This post a followup to this thread I start a few months ago. You don't really need to click on it that. I'm starting a new thread since we're now dealing with a new carburetor and the video I posted previously is now basically irrelevant. I'm happy to report some progress finally, but some issues still need to be worked out.

Brief recap:

Had recently installed Super Six setup, new Weber carb, HEI ignition, new spark plugs, new cap/rotor/wires, new alternator - all stuff that need to be replaced anyway or could stand a proper upgrade. Car wouldn't run properly. Suggestions from board included vacuum leak, poor timing, bad carb, or a combination thereof. Went round and round with no good results. I've started a new job that I actually need to drive to, so a few weeks ago I threw in the towel and took it to a mechanic. Results: timing was off, carb appears to be bad. I think I was previously cycling the engine backwards while determining TDC because I've since screwed up the timing again but was able to relocate it on my own (and I seem to recall doing it differently last time). And the mechanic concurred that the carburetor appears to be bad because the mixture screw had to be turned all the way in to keep it running (when, according to him, it shouldn't have been running at all at that point) - plus the terrible rich fumes were still present. Also, I'd connected some of the components incorrectly. He said he did not detect any vacuum leaks. Perhaps the bad carburetor made this difficult though? He also did a compression test and all six cylinders read good.

So, I needed a new carb. I doubt I'm warrantied with the Weber since it's been almost two years since I bought it, and I just didn't feel like dealing with another one anyway (yes, this was a major blow to the pocketbook - I'm trying not to dwell on that fact). I got a new Holley 2280 and installed it. My Dart is running even better, and the rich fumes have mostly disappeared. So big points and much thanks to the board (particularly Reed and Dan) for trying to coach me through the last round.

So I shot a new video today. Before you view it, the present situation is this:

1. Per the suggestions of the previous thread, I've finally tracked down a timing mark and gotten a vacuum gauge. I could not find the bolt-on style timing tab of the later model engines online, but I finally found the only one they had at the junkyard in town with the most Mopars. I actually still had to tweak it a little as it was rubbing against the harmonic balancer when I first tried to install it - I thought that was strange as I don't think it was doing that with engine it came off of. Also, you'll notice in the video it sticks out over the outer most edge of the balancer, so I had to paint a white mark on the middle rung of my two-belt-groove balancer. As you'll see in the video, the vacuum pull is 16-17 inches.
2. I say the gasoline smelling fumes have "mostly" disappeared because there are still some present. I must be on the right distributor tooth, but the engine runs best when I advance timing all the way past the slot for the hold down bolt (even with the adjustment bolt on the underside maxed out to allow for the most advancement) to about 14 degrees BTDC.
3. I still can't seem to detect any vacuum leaks, even though it seems like the most likely culprit. I poured a steady stream of water around the intake mounts with no drop in RPMs, and sprayed carb cleaner around the base of the carb with no increase in RPMs. There are five vacuum connections on this carburetor. I have hooked up: vacuum advance, air cleaner assembly, and PCV lines. I have capped off: EGR and air canister lines. The PCV valve chirps and whistles at lower RPMs sometimes.
4. I pulled and plugged the vacuum advance line while I was checking timing, but there didn't seem to be any vacuum pull coming from that port when I checked it with my finger. This is odd, ¿que no?

That's everything I can think of. From what I've read, I should be shooting for about 5 degrees BTDC and about 20 inches of vacuum pull, and I'm falling short on both of those. Yes, the holes in my lean burn air cleaner are covered with packing tape until I can do a proper patch job. Here's today's video.

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J.R.
Tucson, AZ
'68 Dart 270 with a '76-'80 engine

Did the timing tab you installed come from a slant-6 engine? If so, what year vehicle was it in? And how did you put the engine on TDC so as to make your pulley mark at the "0" or "TDC" indicator on your newly installed timing tab?
What is your elevation above sea level? If you're at or near sea level, that's low. Have you checked the valve adjustment? How about timing chain slack, have you checked for that?
What makes you say so? The engine does not look or sound as though it has a vacuum leak, though I can't hear the tailpipe in your video.
No, it's normal to have no vacuum at that port at idle speed.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I would check the valve lash, it sounds a little on the loose side to me, but maybe thats just me....

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MRO....

Cheap, Fast, Reliable.... Pick 2...

Tucson elevation is 2650ASL.

The junkyards in town care less about slant parts and really don't know what they are looking for. Did you have the timing tab or cover pulled or do it your self. Just a month ago there where 7 cars with slants in them at the new u pull it. I didn't pay attention to the covers though.

That vacuum needle is definitely NOT steady. It is jumpy. The facts that the needle fluctuation is only over a 1 inch range and your valves are very noisy leads me to believe you would benefit greatly from a good lash adjustment. A good valve lash adjustment should quiet down the engine a lot, steady the vacuum reading, and probably improve your vacuum as well.

Dan is spot on RE: his questions about the timing tab and how you found TDC. There were several different timing tab arrangements over the years and you have to match the timing tab to the crankshaft dampener to get an accurate reading. Further, the outer ring of the vibration dampener can slip, leading to an inaccurate indication of TDC.

I suspect the lower than normal vacuum reading is due to misadjusted valves and timing, rather than a vacuum leak.

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Casually looking for a Clifford hyperpak intake for cheap.

Is this...? What forum is this?... Yes, of course.
I don't know what year vehicle it came off of. It was on a stand from a freshly pulled engine and I think he said he'd pulled it from his own van recently. It was the only engine I've seen online or in person with the bolt on tab so I jumped at it. I'll give the guy a call and see what he can tell me. I made the mark in line with notch on the outer edge of the damper.
Apparently I can skip Wikipedia. So what does that mean for the reading? I have not checked valve lash recently, or timing chain slack ever.
Well that's encouraging. I'll be sure to include it in the next one.
Oh. Well then why is it necessary to disconnect it when setting the timing?
I'll check that out if it comes to it. I got the tab from Arizona Auto Wrecking.
How would I check for that?

So a valve lash adjustment sounds like priority #1. I'm a little confused about where I'm headed next with the timing. I'll get back to you about the year of the tab. What am I looking for as far as timing chain slack, and how long can I expect that to take? The engine must have less than 20,000 miles on it since it was rebuilt (by a shop in '00ish). That's something that would have been addressed at that time, right?

I do appreciate your help once again, gentlemen. I couldn't do this without this board. One more question: I've seen in other threads that the dealer valve is the only way to go; would my NAPA PCV valve cause any problems related to this?

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J.R.
Tucson, AZ
'68 Dart 270 with a '76-'80 engine

Checking the timing mark is VERY easy. The only special tool you need is a TDC stop tool, such as the one sold HERE
Other people use a spark plug as the basis for a TDC tool. Get an old spark plug that fits in the hole and break out all the ceramic portion of the plug. Drill the center portion out so you have just a ring with threads on the outside. Now tap the inside of the ring to fit a bolt and you have made your own piston stop tool.

To check your timing mark, remove the #1 spark plug and thread the tool into the hole. By hand, rotate the motor counterclockwise until the motor won't turn anymore (the piston has come into contact with the bottom of the TDC tool). Using whiteout, mark the vibration dampener next to the 0 degree or TDC line on the timing tab. Now rotate the motor clockwise until the motor stops turning. Mark the vibration dampener again at the TDC mark on the timing tab.

Ideally, the two marks on the vibration dampener should be equidistant from the timing mark cast into the dampener. If the two marks are not equidistant, you need to measure the distance between the two, divide it by two, and make a new mark equally distanced from each whiteout mark which will be your new timing mark.

Alternatively, you can use the timing tab as a ruler and measure how far each whiteout mark is from the cast timing mark and then figure where the timing should be.

If you find your timing mark has slipped, replacing or rebuilding the vibration dampener should be moved to near the top of your automotive "to do" list.

Any decent machine shop would have replaced the timing chain during a rebuild. The easy way to check for timing chain stretch is to remove the distributor cap and rotate the engine over clockwise by hand until the timing mark lines up with the 0 mark on the timing tab. Now slowly rotate the crank counterclockwise (or anticlockwise, if you prefer) while watching the distributor rotor. Stop turning the crank as soon as the rotor begins to move. Now look where the timing mark is. If the timing mark has moved more than 5 crank degrees you should probably replace the timing chain.
Not necessarily if it is designed for your application. However, PCV valves can and do fail, and they are fairly cheap. It wouldn't hurt anything to be sure you got one that works and is designed for the year engine you are using with a two barrel carb.

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Casually looking for a Clifford hyperpak intake for cheap.

As Reed says, you need to make sure that indicated TDC is actual TDC.
Add 2.6" of vacuum to your indicated reading to arrive at what the reading would be at sea level (which is how it's usually discussed in books and articles). You lose 1" of vacuum for every 1,000 feet above sea level.
Get busy! Refer to valve adjustment and see here for the timing chain slack check.
Because depending on carburetor configuration, there might be vacuum there. It's easiest and most problemproof to specify that the hose be disconnected.
Yes, but the devil's in the details. Did they actually degree-in the camshaft (probably not) or just line up the dots (probably so)? The dots aren't always in the right place.
Probably not. Aftermarket valves can be unpleasantly noisy, but if they're correct for the application they usually work OK.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I'm sorry, Reed: I guess my question regarding dampener slippage was more a matter of how that happens and how to prevent it from happening again. Presumably, once one has verified slippage, the method you described is good only until the next time the engine needs to be timed, correct? I've been locating TDC using this method... sort of. I was just watching for the moment during #1's compression/combustion stroke that the bubbles stopped and the fluid just began to get sucked back in the tube - then marking the damper. Not very accurate???

Thanks SO much for answering my questions in detail. I will address these issues my next day off and report back.

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J.R.
Tucson, AZ
'68 Dart 270 with a '76-'80 engine

THe outer ring/belt groove member and the inner hub member are bonded to each other with rubber. When the rubber lets go its bond, the two members slip relative to each other.
Replace the damper.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Yup. What Dan said.

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Casually looking for a Clifford hyperpak intake for cheap.

The method you did to find TDC is fine. Its basically the same with a piston stop except that you dont have to turn the engine backwards for a whole revolution. I am sure you are with-in a half a degree or so....

_________________
MRO....

Cheap, Fast, Reliable.... Pick 2...

Oy, jeez, guys. I'm really need of some moral support here. I just took a break from my attempted valve lash adjustment. There's an oil-soaked towel in my engine bay and a rather large puddle underneath my car right now, and smoke from the burning runoff was getting to be too much. I tried going through all six exhaust rockers and then all six intake rockers and I'm not confident as to what I'm 'feeling' with my feeler gauges. I still hear some clicky-clacking, but I can't seem to pinpoint which ones it's coming from. And it's proving awfully hard to find that sweet spot between 'the gauge won't slide in at all' and 'this is definitely too loose,' which is less than 1/16 of a turn.

And worse news: I went back and forth cranking the engine by hand three times and discovered about 8-10 degrees of timing chain slack. What am I looking at for a timing chain replacement labor-wise?

I haven't gotten that piston stop tool but used my previous method to check how 'accurate' the mark on the damper already was. It lined up correctly with the timing mark off the the engine from the unknown year (I have yet to call him, but even if I discover my timing tab is from an incompatible engine, 8-10 degrees is still 8-10 degrees, right?). And I assume all this is meaningless considering the new realizations about the condition of my timing chain.

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J.R.
Tucson, AZ
'68 Dart 270 with a '76-'80 engine

So I don't know what went wrong with that valve lash adjustment, but I lost a lot of oil in the process. I just ended up having to shut off the engine and bumping it over repeatedly. I went up a size on the gauges to help ensure I wouldn't overtighten them. The engine definitely sounds better.

But again with the timing chain: considering that 8-10 degrees of slop, am I, without a doubt, looking at a timing chain replacement? And when it comes time to do that, Dan, you said something about "degreeing in" the camshaft instead of "just lining up the dots"; lining up the dots is the only method my manual mentions - what is involved with this? This job is going to mean replacing the chain, oil seal, and cover gasket - anything else I will need to or should replace while I'm at it? Any other big surprises I should expect? And the damper pulling tool, is it just a universal tool, or will I need a special one?

This can of worms just keeps getting wormier. Much thanks.

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J.R.
Tucson, AZ
'68 Dart 270 with a '76-'80 engine

Sorry to keep bumping my own post, but the flow of information (which was really helping) seems to have halted. Maybe because of Christmas fast approaching. Or maybe because I'm a hopeless case...

Backing it up for a minute here: Dan, in your 11/13/12 post in this thread you said
Were you implying that their failure to do this would have caused a new timing chain to wear prematurely? I've read this thread and this thread, and I just need to clarify - do I need to remove the head to do this job properly.

I'm getting ready to pull the trigger on ordering a new timing chain but want to make sure I know what I'm in for.

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J.R.
Tucson, AZ
'68 Dart 270 with a '76-'80 engine