Webers or CIS

[jess p]

My car is an 81 SC with an 80 engine 3L SC. I have the original CIS system as
well as 40 mm webers. I have a 73 exhaust from a 911 2.7 as well as a header
set measuring about 1.618 in outside diameter.

Do I need to change the pistons for this carb application if I decide to switch to
the carbs. Can I keep the original distributor.

Thanks in advance

[1QuickS]

First off I think the 1.618" dia headers are referred to as 1 5/8" and are definitely too large for a 3.0SC. If the "73 exhaust" is a muffler then this is probably OK.

You can put carbs on your engine without changing pistons; I believe the distributor needs recurving. There are quite a few posts in this forum regarding this topic.

[Fixer]

Try the headers they will be fine. You are going to have a fast SC with those Webers!

[James Brown]

if you put that mixture together that engine will be so responsive you will go wooooooooo! however, there is some more hp in there to get by matching the intake, jetting, and exhaust system. ignition curving will add more hp than all the rest and new cams and pistons will make you cry! If heat is important than yes use the original exhaust (or a new SSI set) or 1 1/2" headers . good luck!!
the sound is worth all the work IMHO

[advtracing]

Just done the swap and looking forward to a much better car

[Vin-barrett]

Originally Posted by jess p

Can I keep the original distributor

I have a late SC like yours. Your distributor won't work but I did run the early SC distributer with OK results until I installed the mechanical advance distributor from JBracing. It comes with all different advance springs to mess with as well as adjustable advance. It's built on a Mallory advance mechanism. This part made a big difference in the end result of the carbs.

I also recommend Paul Abbott in the post above, he made these carbs look like jewelery. What he started with was pretty ugly... Car runs fantastic.

[Joe Bob]

Simply putting carbs and headers on a 3.0 is a short change.....cams need to be upgraded to get the fuller potential.

"I" would consider cams, modern EFI/ITBs and headers.

[redturbo911]

What does it cost to get a set of carbs for your car 3.0 sc 1980 I have the same motor and interested in doing the same. Thanks keep us posted would love to see what you do.

[al lkosmal]

Originally Posted by jess p

My car is an 81 SC with an 80 engine 3L SC. I have the original CIS system as
well as 40 mm webers. I have a 73 exhaust from a 911 2.7 as well as a header
set measuring about 1.618 in outside diameter.

Do I need to change the pistons for this carb application if I decide to switch to
the carbs. Can I keep the original distributor.

Thanks in advance

Just changing from CIS to Webers and the early exhaust will provide a nice difference, at least in sound and throttle response. It will feel like a significant increase in power. Getting the dizzy recurved should be the next step. You already have the parts...go for it.

After driving it around in this state of tune for a year or so....you'll want more.....or you can wait until you need a rebuild and then dive in and go whole hog with cams, pistons etc.

This is the progression my 1st 2.7 took.

1. Drive it stock, CIS with stock exhaust
2. Upgrade to SSI's and Dansk sport
3. Webers
4. Drive for a year
5. rebuild with JE 9.5:1 pistons, E-cams, SSI's, Dansk 2in-2 out, Webers, etc.

and down the slippery slope we go..........pay me now or pay me later.

It's fun....don't check the receipts

regards,
Al

[jess p]

WOW

Great responses, I am going to go for it. Thanks everyone

[maui44]

It's nice to read about things you can do outside California and not have any smog issues to worry about.

[patssle]

Webers sound better, look better, respond better, and are easier to work on. IMHO of course. Gas milage isn't as good, but I don't drive a classic Porsche for fuel milage - I drive it to enjoy.

Here's my before and after: http://imgur.com/7wjmh