Stromberg WW base gasket leak

[Indy998]

Hello,

this is my first thread on the B-Bodies forum although I've been using it quite a bit in the past. I live in the Stuttgart area in Germany where classic Mopars are an almost common sight, at least in summer. My ride is quite unique though - a plain jane 67 Belvedere II 4-door in medium metallic blue, powered by a stock 318. I found it at the Carlisle swap meet in 1994, an unrestored one owner car with 18700 miles on the clock. I've added about the same amount since, and I promised myself to never let her go. Now here's my problem.

Since day one there has been a wet spot on the intake manifold in front of the carb. Over the years it became more noticable, and slowly but steadily the fuel consumption got worse. I rebuilt the carb twice, and the throttle shaft still feels very tight. However, the leak problem never disappeared. A couple of years ago I bought a remanufactured carb. Right away it was clear that it was in much worse condition, basically everything was loose. I mounted it anyway, but the engine never ran properly, the mixture being way too rich. I had a very experienced garage trying to set it up, but they gave up too. So the old carb went back on. On closer examination I noticed that when I operated the throttle with the engine off, immediately the base gasked would get soaked with gas. With the engine running, this doesn't happen.
I tried two gaskets on top the other (both made from black card board), I tried the old one together with one of the new ones, but the leak never went away completely. It did get better, but it just doesn't stop.

Sorry, this quite a bit of text for a small problem! I'll appreciate any help.

Best, Mat

 

[rlem1977]

What carduretor(s) are you using?

 

[Indy998]

The original Stromberg WW 2-barrel

 

[rlem1977]

You can call either of these two and discuss a refurb. They are purportedly experts in your carburetor:
Dave Thibeault (U.S. Tel #978-897-3158) http://www.studebaker-info.org/Vendors/tbow/tbow0513b.html
Daytona Parts Company https://www.daytonaparts.com/
Hope this helps

 

[Indy998]

Excellent, thanks!

 

[RJRENTON]

Indy,
I had a '67 Plymouth with a Stromberg WWC3 2bbl carb on a LA318 engine. The Stromberg WWC3 carb has 2 removable main jet access wells, sealed to the fuel bowl with VERY thin copper crush washers. Perhaps someone removed these acess wells and did not replace these crush washers. BTW...you MUST have the Stromberg jet removal tool (looks like a deep well socket - 3/8" drive) to remove the jets. There is an accelerator pump transfer passage plug that is also been known to seep/leak gas onto the manifold. Most of the early 318 engines used the Stromberg WWC3 carb. Although sometimes these engines came with 1 1/4" CARTER BBD carb (Ball & Ball downdraft). The Carter carbs have the fuel inlet fitting on the FRONT of carb; the Stromberg WWC3 carbs have the fuel inlet on the SIDE of carb.
I would guess the Stromberg WWC3 carb jet access fitting crush washers are missing or damaged.
Bob Renton

 

[Indy998]

Hey Bob,
Thanks very much! This is the personal experience I'd been hoping to get as over here no one knows about stock parts anymore, everybody has aftermarket stuff theses days. Is this the washer you mean?

Mat

 

[RJRENTON]

Hey Bob,
Thanks very much! This is the personal experience I'd been hoping to get as over here no one knows about stock parts anymore, everybody has aftermarket stuff theses days. Is this the washer you mean?

Mat

View attachment 602187

Mat,
YES...these are the copper crush washers I was referring to. Item 2 are the main jets that are removable. Item 1 are the main nozzles that extend into the venturi. This is how fuel is introduced into the air stream.
If you are UNSUCCESSFUL in stopping the leak, consider switching to the 1 1/4" Carter BBD carb. You will need to change to the Carter divorced choke assembly along with the fuel inlet tube. This is an "S shaped" 5/16" tube with an male inverted flare fitting and connects the fuel filter. The air filter will fit, the base gasket will need to change to the Carter gasket. You may need to readjust the kick down link slightly. The Carter carb uses fixed orifice jets and vacuum controlled metering rods, which are also hard to find. The Stromberg WWC3 carb was eventually replaced with the Carter design. Air flows were approximately the same .
Let us know how you make out.
Bob Renton

 

[Indy998]

I'd like to keep the Stromberg if possible as it is the carb that came with the car and it is extremely responsive. But thanks for suggesting the Carter and supplying me with the necessary information! I need to get hold of the special tool then for removing the main jets. I guess I could also take a look at my rebuilt carb and mix parts if necessary. Actually, with the super low mileage though I wonder whether the carb has ever been apart at all (all I did to it was changing gaskets and things).

The one thing that really makes me wonder is that retightening the carb to manifold mounting bolts reduces the leakage, plus the fact that with the engine not running the fuel which I guess comes from the accelerator pumps soaks the carb base gasket completely until you see a puddle around it. As soon as there's vacuum with the engine running the fuel gets sucked in again.
So I was wondering if the black card board gasket that came with the rebuilt carb is the the right one or whether it should be made of a different material.

Cheers, Mat

 

[RJRENTON]

Mat,
My recollection of the base gasket is its approximately 1/8" thick made from a non-porous hi temp material that resembles a teflon based material. BE EXTREMELY CAUTIOUS in tightening the mounting bolts/nuts. Go slowly in a crossing pattern. I always spray the new gaskets with a silicon spray to prevent the gasket from sticking to the manifold or carb. The carb base can be distorted if tightened unevenly causing an vacuum leak.
Bob Renton

 

[Indy998]

Thanks for reminding me, but yes, I am careful when tightening these bolts. Which I did today, mounting bolts were fine but the 6 top cover screws weren‘t. All of them a bit loose. Pic shows carb before I wiped it off. Let’s see tomorrow after the next drive!

 

[Indy998]

Here‘s what happens when I operate the accelerator pump a few times with engine not running. See soaked gasket.

 

[RJRENTON]

View attachment 603266 Here‘s what happens when I operate the accelerator pump a few times with engine not running. See soaked gasket.

Mat,
Not to be redundant , but have you taken the carb apart yet?
If you take the carb off of the engine and remove the throttle plate assembly from the fuel bowl assembly there MAY be an internal fuel transfer passage (visable only after separating the throttle plate assembly from the fuel bowl) passage plug that is leaking. Example .... the accelerator pump transfer passage from the pump well to the passage that connects to the accelerator pump discharge check valve drilling (how the fuel gets to the discharge check valve in the main body). Its possible that there is a cracked body or a leaking plug. Remember the discharge check valve and accelerator pump discharge nozzles offer a restriction during operation and any leaking drilled passage plugs will leak due to the increased pressure (compared to atmospheric pressure). If dissembling the carb, spray all gaskets with silicon .... it helps sealing...and keeps gaskets from sticking. Keep us informed as to your progress.
Bob Renton

 

[Indy998]

No I haven't, next weekend!