I'm still betting on a vacuum leak. Some mismatch between the manifold, spacer, carb or gaskets. Spraying is the best way to tell, a vacuum gauge is of little help and listening through a hose is iffy at best..

 

A vac gauge is useful because it determines a baseline for a metric crapload of possible issues, especially when trying to diagnose remotely over the internet.

If we can figure out what the problem ain't, that helps. Any tool is only as good as the person using it. I don't try to memorize all the functions but there are probably a dozen or so. Anybody who says they don't work to indicate a vacuum leak is smoking their socks, RTFM!

 

Still keep coming back to this, it's not (technically) idling fine, it won't at idle at all if you stop and think about it.

Y blocks like a lot of initial advance, way more than 6 degrees factory setting. I run 14 BTDC or thereabouts and it pulls 18 in Hg, @ 500 RPM. Sure you're not running a pre 57 dizzy load-o-matic or something? The numbers you're getting don't make sense.

 

He said it has 16 at lowest idle and 18-20 at a little higher. What does that tell you for your internet diagnosis???????

 

While the factory setting of 6 degrees may not be the ideal setting for a Y it should idle fine and not die when the choke plate is open....

 

Did you check the float level in the carb? If you did a acid or high-alkalinity soak on the carb pull the float bowl and make sure plastic parts did not melt the do a float bowl level adjustment while engine is running. if it was a large leak in the vacuum system the advance in the distributer would not work when you advance the carb while engine is running also engine probably would not start. I would start on the carb and go from there. If it is a stock carb and you can not get to all the insides and no float bole adjustment time for a new carb. hope this helps

 

Well I am used to using a vacuum gauge on an engine that will idle without using full choke. I'm not certain that those are valid engine vacuum indications in the first place. I don't think a Y will pull 20 at 6 deg. BTDC @ 500

 

That's why I made the comment about running the valves as the wider the lash the lower the vac and as noisy as your valve train is this is where I would look.
I found this on another site,
Valve timing too, affects vacuum gauge readings. Valve timing can be late because of improper installation of timing gears, but more common than this, tappets are set too loose, causing the valves to open late (and close too early). This condition would reduce power considerably. Consequently, the speed of the pistons would be slowed and this would be still another reason why the vacuum gauge reading would be low.


although, if you are running the engine with the choke, you either have a fuel starvation problem or a Vacuum leak.

 

True, and for better pinpointing I use the red straw.
As for listening through a vacuum hose, if this isn't working for you, you are probably doing it wrong. I have pinpointed many leaks that spraying anything only found the general vicinity of. Using both is good.

 

Iwlbcnu; Did you solve the problems with your engine?

 

No, irritated, lost interest and gave up for now. Going to rebuild another 2100 and try when I get time.

 

I can understand the frustration. I like your idea of rebuilding another carb. Rebuild kits are cheep enough, and if noting else you will have a spare. It seams to come back to the carb. with no manifold vacuum leak and no valve timing issues.
Did you try adjusting the timing using a vacuum gauge?
This quest of your's, has my interest. Let us know how it turns out .

 

Taking a break from a problem is a GREAT plan! Some of my best problem solving happens when I return to the "problem" fresh. Keep us updated and I 2X agree on the second carb

 

I'm not a paid mech, but I have a lot of motorized hobbies so not a newbie, and this has driven me nuts. I am big into early Broncos, so have a few 2100's laying around to try. The one on the truck was replaced at some point by a reman 1964 version. The sticker washed off in the carb soak.
Right now it runs, and I can drive it around the farm, so working on the brakes. The timing is way advanced, the idle adjusted to where it will idle once warn, but you can tell it is rough, and smooths out by closing the choke plate. Still sounds leak to me, gonna break down and spray the intake this weekend. The carb spacer gaskets both have nice imprints showing they are sealing. Also gonna run the valves hot to verify lash. I've got some other hobby stuff to do, so not sure how much time I will devote to this. May go up for sale.

 

Well I'll be!!! Pulled out several carbs and one had the same style Venturi, so I just swapped it and it purrs like a kitten. No clue what's up with the original, I ran a wire and blew all thru it again. I've got it soaking again as I found nothing wrong with it.
Thanks for letting me vent