Installing Weber Carbs Again
 

I am just about finished installing Weber 40 IDA 3C carbs in my 1981 911SC 3.0. It will have taken me eight days of work! It took three days just to remove the fuel injection system. During this time I have gotten a lot of conflicting advice. No one seems to have written down detailed instructions.
The job can be done with or without a lower pressure fuel pump. Right now I have selected not to install a new pump. To do this requires a pressure regulator and gauge. Just before the regulator the fuel return connects to the main fuel line to relieve the excess pressure. I have installed three fuel filters and placed a PMO fuel bar on the Webers.
One mechanic told me that it is necessary to have the distributor recurved. Others say no.
I still have to reset the timing and synro the carbs. I am not sure yet what to do with timing advance and retard?

Sounds like you are doing everything needed. You should have the dist recurved. 78/9 SC dist had enough advance that they did not need a recurve. Later would benefit. You will not acheive max power with out this but the car will still run well.

I assueme you rejetted the carbs to work with the 3.0 from whatever small displacement motor they came from. that was not listed in your procedure.

You are right, removing CIS takes a while.

I bought a new 2.7RS dizzy that has a faster lower rpm advance. PMO did recommend them before. I guess if your needing a rebuild to make sure they recurve. Pelican Parts should have the RS dizzy for less than $300. In the mean time I'd disconnect the vac unit permanently and start timing at 35deg total.

I'm presently installing carbs using Tyson's tip on Not dead heading the carbs. Therefore a full loop from the front of carb1 to the front of carb2, then to the Holley reg., then to return. Tyson posted a good explain.

Ron, do you have a link to Tysons explanation?

Thanks

I'm not saying this to say that the dead head is NG, only what I'm presently doing. The PMO reg with return is a very good unit. I'll try searching for the Tyson info.

Tysons recommendation on a recirculating fuel system. I guess he uses the Holley reg. I like the idea of a non dead head system.

http://forums.pelicanparts.com/showthread.php?s=&threadid=108871&perpage=20&highl ight=recirculating&pagenumber=1

Here's another good thread..

http://forums.pelicanparts.com/showthread.php?s=&threadid=64605&highlight=regulat or

How much do Webers effect the performance & sound of the engine? (Well I know they look better!) Just wondering....
jt

Re: Installing Weber Carbs Again
 

What did you do with the cams and pistons? The CIS pistons won't work well with carbs, if at all. The compression is very low in the stock CIS system. The profile is different. To get the most out of them you need "S" cams (or have your's reground to "S" specs)as well...

I have not be able to get the new set up to run. I decided to install a new low pressure pump but something is wrong because the gauge does not show any pressure and the car won't start.

how much more HP do you estimate with the new fuel system over the standard CIS?

Hi there..
Performance is best for carbs is if they're part of a cam, pistons, exhaust package. if just thrown on a FI cam and piston engine it'll be ok, but not a big deal. Throttle response fun will be better imho w/ carbs. They do look and sound cool.

Carbs are also cool in a perverted way.
We know that FI is a detailed concise squirt.. I think of filling a bottle w/ gas and pouring it directly into the combustion chamber thru a big tube is what carbs are all about.. I'm not a pro.

and e-mail me so I can send you the info on the BigBig Ride pelican site.

so the pump goes to the regulator. then from the reg to a gauge.

so did you remove the line from the reg feed or the pump discharge to see what happens ?

I posted a couple of pics of my new full loop fuel system.. entertainment

http://forums.pelicanparts.com/porsche-911-technical-forum/165458-carb-plumb-loop-pic.html?highlight=feed