All you need is a compression gauge.
Running a compression test is generally the first step on these things. Don’t expect much in the way of high numbers because compression numbers on the air-cools are generally low; as in 110-120 PSI.
Setting the timing at the 7.5 mark is preferred and this can be done accurately with no timing light. Rotate the engine until the rotor points at No. 1 on the cap with the pulley mark aligned with the crankcase split, loosen the dist. bolts, connect a test light to a hot terminal on the generator, and probe the coil terminal that leads to the dist. Rotate the dist. back and forth until the test light flickers.
That broken valve adjuster would have me concerned as that is just about unheard of. Did you set the valves at zero or did you adjust one cylinder at a time (at .004 or .006 depending upon preference) with the necessary engine rotation after each cylinder?
Did you find any excessively tight exhaust valves while checking lash? These engines can be prone to swallowing a valve at times and a tight exhaust valve can be a sign of impending doom.
Ok, I do not have a compression gauge, but I will make my way to go get one. I am still in the process of acquiring the tools I need for this car.
That is exactly how I timed it, with a test light to 7.5 mark. I set the valves to .006, which is what the manual suggested (the engine was cold when I did so). I rotated the engine accordingly as well.
I did find a few tight valve screws, if that is what you mean, although I do not recall which ones. I am not sure if they were that tight or if the confined spaces, especially the ones towards the rear of the car, were to blame for the difficulty. Could have just had a hard time gripping those screws/nuts.
However, if you mean that the valve adjustment was too tight then I do not think there was anything wrong, but I didn’t check to see how tight they were before adjustment unfortunately. There was some minor leakage but I assume that had to do with broken screw because they have remained relatively clean since replacement.
I have run a compression test, cylinders 2 3 and 4 all check out in or around 120 PSI, however, cylinder 1 came in at 75 PSI. I did a little reading and I have learned you dont really want to go less than 90. So that leaves me with a problem!
Triple check the valve adjustment on #1, just to be sure…
I’ll second the carb cleaning, but remove and clean all of the jets and the internal passages. I’m not sure a float would cause a bad idle but plugged passages or jets would. Might be time to just put in a carb rebuild kit instead of trying to clean everything. There are some very small passages.
Yeah I’m starting to side with the rebuild. I just did the valves putting everything back together now, cross your fingers!
If the valve lash is correct on the low cylinder and the compression remains at 75 then there’s a problem and it could be serious.
With an air-cooled VW the most likely cause would be a burnt exhaust valve due to tight lash. This leads into the issue of a valve job. Exhaust valves are NEVER ground on an air-cooled; they’re always replaced with new. This is due to valve stem stretch which can lead to the valve head popping off and dropping into the cylinder. At 4k RPM that could be quite catastrophic…
Getting into the cylinder heads then delves into the area of case stud threads pulling in the engine block, the cylinder heads needing to be flycut or replaced as these engines do not use head gaskets, etc, etc.
With the engine not running, you might grasp the crankshaft pulley with both hands and push it forward. Now slam it back and forth a few times. If you barely feel any movement and/or heat a slight tick the lower end may be fine. If the movement is very noticeable and you hear a clunk or thunk sound then the engine block is beat out. This means a major overhaul.
Ok so, unfortunately I was not able to test the compression again after I adjusted the valves because I rented the gauge and was returning it. However, the cylinder one valves were a little loose and I fixed them up nice and there is a good sound to the car now, or at least better than it was.
I took it for a ‘test drive’ down to the gas station a couple blocks away. Heres the problem you can start the car in the garage fine and then you can bask in the glory of the car as it sits and runs and idles just great. However, as soon as it is on the road it refuses to coast. I would be coming to a stop light or down a hill put the clutch in and dead. I must have started it 3 or 4 times there and the same on the way back. And this gas station is less than 10 minutes away!
When you cleaned the carb did you adjust the screw behind small triangle on the carb because that could be the problem.
I am in the same exact situation as you. One AMAZING resource I’ve been taught is to buy this book.“How to keep your VW alive.” Worth every penny!!! good luck.
Yes @Alex, that’s a great book. I bought a copy of the original book in the 1960s and it would be a good read even for those not interested in rebuilding their VW and also for anyone wishing to get an insight into all the basics of automobile mechanics… “Be kind to your ass for it bears you.”
Alex this thread has been inactive for 3 years do you really think the person who started it is still around?
Still here, but sadly sold my VW in March 2014 to finance a move to
Ireland. I reassembled the carb twice and still experienced the issue,
however I discovered (with the help of some Samba users, that is) that the
problem was a little crescent shaped float in the carburetor that was on
backwards, explaining why it liked to die going downhill. Flipped it, did
points, valves, and the like and everything worked out swimmingly!
Now, just need to get another VW!
Alex this thread has been inactive for 3 years do you really think the
person who started it is still around?
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I am in the same exact situation as you. One AMAZING resource I’ve been
taught is to buy this book.“How to keep your VW alive.” Worth every
penny!!! good luck.
I typed for others to see it and chime in. With VALUABLE info.