|
|
|
My friends really nice, low mile B-20 '69 1800S with a downdraft Weber 32/36 has recently started gassing her out. I'm not a huge fan of the Webers, since they are tiresome ot set up originally, and tend to get weird after a few years of use.
Don't get me wrong, for people who have lost patience, or control, installing a Weber after fussing with OEM carbs, appears to be a magic bullet. Several years ago she drove across the country with this car, and it performed flawlessly. I've recently noticed that there is a lot of blow-by around the throttle shafts,and she tells me that the gas mileage isn't as good as it was (maybe low 20's versus high 20's earlier). I suggested washing and cleaning out the K&N air filter for a start, and possibly a new PCV from the flame trap, plus a new one-way valve from the brake booster. It's had a big tune-up in recent memory, including a valve adjustment, and plug wires. Car has a Pertronix breakerless ignition installed.
Without being on the scene myself (I'm on the Left Coast, she's on the Right), I can only add a few "red-herrings" from her input, and my recollections;
1.)I seem to remember that compression in one of the cylinders (#4?)was lower than the others. Like maybe 120lbs, versus 180lbs. Not sure, but it was more than 10-15 lbs. Maybe broken piston rings?
2.)There was a valve job, with hardened seats in recent memory.
3.)Car gets pretty even local and highway usage
4.)Car gets premium gas almost exclusively
So, what are we looking at here, a new Weber,
a fresh set of SU HS-6's? Reshafting the Weber?
Suggestions welcome,...
|
|
-
|
|
|
Check the gas tank for leaks.Had same problem with 1800ES every time I topped the tank.Wouldn't go away until 3/4 full.As for the gas mileage, if you have more than a 10-15% difference in compression,rough idle and poor gas mileage result.
|
|
-
posted by
someone claiming to be patrick of montreal
on
Tue Feb 1 06:31 CST 2011 [ RELATED]
|
|
don't know this weber set up but if it has a auto choke I would make sure it is not staying on all the time. That would cause the smell and the hard warm restarts, but in cool weather may allow adequate performance. Some auto choke systems perform poorly in cool weather, while still working fine in cold or hot weather. the time.
|
|
-
|
|
Before you go too crazy with carb. issues, do a compression check.
You're statement that one may have been 120 with the others closer to 180 is suspicious.
It will not run "right" with a bad cylinder. It will run, but just not right and trying to compensate by doing other fixes will be an exercise in futility.
|
|
-
|
|
|
Difficult to advise really as we are already working with second hand symptoms. As said check that everything's buttoned up tight especially as there's been some engine work done recently. Anything other than small "normal" leaks should be fairly obvious, be they fuel, oil or exhaust gas. Test the latter by blocking the exhaust outlet with a cloth pad with the engine running fast. Might have an oil leak dripping on the exhaust, possibly from the sender unit on the block or the speedo cable. Getting it on a lift would help. A stuck choke or leaks from carb gaskets, the pump system might have a leak. The fumes have to get in the cabin somewhere so check the gear lever boot for starters, Also, as the fumes seem to be mainly "gas" it could be from the other end of the car. Check the trunk and see if there are any fumes there from leaky pipes or the sender unit on top of the tank.
|
|
-
|
|
|
update/response to your responses (thanks in advance)
1.) Weber carb has the matching intake manifold and a separate F.I> type exhaust manifold. Didn't try the "tighten everything in sight route yet", although that is SOP.
2.) the smell is really one of unburned, or partially burned fuel. Not exactly raw, as is overflowing carb with stuck float valves, but more of a "fume-y", too rich unburned gas smell like a clogged flame trap, or something like that.
3.) my friend found, on the classic Opel owners site (they must use a lot of Webers, too)a mention of missing phenolic and/or metal heat riser plates or blocks as a cause of poor combustion, and maybe pre-combustion. As far as I know, this set up was bought new, complete w/ manifold and installed out of the box.
I wasn't around to know if it was painstakingly jetted, and or completely dialed in. I've driven it, and it does what an old Volvo does best; charges along, surprising newer car owners left and right! But, now it smells like a stinky old truck!
4.)
|
|
-
|
|
|
Thanks once more for the input and the insights
I have tried to use the BB, both now, and in the past, with an eye to helping others owners deal with similar issues, and to archiving common problems for future reference. I've owned and driven older Volvos since the 1970's, (when I bought my first '67 122 for $125!)Excepting poor maintainance and poor driving habits, the problems they have are often universal. Certain things seem to always come up, caused by age, poor design, mal-adjustment, or all of the above. For example, I hereby challenge you all to find one single long term functioning 1800 (OEM-Smiths) dash clock!! I've had 2 coupes and an ES, and never had one work.
I know I'm making this post difficult by not actually having the car in front of me, but I drove it just last week, and can confirm the symptoms. All of your suggestions have been logical, and I'll have to assume that some of you have had similar problems.
At the moment I particularly like the advice to review the low cylinder reading, and the idea that what I'm smelling could also be a result of a bad seal at the fuel tank. I've had that in the past. What about the heat riser as a source of poor combustion? The one mounted is about 1/2" (13mm) tall, but looks entirely standard to the set up.
To repeat, this is definitely "fume-y", NOT oil, such as a bad valve cover leaking onto a manifold. The engine is pretty tight, as in not leaking oil, still bright red, and clean looking, aside from the aforementioned blow-by around the base of the Weber.
Did I mention that it is often difficult to start when it's been recently driven, e.g drive to the store, come back in 5 minutes, and have to crank it 2 or 3 times?
Also, the car is about to be retired for the winter, so this may become a long term discussion. However, the weather on the East Coast (in Virginia) may hold for another month, so it would be good to deal with this before Pumpkin Time.
Is it time to start rebuilding a set of SU HS-6 carbs for installation in the spring??
|
|
-
|
|
|
The 69 originally came with Stromberg 175CD2 carbs and I can see why they might have
changed away from them. I would have changed to SU HIF6 (or HS6 as second choice).
Either would have been pretty much a bolt-on conversion on the same manifold.
Stinky exhaust usually comes from a mixture that is too rich. If the shafts leak,
it could be that the carb was re-jetted to idle properly which would make the engine
too rich under power, where throttle shaft leakage is much less significant than at idle.
Might also be worth looking to see if the choke mechanism is stuck closed or partially closed.
|
|
-
|
|
|
The B20 uses a flame trap element, not a PCV valve. These need to be cleaned often, and if the engine had some blow-by, then even more frequently. If the element gets clogged positive pressure buids up in the crankcase, oil seals fail.
On the B20 the combined intake/exhaust manifold can rattle free. You should check the manifold nuts and studs every 30k to see if they loosen up. There's a good chnace all it need is a new gasket on the head & downpipe. This is the most obvious cause of the fumes, very unlikely that a throttle shaft will emmit enough gases to smell.
I've had a few of the Weber conversions on B20's, and among their problems, never had throttle shafts fail like on SU's, actually were very reliable. If it is low miles since the carb swap, the problem is not likely due to carb at all. Look eslewhere.
If it does turn out ot be the Weber, it is probably cheaper easier to get another Weber than re-build the one she has.
|
|
-
|
|
|
If you go the SU route, you will have to also change your intake (obviously). I am particularly biased toward SU's but have never experienced a Weber. However, perhaps sourcing the SU's plus a rebuild and comparing that to a complete Weber rebuild, might answer some of your questions???
--
Kent - too much iron, too little time
|
|
|
|
|
