Weber conversion questions

flash951 · 06-18-2011, 06:11 PM

I have 2.7L fitted with webers and a carb fuel pump in front and a regulator in the engine compartment. I have 2.7S CIS cams.

Questions:
Fuel filters, where should I place them, one before the pump in the front and one in the engine compartment before the regulator?

Distributor, original ok?

Spark plugs?

Anything else?

Joe Bob · Joe Bob's Garage

The cams and dizzy are CIS. Not an optimal setup. Going with a hotter cam and recurvizing the dizzy would be advised.

The filter placement seems to be OK. Depending on the fuel pump I would use filters rated for the pressure it puts out.

flash951 · 06-18-2011, 06:30 PM

Where can I buy rated filters? What cam is hotter? The S carb cams will not fit the stock 2.7L without the 2.7 RS 35mm intake valve?

Joe Bob · Joe Bob's Garage

Are you still using a Fuel Pump that came with the car or one that is designed for carbs?

Cams....20/21 or 964 grind cams. Check with a cam grinder to see if they use yours.....

flash951 · 06-18-2011, 06:45 PM

I use a carb fuel pump and my carbs has been jetted and adjusted so the engine runs clean all the way. I have the CIS exhaust and Dansk 2 in 1 mufler. My fuel pump is maybe to small and I want to change it to the Red Facet pump I think.

I currently have no fuel filters and original distributor.
I have original spark plugs.
Dizzy, what is it?

Joe Bob · Joe Bob's Garage

Dizzy=Distributor

Going with SSI, Dansk or early type heat exchangers helps a lot. Carbs run on low pressure, like 4.5 psi. US delivered CIS heat exchangers are typically one in to the muffler. May be different in Europe.

flash951 · 06-18-2011, 07:06 PM

I have the heat exchangers with two into the mufler, one seperat exchangers (early type) on each side. I ment SSI of course, lol.

Where do I buy/get the stuff? Cams? E-cams fits directly?
Where do I get the recurved dizzy?
What about spark plugs?
Anything else that I should do/change?

Joe Bob · Joe Bob's Garage

Same plugs, NGK or Bosch.

Dizzy shops in Europe....I guess a google for shops that specialize in Porsche. Cams as I mentioned a machine shop that specializes in Porsche. One shop may be able to recommend another.

The stock CIS cams WILL work, but you get better perforamce AND mileage with proper cams. My 3.0 was amazing with a 964 cam profile....still a fuel injection cam but more agressive than the 3.0 cam it replaced.

It's best to see if you can find a shop that will use your old cams and build/regrind to profile suited to your use. Better cost and less modification. For example NEW 964 cams have a lobe for power steering that needs to be machined off.

flash951 · 06-18-2011, 07:25 PM

Thanks, I check that one up.

Eagledriver · 06-18-2011, 08:35 PM

Your dizzy is fine. Just advance it to 30 degrees at 6000RPM. The rest of the engine is fine as well. You can get a little more power with different cams but you'd need different pistons to do much with the cams. Unless you are racing it's not worth the money. You should be close to 200 HP with your set-up. Enjoy your car.

-Andy

RoninLB · 06-18-2011, 08:54 PM

I dialed in the old stock dizzy to 35 BTDC with a stock 8.5:1 compression engine and it was fine

flash951 · 06-19-2011, 02:59 AM

My setup right now has only 171 HP? The Weber needs overhaul and with more time spent on tweaking the adjustment the gay told he could pull out 180 HP from it.

Will the adjustment to the dizzy increase HP?

Is it recommended to fit a fuel filter between the tank and the pump in addition to one filter before the regulator?

Eagledriver · 06-19-2011, 08:26 PM

Is that power at the wheels. 171 at the wheels is about 190 at the flywheel. 35 degrees on the advance seems to be about maximum power for these engines. 171 at the flywheel is close to what you should be with stock CIS and smog exhaust.

-Andy

flash951 · 06-19-2011, 11:39 PM

I have 171 at flywheel.
The dizzy is not adjusted and has stock configuration.

flash951 · 06-20-2011, 11:51 AM

What about the vacum tube on the dizzy?

Eagledriver · 06-20-2011, 07:07 PM

The vacuum is a vacuum retard function for smog. It retards the timing about 5 degrees at idle. You can use it or leave it disconnected. It has little effect other that low power and idle. If you have it connected to an intake manifold, you will have a more retarded timing at idle. The factory spec is 5 degrees ATDC with the vacuum connected at idle. I would try 0 degrees with it disconnected. In any case check for 30-35 degrees of advance at 6000 RPM. If you don't get 30-35 degrees then adjust your idle ignition timing until you do get 30-35 degrees at 6000 RPM. I think I found that 5 degrees BTDC at idle gave me 33 degrees of advance at 6000 RPM on my 2.7 (now long gone).

-Andy

flash951 · 06-21-2011, 03:56 AM

Thanks for advices, I hope this will boost my power up to 190-200 range as well

yama1 · yama1's Garage

Any updates on your progress with your setup. Getting some carbs for my 74 2.7 with SSi's as well.

flash951 · 11-17-2011, 12:58 AM

I have now delivered my carbs to a specialist shop for restauration. When this is finished, my plan is to take my car to another specialist shop for tuning both the carbs and the dizzy.

OZCarrera3 · OZCarrera3's Garage

You may also require a different bellcrank lever on the gearbox to get the correct movement/throw for the throttle linkages. I had to replace the CIS one with one from an early Carb/MFI car when I installed my PMO's.