nditiz1 06-18-2025 12:03 PM

This setup looks like a good base. You will need to drive it and record the AFR numbers to see where you're at.

osidak 06-25-2025 11:37 AM

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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