Callin the Cap'n or other engine Yodas, Manifold vacuum gauge readings Options

[ThePaintedMan]

I took the advice of a few folks on here and finally got around to buying a quality vacuum gauge. As a primer, I've had all kinds of issues, from carb synching, timing, etc. But I think I've finally got it running fairly well. The car is a '73 with a 1.7, dual Weber 40 IDFs.

Anyhow, I did a compression test the *right* way this time with the throttle open and after the engine was warm and got 110 across the board. Not great, but not awful. Next I moved onto checking the vacuum on each manifold port at the base of the carbs. I get wildly, but consistently fluctuating numbers on each cylinder. By that I mean, at idle, each cylinder displays the same thing - the needle bounces from 5-17 mm Hg instead of a steady number. I've been reading up on this at:

http://www.thesamba.com/vw/forum/viewtopic.php?t=476817

and the great animations at:

http://www.therangerstation.com/Magazine/S...VacuumLeaks.htm

Is it then possible that I have FOUR burned exhaust valves? I had been suspecting I had at least one for awhile, due to seemingly high CHTs on #3, "sucking" coming from the tailpipe and the fact that #3 doesn't suck nearly as much air from the velocity stack as the others. But now I'm suspecting a larger issue. Is it possible that both heads are loose? I see some oil leaking from the cylinder-case junction, but don't see anything from the head-cylinder junction. Would it be worth taking the in off and trying to retorque all the head studs, if nothing else, for piece of mind?

-George

[ThePaintedMan]

I feel like all of my posts end up being "doomsday scenarios," lol. Or that I keep putting too much information in a post at once. Once I went back and read it I'm sure it was confusing for you guys. Very sorry, but always grateful for your help!

As far as your responses, yes, I used a "snail" gauge to sync the carbs. I think the throttle shaft on the drivers side carb is a little bent since when the other passenger carb is completely at idle-rest, I can still pull on the driver arm and get it to idle down some more. For the meantime, I have been synching them at higher RPMs since this is where most of the driving is done anyway.

Regarding the bouncing signal, that makes a lot of sense. I should have known the instructions I was going by were not based off of a single-throttle-body application. My mistake.

This still doesn't quite explain why cylinder #3 doesn't draw the same numbers as the rest of them, though. I'm curious what that might be about. I read another post awhile back with someone having a similar issue, but never heard any real ideas on it, other than maybe retorquing the heads.

It is very possible that this engine has a carb cam in it, but I have no way to verify it. I got no information on whether it was rebuilt by the previous owner(s), but I was under the impression it was original. Its obviously lived a hard life, but its taught me a lot and got my ass to and from work all summer. I have been speaking with Jon (no1uno) over in Orlando about a rebuilt 1.8 he has to swap out eventually. I'm just not quite ready to give up on this one yet (IMG:style_emoticons/default/smile.gif)

Thanks for your help and continued tutelage! (IMG:style_emoticons/default/beerchug.gif)