1970 911S motor questions

[jimpollum]

I have been working on a friend's 1970 911S that would not run. The carbs were in bad shape so I started to rebuild them. It has 2 Weber 40IDTP13C carbs. I went looking for information on them and found it difficult. What I did find is all references to the 70 911S say that it should be fuel injected. The engine serial number is 6301796 and it appears to be the engine original to the car. I checked the VIN and the number says it is a 1970 911S. What is not discernible from anything I can find is if this motor was originally fuel injected and converted to carbs, or the carbs were factory installed. Can anyone help? Thanks

[techweenie]

All 1970 911Ss used Bosch mechanical fuel injection (MFI). Over the years, as MFI systems went off tune and mechanics were unable to get them to work correctly, many were replaced by carburetors, which the mechanics presumably understood better. Unfortunately, restoring the correct MFI to that engine is a major task and costly. And you'll be right back to the prior owner's challenge of getting it set up to run right. If you can, it will be worth the effort.

[Grady Clay]

Jim,
Welcome to Pelican
You will find a lot of help here.

First, 6301796 is a mechanical fuel injected (MFI) engine that some PO has installed Weber carburetors from a 914-6.
Unless some changes were made to the carbs, the original configuration is not ideal for a 2.2S

There is hope.

These carbs can be very functional on this engine, given correct settings.
The Pelican Search Function is your first line of discovery.
When you have the knowledge and information, we can help you finesse the settings.


First, what are the current settings?
Those include venture size, main gas jet, main air jet, idle jet, emulsion tube type and the numbers off both carburetors.

You also need to confirm that the engine is still an un-molested 2.2S. Cams and heads being the most important.

Again, WELCOME

Best,
Grady

[jimpollum]

Your help is much appreciated. Since I told my friend (Harvey) who owns the 911S, I have been spending an inordinate amount of time researching details on this vehicle. At first, it appeared to me that a carb rebuild, valve adjustment, and some fine tuning would put the car back in good running condition. New battery cables and electrical connectors were also needed. It was purchased used 15 yrs ago and has sat in a garage most of the time since. The gas in the tank and carbs was really bad so I took the carbs off to rebuild. While disassembling them, several jets fell apart from deterioration, nuts and bolts were overtorqued making them hard to remove, and the bad gas left much varnish and debris. It took much effort and carb cleaner to get them clean. I am not sure that they truly are completely cleaned. I was unable to remove the emulsion tubes so I did the best I could.
Pelican had the rebuild kit but did not have jets in stock and referred me to Pierce Manifolds who did. I ordered what I thought was correct. What is in the carbs now is:

.55 Idle Jets (and new holders)
1.25 Main Jets (and new holders)
1.80 Air Correction Jets
Original Idle Adjusting Screws (are in good shape)
New Float valves (came with rebuild kit)
New Fuel Screens
New Throttle Shaft Bushings
27mm Venturi – original
The numbers on the carbs are at my friend’s house and will need to go there to get them (soon). The gas tank was removed and flushed. I have not found the fuel pump and need to now to see what kind it is, and make sure it is cleaned. The fuel lines were flushed and new in-line fuel filters installed along with as much new fuel line I could replace.
As for the motor, I cannot tell if it has been modified but it looks not to be. The odometer shows 145,000 miles. It ran well a couple of years ago, according to Harvey.
What concerns me is what jets should be in the carbs, do the emulsion tubes need cleaned/replaced and if so, how to get them out of the carb. Also, needed is what the timing should be, and if I can use my regular timing light to get it set properly. I wish I had done more due diligence before trying to fix the car, but I love a challenge. Again, any help is really appreciated. I have some pics that I will post as soon as I can find them

[Steve@Rennsport]

Hi Jim,

Grady is right; you need to confirm that the car still has its original engine since the above jetting package isn't right for a 2.2S motor.

I'd look at the type number, serial number, and measure the intake port diameter at the very least. Pulling a valve cover results in seeing the camshaft numbers to help confirm they are still "S" cams. Note the MFI pump drive as well on the front of the left side cam.

I'd start with:

50-55 idle jets
135 main jets
180 air correctors
32mm main venturies

Make sure you have F3 emulsion tubes in there; remove the air correctors and using a round wooden toothpick, push down and extract the emulsion tubes to have a look.

Properly set up and configured, this car should run VERY well on Webers if they are in good condition and adjusted.

[jimpollum]

I went over to the car today and removed the bottom right valve cover. I was not able to find any part numbers on the camshaft. Can you tell me where the part number is supposed to be? Also, Harvey, the owner, said the fuel pump used to make a whine when it was running, but now it is clicking, and it looks like not much gas is flowing. I am going back tomorrow with a fuel pressure gauge to test it, but it appears it needs serviced or replaced.

[jimpollum]

Here are pix of 1 carb mostly redone. 1 jet broke while putting it back, and another already broke while taking it out. They are replaced now.

[jimpollum]

and a pic of one of the jets