2.2 vs 2.7 Weber setup

[upwardr]

Will a set of carbs from 2.7 be set up similar to a 2.2 as far as jetting goes?
Or will jetting need to be done

[75 911s]

Jets, Air correctors, chokes and Idle jets will all be different. The weber itself can come in assorted variations (IDP, IDTP and IDA) but you will be getting a 40 (so Like weber 40 IDA ---IDA are the best by the way) so familiarize yourself with those if you are buying a set. Don't worry about the little parts is my advice. A lot of these old carbs work so much better with new clean parts anyway. The last three sets of carbs I bought came with mismatched pieces and a some of them were damaged.

There are a couple good graphs here in the forum if you search that show jetting info based on your motor.

[upwardr]

So I installed the webers as set up for the 2.7 and it runs. The cylinders are all drawing 7 to 10 with the Uni tool but 1 cylinder is only showing 2 to 3 and does not change even when adjusting the air correction screw or turning the mixture screw.
What would cause this situation?

[teeitup]

Have you looked at Paul Abbot's website, PerfomanceOriented.com?

[upwardr]

Yes but it doesn’t address this situation.
At least I could not find it.

[Black 993]

Originally Posted by upwardr

So I installed the webers as set up for the 2.7 and it runs. The cylinders are all drawing 7 to 10 with the Uni tool but 1 cylinder is only showing 2 to 3 and does not change even when adjusting the air correction screw or turning the mixture screw.
What would cause this situation?

I would do a compression test on that cylinder...

[75 911s]

The jetting, chokes etc -would be different if the 2.7 was setup correctly. Here's a handy graph:



4.5 is where you want your syncrometer to be at.

Look up "Best lean Prodedure weber" on this forum.

There's also a linkage adjustment tutorial floating around. All your linkage needs to be right or you'll never get this running right.

Do you have a Fuel pressure bypass? Should be no more than 3.5 psi.

If you don't have any of the right parts as outlined above in the chart, remove the webers and totally disassemble them.

The low setting on one cylinder is likely a blocked passage. There's a hidden passage that is notorious for this problem. There should be a few posts on clearing hidden passages here on the forum. It involves drilling out the lead plugs and clearing out the passages.

I have some smaller chokes 30 and 32 I would trade you for the 34 chokes that you have in there. They are too big for the 2.2.

If you check my Instagram, and go to my profile, you'll see saved stories. One of them shows the hidden passage on the weber that could be the issue to your low vacuum on one cylinder.

[upwardr]

Update on my carb.

I removed the carb and found the tiny Allen screws in the throttle shaft coupler were loose.
Tighten up and begin to switch up jets and chokes from original carb to new set.

Thanks for the help on this, and I hope to ger this motor running properly.

[upwardr]

Both sets had F1 emulsion tubes but recommended are F26. will F1 work ok?

[75 911s]

Larry,

The F1 Emulsion tube is fine. It's what would have come on the T.

For more information on this check out Paul's guide. Scroll down to see the different Emulsion tube details.

Ultimately road tests are your friend. There are a lot of factors that change given individual engines and altitude etc.

I would also recommend getting a fuel level gauge. I don't think our host carries it anymore, but you can get one here. Don't underestimate the importance of getting the fuel level in the bowls height level set correctly.

Good luck.

[upwardr]

Thanks for your help.

Yes I have a fuel gauge bypass set to 3.5 pounds
I have had a compression test and seems okay.

I do have a fuel glass float gauge and fuel is to the upper line.

One thing I notice is left bank the air meter stays pretty steady but the right side the meter fluctuates 1 1/2 up and 1 1/2 down so hard to know what Number we are to use.