I'd like to check my valve timing to verify that the new timing chain & crank/cam gears are installed properly aligned.

What is the intake open & close points for #1?

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1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/

What cam do you have?
DD

Cam & engine are stock for 1965.

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1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/

The factory cam should have 16 degrees of overlap.
You will want to check the overlap event at TDC(Exhaust) to see if the overlap is centered over TDC.
Ideal would be to see the intake opening at 10 degrees BTDC and the exhaust valve closing 6 degrees ATDC.
DD

Thank you for the prompt reply.

Using a dial indicator off the valve spring retainer I found the intake & exhaust to open and close equally on both sides of TDC.

The overlap comes out to 30 degrees with the intake opening 15 btdc and the exhaust closing 15 atdc. I tried measuring each valve 4 times before stopping for the night.

FYI I previously checked the piston against the balancer mark and found a 3 deg difference & remarked the balancer.

Is there a tolerance on the cam that could make a factory cam acceptable with an overlap variation from specs(30 vs 16)? Would a greater overlap effect intake vacuum at an idle? My current fast rough idle has a intake vacuum swinging from 16 to 13 in wg.

With the opening and closing equal on both sides of TDC, can I assume that this verifies the cam is properly aligned with the crank?

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1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/

Yes, it sounds like the cam is installed correctly.
Here is a chart of Factory Cam Specs

It sounds like a different cam got into your engine sometime in the past.
Have you rechecked your valve lash adjustment? I would try a looser setting. That would bring-up the manifold vacuum and smooth-out the idle.

DD

I readjusted/opened hot valve clearances- Int .012 & Exh .022 just to be sure. Valve overlap change was minor( 30 to 28 ). No impact on surging.

FYI the intake vacuum is 21 in wg for the first 20 sec of smooth running (whether started hot or cold). At that point missing & surging begins with vaccum swings from 13 to 16.

The new (not rebuilt) 1920 Holley has fresh float needle & has been adjusted dry & checked wet to factory settings of 27/32 in. Main jet is #56. Fresh accel. pump diaphram produces generous discharge & engine revs without hestitation. New fuel pump hasn't been checked for volume yet(on the list). The new fuel filter is a 1 inch dia steel filter used on 70's 302 Ford trucks (so that the 1 inch radiant heat protector can be installed over it). (Measuring the fuel pressure after the filter is next on the list)

All new ignition components include conversion to new Mopar electronic ignition with matched new ballast. Old radio interference capacitor has been disconnected from the new NAPA coil since the capacitor is the only "OLD" component. New Mopar distributor should have a steady rotor since I installed the Guru timing cover cam stop. It's set initially at 7 btdc (with dist vacuum hose disconnected) and shows a total advance of 13 deg at the jumpy 500 to 700 rpm & swinging 16 to 13 in wg vaccum. It's firing the NGK ZFR5N extended reach plugs.

Heat riser is open in hot position

All new vaccum/pcv lines have been disconnected & plugged (one at a time) looking for a vaccum leak. The Guru instructions were followed for installation of the stock 65 exh/int manifolds (no egr) using the generous Australian Graphite gasket & Hylomar blue goop on the intake surfaces.

Valve grind is fresh with hardened seats installed in the 65 drool tube head. Fresh rings & bearings were installed at the same time while cleaning inside of the oil pan with engine in the car. (Compression check is on the list but it should be excellent since the bores only showed a .001 taper).

What could be added to my list to check for a condition that allows smooth idle for 20 sec and then go irratic with a 5 in wg vaccum loss & swings?? Electrical component break down under applied load/heat?? Fuel can't keep up with demand??

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1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/

You haven't got a fuel supply problem. Those show up under high-speed/high-load conditions, not at idle and low speed. You can save the fuel pump volume and post-filter pressure tests for after this current problem is fixed.

I would say your problem is likely carburetor- or ignition-related. You mention a "new Mopar distributor". Which one? A passenger car type, or the Mopar Performance item that used to ship with the MP electronic ignition retrofit kits. Also bear in mind the Mopar-sourced ignition control units have been of poor quality for some years now.

There's something the matter with your carb and/or distributor calibration if you're seeing six degrees of vacuum advance added in at a low idle of 500 to 700 rpm. You should not have any significant vacuum advance at idle. I'm curious what happens to your idle quality if you disconnect and plug the vacuum hose leading to the distributor vacuum advance. I'm also curious how jumpy or steady the timing looks under a timing light when it's idling poorly.

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

Slowly close the choke flap to see if you can get the idle to smooth-out.
Sounds like a lean idle condition.
Also plug the PCV valve and see if that changes the idle quality.
DD

The "New" Mopar Distributor has a tag with top line 28 6 btm line 3874714.

The engine starts with just a click of the ignition switch (no cranking) and runs smoothly with high intake vacuum (21) for 20 seconds consequently the ignition module is OK for that period of time. This occurs whether the engine is started cold or started hot.

The PCV valve & distributor vacuum were disconnected/plugged and the idle quality remained poor. I checked the timing with the lines plugged and it was steady while the idle was poor (intake vaccum swinging from 13 to 16, rpm swings 200-300 rpm).

Lifting off the air cleaner cover to try to close the choke flap resulted in a stall. This repeated multiple times. Instead, I used the choke link to close the choke and the engine smoothed out considerably. Vaccum also rose to 21. RPM surged to a steady estimated 800 or more. This test repeatedly came up with the same result. I did this when the engine was hot & at temp. This would suggest fuel supply is not a problem effecting idle? Does that logic apply to the float as well?

Does this point to the idle system or main metering system? Because the carb is (as new)clean , inside & out, am I looking for a port not drilled correctly or wrong/failed gasket, or ?

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1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/

The next test is to look into the top of the carb and find the idle air bleed holes, these are small brass inserts, presses into the carb body, just above the venturi.

While the engine is running, use a long pencel eraser and plug the larger hole.
DD

OK, that's a fine one. But you still shouldn't have vacuum advance at idle.
Well, let's not make any assumptions yet...whatever is causing the problem doesn't cause the problem for 20 seconds after a startup.
OK, that's a good piece of information.
OK, this points very strongly in the direction of a lean-idle problem as Doc said. At the risk of asking a basic question, have you tried simply readjusting the idle mixture? Assuming you have, then grab a spray can of carburetor cleaner (I like Berryman's B12 Chemtool best), turn-in the idle speed screw to hold the engine at a fast idle of around 1500-2000 rpm, and flush out the air bleeds. When you look down the carb throat, you'll see two holes facing the sky at the front. One is a tiny pinhole, and the other is larger, about the size of the red straw on your can of carb cleaner. With the engine running fast, press the spray straw against the pinhole and give a blast or two of cleaner. Then put the spray straw in the other (larger) hole and do the same. Then remove the idle mixture screw completely and spray a good shot of cleaner into its hole. Reinstall the mixture screw, seat it lightly(!) and back it out 3 turns, then lower the engine idle speed to 650 rpm and adjust the mixture per this procedure.
The carb base gasket needs to be installed right way up and right way round, or you will have problems. They are stamped "TOP FRONT"...did you carefully make sure to install it correctly?

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

The carb base gasket has the top & front correctly located...I verified this by pulling the carb. While I was at it I installed an old carb to verify it's a lean carb & to investigate the high advance. My first step several day ago was to try different idle screw setting. Nothing seemed to change although it was hard to tell with the roughness.

The old carb installation allowed the slant to run fine at an idle and turn down the rpm to a normal idle. The advance dropped to 3 deg difference between having the distributor vacuum line hooked up and not hooked up. Rpm varied slightly also.

I'll bench clean the air bleeds first before reinstalling the new carb & trying another cleaning

Thank you for helping narrow down the problem.
Once the new carb is performing reasonably we'll come back to measuring the vacuum & mech advance for the distributor.

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1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/

Blast Chemical Cleaning of Air Bleeds cleared up the rough idle and allowed a decent look at the advance without & with the distributor vacuum line hooked up at idle (advance changed from 4 deg to 7 deg). Timing & intake vacuum (20.5) were steady too at idle.

There is a angled hole thru the carb body(carb # 2887-6), just above the carb bolting flange, allowing outside air above the throttle plate. It's located on the driver's side positioned below the choke pull back diaphram area. What is it's purpose? I have two other carbs (the original R3058A and a 70's) which do not have this hole.

Thanks for the help.

Based on the way it's starting and running, it should pass the next tests on the Sun testor, etc. I'll put a curve together for mechanical & vaccum. Where can I look up the specs for the electronic distributor 3874714 conversion?

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1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/

Great! That sounds like progress.
Get a 3/32" hex key ("Allen wrench"), insert it into the hose nipple on the vacuum advance, and turn it one full turn clockwise. This should eliminate the vacuum advance at idle, which'll make it a great deal easier to attain a steady and consistent idle (and improve off-idle driveability, too). The one-turn suggestion is just a starting point; use your timing light to verify that there's no longer vacuum advance being applied at idle. With that distributor, an initial timing setting of 6 to 8 degrees BTDC (vacuum advance hose disconnected and plugged, engine idling at 650 rpm or so) should be close to optimal.
Good vacuum reading. So the poor-idle problem is all the way solved, then, it sounds like?
It's a secret passageway to China. Actually, it's to smooth the power valve and vacuum advance transitions. Some carbs have this hole, and others don't.
In a '76 FSM.

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