Problems with my 12a powered vw Beetle
 

hey guys, I recently bought a 1968 VW Beetle powered by a 12 rotary. I didn't even know rotary engines were a thing until I bought this Beetle, but I'm slowly learning more and more. Now the beetle had been sitting for a year, and when I bought it the engine would turn over well, but would not start. To start, I rebuilt the Holley carburetor. It was my first rebuild, but I believe I did it correctly. After re-installing the carb, the engine still would not start, but when I had one of the spark plugs pulled out and grounded to the block to test it, the engine started when I turned it over, and shot up to 7000 rpm. It was exciting at first... but now i cant seem to get it to idle at anything lower than 7k. I've adjusted the idle screws on the carb, even tightened them all the way, but it keeps spinning out of control! I don't know much about rotary engines, but when I was testing the spark plugs, the sparks seemed weak, so I was thinking the plugs may be fouled, but why would that cause the engine to idle at 7k? I've called a rotary shop in MD, and the owner told me with supreme confidence that I have a massive vacuum leak. I don't know what to think, so I'm hoping someone here can steer me in the right direction!

welcome to the board. :)

7000 RPM? first of all, that's not an idle. the throttles are wide open or pretty close to it. i completely disagree with the vacuum leak theory, too. as i said, for that kind of RPM, the throttles are open. this is an issue with the carburetor for sure. the first thing that comes to mind is do you have return spring on the throttle? the second thing would be to look for binding (cable, pedal, linkage, bent shaft, etc.).

at this point, there is no telling what your problems are. until you can get the engine to run with the throttles closed (at any speed), you have no hope of tuning this thing.

Thanks for the welcome man!
I'm new to rotaries, and still a rookie mechanic anyway, so i wasn't sure what to think about all this. Right now I've got a holley 4160 carb, and when I put it back on I did re-attach the return spring. I will have to check all of the throttle linkage, it had been sitting untouched for a year before I first smashed the gas pedal while trying to start it, so I'd say theres a decent chance that it's stuck... But the way I see it, if my engine can run at 7000rpm, then my first carb rebuild must have been a resounding success! and at this point, i'll take what victories i can get

I'll keep you updated if you're interested, because i might have another question or two. Thanks!

once you start doing this for a while, you will learn that many times it's the simple things that can cause you BIG grief. double and triple check the return spring, then move on to the pedal itself, then the throttle linkage.

well, at the risk of deflating your elation (which i totally understand :)), that's not necessarily so. remember you will be spend a lot of time on the idle circuit and on the main circuit well below 7000, so those need to be right before you can claim success. once you sort out this open throttle issue and you can get it to idle, you will be much, much closer.

... and i am very interested. i will answer as many questions as i am capable and for whatever i can't answer (which is bound to happen at some point), i will try to get you in touch with someone that can.

i am very interested. i will answer as many questions as i am capable and for whatever i can't answer (which is bound to happen at some point), i will try to get you in touch with someone that can.[/QUOTE]

Thanks! So while sticking my head into the back of my beetle to get a better look at the carb, (working on this engine in this car really helps me with my space awareness) I noticed that the throttle lever on the carb was slightly pulled by the throttle cable. I took off the cable and, sure enough, that was what was behind my insanely high "idle". Without the throttle cable connected, the car idles well for not having a tuned carburetor, give or take some backfiring out of the exhaust, but I guess that's to be expected.

ANYWAY my big question right now is this: before I bought the car, it had been sitting for a year, unstarted. What is your opinion on the ATF trick? I read some places that it is good for cleaning out carbon and lubricating the apex seals, but then I also read that it eats away at the seals themselves and can ruin your engine... In my situation, what do you think of this trick?

my opinion is don't do it. i never really ascribed to using ATF inside a running engine, even when it was generally held in high favor. i do soak some parts in it though.

for apex seal lubrication, use your MOP, premix or both.

for carbon cleaning, the method i would love to try is steam (plain water), but given the space you have to work with in your Beetle, i don't know how easy it would be to perform it. the only other things i subscribe to (and actually do) are using some Seafoam or MMO in the fuel. i also put the seafoam directly into the chambers, too.

Thank you for the insight. I've read some things about guys saying that after they used ATF, it had eaten away at some seals and their engine started burning oil. You seem to know what youre talking about, so i'm going to trust your opinion on that! My dad has a few cans of seafoam, so I think ill funnel some in through the spark plug holes, turn her over by hand, and let it sit over night.

And in reference to that throttle cable, I'm going to check if it's kinked somewhere, but I'll probably need to take it out and regrease it..? Either way, its close to 90 degrees here in MD so that work is for another day

yeah, you can give it a good soak with the Seafoam over a night (or two) turning it periodically, then run it for a while - maybe add some more through a vacuum line as well.

i forgot to say congratulations! :) next up is tuning that Holley.