While everyone else is helping with your genset problems, I've been thinking about your vacuum hoses and engine performance issues.
eyeteeth wrote:
Griff - I've found a couple diagrams, I think the one that is messed up controls the Idle/timing advancement, its rough when cold, but smooths out once it warms up. I haven't driven it anywhere, but before rebuilding the carb it was starting to smoke a bit... and that's gone now. I found a factory guide on the carb... but the whole thing to tuning it is measuring and bending... not much screw turning... maybe I'll take it back off this winter and play with it for a week... we'll see.
It sounds like you have two effectively separate issues. Individually, either will affect engine performance. Combined, it's a case of the "the sum being greater than the parts." (At a minimum, the two could be causing mistaken impressions regarding what going wrong.)
These are (1) vacuum line issues causing timing issues and (2) carburetor choke issues creating starting/warm-up issues.
Both of these are issues that diminish once the engine warms up but do not necessarily go away entirely.
I've often quoted an old boy who taught me, "Ignition first, fuel second." So, I'll start with a possible ignition problem caused by a faulty vacuum system.
A thirteen days ago, I posted a link to an article that discusses distributor/ignition timing in depth. I recommend reading the article for more information. (Page 708 in this thread.)
The red arrow in the following picture points to where a small diameter rubber vacuum hose should be attached. (The vacuum port in the picture is capped with a rubber cap ... remove this before trying to attach the vacuum hose ... and save the cap, having extras laying around comes in handy.)
The silver thing near the arrow is the vacuum advance control, which operates somewhat like an electromagnetic solenoid. Vacuum caused the control to pull in a spring-loaded plunger, which advances the distributor (i.e., engine/spark plug) timing. Decreases in vacuum partly or completely releases the plunger, causing the timing to be ******** (opposite of advanced ... the unmentionable nanny routines got me again.)
Engine vacuum is greatest at idle and decreases as the engine picks up speed. The vacuum-driven windshield wipers on my '47 Willys Overland wagon taught this to me well. At idle, the wipers went like crazy, dancing and running like a thief with a shotgun-load of rock salt in his butt. In-town driving slowed the wipers considerably. At highway speeds, the wiper could barely overcome the wind hitting the windshield, taking a second or more to complete a swipe.
The reason for using engine vacuum to control the distributor's timing is simple. At idle -- when vacuum is highest -- the engine needs more time to complete combustion. The converse is true at higher RPMs, when engine vacuum is less. So, engine vacuum is a handy means of reacting to this variable.
Here's a good and more complete explanation of this.Yes, this technology is ancient, dating back well over 70 years. However, it works, is simple, and remarkable effective.
Over two decades ago, at a software conference, I talked with someone who wrote the software code for engine computers. She told me attempts had been made to eliminate vacuum advance and move the function into the computer. She said the result was invariably large amounts of complex code, with tests indicating it was less effective than "the way it's always been done." (I've seen indications people have managed to do so since then but most engines still use vacuum advance.)
Normal process for timing an engine involves disconnecting and plugging the vacuum advance hose. This keeps the vacuum advance from messing with the timing process. (Plugging the hose prevents a vacuum leak for affecting engine performance during the process.)
Sometimes, the mechanic forgets to reconnect the vacuum advance hose. (I wish I had a dollar for each time I've solved someone's problems by simply reconnecting the hose.) An old, leaky vacuum hose -- or a serious vacuum leak elsewhere -- can also adversely affect engine performance.
BTW, inadequate vacuum advance means wasted gas due to incomplete combustion.
Vacuum advance is most important at idle, so a rough idle often indicates a leaky vacuum system. I don't like chasing problems so I have a tendency to replace vacuum hoses just to be sure, especially when rehabilitating vehicles more than 20 years old. (Plastic doesn't work well for vacuum hoses and rubber tends to deteriorate with age ... especially when routinely subjected to extreme temperatures.)
Your positive crankcase ventilation (PCV) system is another, apparently unrelated, source of ignition timing problems. The PCV system uses engine vacuum and the relatively large hose has the potential for a significant vacuum leak. (A stuck PCV valve can also create problems but hose issues are more frequent.)
The way the PCV system works is the reverse of the distributor vacuum advance. At idle, PCV is relatively unimportant and becomes critical at higher engine RPMs. PCV valves close in response to significant engine vacuum and open when vacuum decreases. So, a PCV valve that's struck open will rob the distributor of vacuum advance when it needs it most.
Before closing, I should mention you're lucky chasing vacuum problems on a Dodge. In the late '70s and early '80s, Ford created incredibly complex vacuum systems in an effort to meet EPA standards. (This is why some people say Ford engines suck.) When I first saw the vacuum system for my '80 Ford Bronco, I immediately thought Rube Goldberg. This is unfair, as Rube Goldberg machines pale in comparison to what Ford created.
