VW - Air cooled engine help
 

My brother just bought a rebuilt VW engine for his bug. The guy rebuilt it about 3 years ago, dyno'd it and then it sat in his basement. Apparently it was a very well done rebuild, although I admit I couldn't tell the difference between good and bad.

The engine is in, and it starts. It's runing rough, and if I remove either the #4 or #3 plug wire, it makes no difference. (Firing order is 1-4-3-2). If I remove #1 or #2 plug wire, the engine stumbles and just about dies. It's getting fuel and spark to all cylinders. The exhaust pipes on #3 and #4 don't get very hot though, so it seems it's not firing well. Plug wires are on correctly.
Another thing that may be a clue as to what's wrong: the tach is reading very high, and is kind of erractic.

Is this a timing issue? Any help is much appreciated?

I'm not much of a technician, but what the hell...

Pulling two plug wires and having no difference implies they're not contributing much. If what you said it true of the rebuild and it used to run good, I get the impression there's maybe stuck rings or maybe stuck valves.

I'd suggest a compression test. If you have a low cylinder(s), put in a little oil into the cylinder and see if it comes up. If it does, maybe mix a little transmission fluid into the oil to unstick the rings?

Otherwise, if you have low compression and oil doesn't help, check the valve adjustment?

I dunno about the tach. My guess is it's unrelated.

Thanks Steve.
Before we started it up, we squirted some oil in the spark plugs holes and let it sit overnight. The next day we cranked it over by hand a few times to make sure everything was moving freely with no funny noises.
We got it started Sunday afternoon and it ran rough. Then let it sit last night and I adjusted the valves today to make sure they weren't out of spec. All were very close, and at the most some were only .001 off.
I'm assuming the problem has something to do with sitting for a few years.
I guess next up is a compression check. My brother is checking on some VW forums tonight to see if he can get any information as to what the problem might be.

Your valve clearances suggest they're okay. I'll bet your rings are stuck, but can be broken free. Do the compression test.

If they're low, Swepco 501 is killer stuff. But it might be hard to find.

Are there fresh plugs in it?

I'm not sure about the plugs. I assumed he got new plugs, but they may old.

So if the compression is low in those cylinders, what do I need to try to free up the rings?

Thanks for your help.

Also, get John Muir's "Idiots Guide" to vws... and keeping them alive forever.

(even as a mechanical id10t myself, i use it as a how-to and what-to for my 356, and Elfrinks, et al. for specs and measurements, etc)

Well, I think others will have better knowledge than I, but I've heard automatic transmission is good. Don't know the correct ratio, guessing 20%. That Swepco 501 is excellent if you can find it. Comes in pint bottles.

The cavalry should be coming soon...

I don't know about "cavalry," but I can offer some insight for a decent forum. My VW friends hang out at shoptalkforums.com and thesamba.com.

Good luck -- sounds like a fun hobby car. :)

Dan

being that the valves seems ok ( that was my first suggestion). valve adjustment is always a big problem on those motors, id go over the ignition system. check the points( if it still has them). also change the condenser.

rings and valves don't explain the Tach doing funny things. I'd check points and condensor and all the distributor and coil connections, and be sure to check the grounding of the point breaker plate.

What type of distributor are you using on this beast? I've seen some strange quircks with the porsche type 009 centrifugal advance model. Do you own a timing light?

Tshabet - the 009 is *not* Porsche type. Only VW distributer that works "properly" in 356/912 engines is the 050 since it has nearly the same curve and max advance as OE distributers.

(yes 009 can be made to work, just has too much static advance if you want to have 32-35deg at 3000+ rpms)

id10t,
Sorry, I didn't mean to imply that the 009 was the porsche distributor used in that era of Porsche engine, my reference to the 009 as "porsche type" is based on what VW buffs/parts catalogs call them as a replacement unit to differentiate them from the vacuum advance distributors that came OEM on VW bugs. I believe the term "porsche type" may have originated with Muir, the author of the "how to keep your volkswagen alive" books. From page 90 of Muir's book:

"Just what kind of distributor do you have? Volkswagen has used three main types through the years: mechanical (centrifugal) advance, semi-mechanical advance and vacuum advance. The first two types have been the same all the way, but the vacuum advance distributor has gone through several modifications and has been standard equipment on all models for many years. I hate them! They are another sop to American buyers who refuse to learn to shift a car with a little coordination. This is just a personal beef, so forgive me. I use a straight mechanical advance distributor, called the Porsche Type, which advances the distributor on rpm as the engine speeds up. Most VW race cars and beach buggies use the same. It gives a very good power curve on the VW engine."

The 009 was a bus dizzy. I would check the compression first. If it reads low, remove the rocker assembly ( 2 nuts..just like you) and smack the valve stems with a rubber mallet to crack them and snap them back into shape. if you still have no compression then look at the rings being stuck. I would think valves first. If it's just a spark problem replace the whole mess. cap, rotor, cond., and wires it's all pretty cheap stuff. do all that, take two asprin and type to us in the morning. yes John's book is the best. but I believe out of print. Does this car have the stock Solex carb or what?

The book is still in print, you can buy it on Amazon. Muir passed away a while ago, however.

yes I knew he died. didn't think the book was still available. ...I have a first edition. john was quite the card.

Definitely a card....I have an early edition (wire-bound) that my dad bought after returning from Germany with a 1969 standard beetle, and also a more recent edition which I bought new when I restored my first VW, around 1994. The most notable difference in the later edition is a chapter on body repair/restoration (rust never sleeps!) and a guest authored section about hotrodding VW engines. Still a major reference for me when working on any carbureted engine...had it out last weekend while I was trying to get spark on a 1938 buick "dynaflash" straight eight.

Mine is a wire bound edition as well. I loved Johns humor. He also did a Rabbit book, it's pretty funny as well. You dad brought it back in 69!!! Man I'm feelin' old now.

Wow, thanks for all the responses.

Honestly, I don't know much about the engine. I know it's a performance build and it's anything but stock. It has Dellorto carbs and is in the 1900cc range. I'm pretty sure my brother has some info on what exactly is in the car. We won't be able to get back into it until the weekend anyway.

I'm pretty sure it's a ignition problem. He's getting replacement cap/rotor/points/condensor. They are all new, but the engine has been sitting for a few years in a basement. We'll see what that does since it's cheap stuff. I'll also check the compression.

Thanks for the help. Hopefully I'll report back good news.

Great book. This was one of those things that was handed down to me, i have since handed it down too. I just recently bouight a new copy at Borders.