Weber Main Jet Sizing Question for 2.2S Motor - Help Please!
 

I have a problem with my S spec motor cutting out at 5,800 revs and am trying another item on my list to fix it. Here is what I have:

2.0 E case
2.2 S pistons and cylinders
S cams and crank
2.0L 67S heads
Weber 40IDA carbs
Rebuild has only about 4,000 miles on it.

Checked and verified in spec:

Correct S dizzy rotor
Float levels (they were a little low and after adjusting them seemed to help the problem slightly)
Fuel pressure
Timing
CDI box
Carb filter screens clean

I am going to try changing the main jets to see what that does. I currently have 135 jets in there and am going to try 145. I have searched and researched and cannot locate the book main jet spec. Does anyone have the correct main jet number that this setup might use? Any help with jet size and further diagnosis would be most appreciated. Thanks.

Scott:

A few questions if I might:

1) What size main venturies do you have?

2) Emulsion tubes???

In-tank filter screens get plugged up from either rust or contamination from the gas stations where you filled it. Pull the sending unit and have a looksee in there at the bottom; you'll see the screens.

Check fuel VOLUMES,..........the pump should provide a quart in 45 seconds.



On this subject,....here is a Cardinal Rule: Never buy gas from a station that is being resupplied as that stirs up all the crap in the underground tanks and goes right into your car. These need to settle for a hour before its safe to refill your car. Quite obviously, you cannot tell if the tanker truck just left before you pull in so ask the attendant.

"Quite obviously, you cannot tell if the tanker truck just left before you pull in so ask the attendant".

what's somali for "how long since the truck left?"

LOL,..Now THAT, dear John is truly the $64K question,....:) :)

Although not convenient for many, I pretty much buy fuel from the same two Chevron stations and so I've observed when and how often they get resupplied to avoid such problems. When on the road, its a crapshoot.

Thats why I recommend FAR more frequent fuel filter changes (both of them) than most people recommend. :)

Steve,
Good suggestions on the fuel volume and tank screens. I just assume that the fuel volume is OK since it runs great at all other revs, it just falls off as if rev limited at 5800 consistently. I also assume that the fuel tank is clean since I have not seen any sediment in the fuel filters, carb screens, ect. But, I will have a look see. I am not sure on the venturi size - how specifically do I measure that? Also, I don't have a Weber book, so need some help IDing the emulsion tubes. Thanks.

On a potentially related note, when I stop the car, it idles at 2,000 and slowly drops back to 1,000 over a 20 second period (roughly). Could the problems be related? Maybe a distributor in need of a rebuild? A fellow longhooder pointed that out to me as a potential problem that he had with his car before.

Scott:

Call me,...:)

Steve, not sure if you are still subscribed to this thread, but thanks for the information last Thursday. To clarify, I have the blue top cylindrical Facet fuel pump, which is the highest volume pump they make. I checked pump volume and it pumps about 1/2 gallon of fuel in 45 seconds - pretty adequate I would say. I am going to check the other carb specs and I am confident that they will be correct (F3, 180, and 32mm). Pressure is showing 3.7ish on my somewhat hard to read engine compartment gauge.

Could it be that the coil is breaking down and not giving good voltage at higher revs? I thought that would be a pass/fail type of situation where it is either good or bad. I am going to check the points to see if they are OK and in spec. Probably just order up new ones along with a condensor just to try and have spares. Do you think plugs could a culprit? I may just replace them to have a baseline there too.

I will post my findings as check off my list.

Hi Scott:

LOL,..You know how I feel about Facet fuel pumps; all of them. :)

Coils, like CD boxes, can be intermittent and fail under load but I would make sure that the rest of the ignition system is in perfect shape. This means plug wires, connectors, plugs, points, cap & rotor.