So I finally got my Pertronix back and I'm going to get my motor running again. I went from a stock 1.7 which had the webers when I got it , to a short stroke 96mm 1911cc (66mm stroke) motor. Befor the motor ran a little rich, so I am going to need to re-jet the carbs for the new displacement. I'm running machined 1.7 heads.

I wanted to see if anyone out there is running this set up and can recommend what jetting to use, I don't want to play the guessing game.

Lots of great info here. http://www.aircooled.net/vw-carburetors-jetting-102/

Typically you baseline your jetting for the mains off the venturi size. Idles are typically in the 55 range for a Weber if memory serves. The link above will give you all the info you need! A wideband O2 gauge is really nice to have too...

Chris, I have a decent assortment of idle and main jets at home from when I jetted my old 2143. Let me know what you are looking for, and I may have a set..I bought a lot of jet sizes trying to get that motor tuned.

Can't help on jetting recomendations without venturi diameter...

We don't know the venturie size as mentioned ? but let me suggest they are big carbs for your displacement,the only solution is to drop venturie size to improve vacuum loss down low which really is where you drive mostly.
You will make good power up high but the downside will be a soggy bottom end and jetting will drive you nuts cause you will never have a good ideal setup or sweet spot.
Not really nice to drive with this setup and fuel consumption can be very heavy not to mention potential damage to the engine with an overly rich condition.
I have 36mm Dell's for my stock 1.8 and 1911 both are 32mm venturies,Jake Raby has talked about this setup being fine for up to 2056 from memory,then go to 40mm carbs or 34mm vents with the 36's from there.
Your low speed jet needs to be a 55 as a baseline,some run 60's but that's a little fat IMO,the rest is up to the individual engine....and carb size .

44s are a bit large for a 1911, however, you can get new smaller venturis for reasonable $ from CB Performance (I bought some for my 40s for about $8. each).

Thanks for all the input. The aircooled site is great. I found what the general parameters should be on the carb from CB performance.

Click to view attachment

The main thing to see is if these carbs have been "adjusted" or "messed" with, are the ventures stock, what jetting is in there now, etc... (the joys of buying other peoples projects) The hard part is not knowing if the carbs are "stock" in a sense.

So, what about the motor being new and needing to be broken in? I see to test and jet the motor they want you to RUN the motor in the jetting process, but I have not broken in the motor yet...So I should just cruz around with general OK jetting then tune it in later?

Having run 44s on a 1911, I think you will find 28s much more drivable than 36s on the vents. 32s might be the biggest I would go.

Disassemble them and remove the venturis (and jets of course) ... they should all have their sizes indicated on them, however, some people have been know to drill jets to a larger diameter, so it's always good to check them with jet gauges to be sure.


If the motor is new (especially the cam and lifters), when you first start it up, run it up to 2500 RPM for about 15 minutes. When it's cold again, check and readjust the valve clearances.


Oh, and hopefully you filled it with break-in oil? As it's cooling down, drain the break-in oil and let it drain for as long as possible. Inspect the drained oil for metal particles, also a good idea to remove, inspect and clean the sump screen, then refill with regular oil and a new filter (I prefer Brad Penn 20/50).

Wise words Mike,air correctors would need some trial and error it that case,I'am not suggesting they won't work for a minute but drivablity is the key issue afterall.
Over carbed motors are stink to drive unless used on the track or autox.

Years ago I ran Weber 44s on a modified 2L motor (ported heads, 3/4 cam, headers, Euro pistons). The specs pasted above look pretty close. I jetted a little richer, probably because of the engine modifications. I think I ran 145 mains, not sure about the others. You definitely want some way to determine A/F ratio. I used an exhaust gas temp gauge because that was the best option back then. Wide band O2 is the way to go now. You'll save yourself a lot of time and guesswork.

Scott

Chris, once you get your initial jetting in the ballpark, ask around to see if any locals have an A/F meter you can check your mixture with, then, if necessary, re-jet accordingly.

If it will make it up to Harbor City (before the end of the year), we can check it at my shop.

Is is possible to RENT a wideband AF meter anywhere?

http://vwparts.aircooled.net/Innovate-LM-2...band-rental.htm

Well hell ... never thought of Renting mine out.

Hmmm ... extra retirement income

Thanks for all the info. I didn't add a cam, tho I probably will wish I did. It was not really a planned build so I just did the pistons, jugs, and machined the heads with some head work from air flow masters in vista. Maybe it would be worth just having him go though it all so I can get all the numbers and parameters for once and get a base line. I think he has built a few of these motors.

Anyway, I'll look into all your guy's great feed back after the weekend will likely go one of two ways...

OR

P.S. He mentioned he threw a ring in the base of the jug when he assembled the new pistons for compression, should I get what the compressions should be in determining the jetting?

Thanks again!

Once you get it running Chris, you're more than welcome to bring it over to my place. We can play with the carbs for a bit..

My dad and I have gotten pretty good at jetting without the use of a wideband O2 sensor.

Knowing the compression #s would be advantageous, Chris, but you're not lost without them ... especially if Ethan's on your team

That would be great! Thanks! I would really like to learn to do this myself so I can maintain these myself correctly moving forward. I get the Pertronix in this weekend and see how she fairs.