I see. Experience with this anyone? How is the head cross over port shaped/constructed? Is it just a channel through the head? Then it won't lead much heat up to the manifold but maybe enough to cut the warm-up time some?

Yes, the crossover is a rectangle shape at the intake manifold edge of the heads (below that curved hollow at the center of the head) and intake, but changes shape as it passes through the head to the exhaust ports, and also changes shape as it passes through the intake manifold itself.

When the weighted and spring loaded flapper valve (heat riser valve) on one exhaust manifold (I believe its the right manifold, its been a few years) closes, it sends the exhaust back through the port on the head, under the pendulum on the intake, through the port on other head, and into the exhaust. If the flapper valve doesn't close, or isn't there, the exhaust heat drifts up (heat rises) to the intake. Over time (generally 8-10 years), the carbon from the exhaust plugs up the ports under the intake and at the intake manifold end of the heads. That carbon needs to be dug (chiseled) out of the ports.

As long as the ports are clean, there should be enough heat passing into the intake to help the cold running condition for several years. Gene

Good reading Poorboy. How does the exhaust enter the crossover - I know where it comes out of the head an into the intake but how is it routed from the combustion chamber and into this channel? Part of the reason why I ask this is that I know my crossover ports are carbon plugged and need to be cleaned out. Never bothered to do this as this function not was going to be used.

Op has stated that his installed valley cover pan has the close the cross over option. It was suggested very early on in this thread that his intake may not have this port,,,,blocking with the valley pan will give indentical results,,,,a cold or very slow to warm up intake.

Again I repeat, this is not recommended for a normal street driven engine. The lack of early and adequate heat to his intake manifold as oft repeated in this thread is a leading candidate for the erratic running issues that he had described.

The factory installed these ports for a good reason. Not anticipating they might be disabled by some tuner with a better idea.

Now we know my intake has crossover port and it should be used. I will do that but have to open up the carboned up ports in the heads and fiddle with the valley pan. Can the head ports be all cleaned up from the intake side? I still want to know how the exhaust gasses is routed from the combustion chamber to the outlet port on the heads.

The center port in the head ties into the exhaust port, the flapper in the manifold routes exhaust from that side, thru the intake to the other side till it warms up and the flapper opens. With headers the flapper is moot since headers do not generally have them.

A vacuum and a screwdriver is all you need to clean those ports out.

I, personally, have never seen it plug up and I've been fooling with Mopars for 30+ years. Some say it happens, I wonder why?

Great, Supercuda! My 440 came out of a '67 Chrysler 300 cab and the crossover ports is completely glogged with carbon deposits. So is there a passage from one or all exhaust runners to the crossover port in the heads?

In the head, just one port if I recall correctly, I haven't played with a big block in 20 years. However, in the stock application the passenger side manifold, with the flapper in the outlet port directs all 4 cylinders exhaust thru the intake.

I can't find a good drawing of how it works.

what about all the aftermarket heads that have no crossover?
my 526 has RPM heads, and a holley 1000cfm hp carb, with no choke housing. no issues with cold start/warm up.

Do you live in Norway?

Your distributor is hooked up to manifold vacuum, and not ported, correct?

What is your vacuum in drive?

At what vacuum does the vacuum advance start advancing?

If vacuum in drive is below where the vac advance engages, you will have issues, particularly when cold. If that's the case, you'll need to use a hex key in the nipple of the vacuum can to lower the point that it engages, to prevent that overlap.

Easiest way to test this is with a mity-vac and timing light, or just take the distributor cap off and watch for it to move.

Yes what about that?

Supercuda: Norway yes!

Hoozie: Running manifold vacuum - not ported. No vacuum reading in drive as it is a manual. Idles at 12hg vacuum. Not sure at which vacuum the advance kicks in but should be well under 12 hg as it is all in at idle.

Edelbrock carbs and open/single plane Torker-intakes don't always like to play well together.

Try installing a 1", or better, a 2" spacer under the carb and see how the engine likes that. (But make sure the spacer has 4 holes, not the 'open' type.)

The spacer mostlikely will improve the engine's vacuum-'signal' to the carb and it in turn, will react much better and quicker to changes in the throttle.

General 68:
If you are running the FBO manifold distributor like I do, I know mine specifies a minimum of 12" vacuum per Don. I tested mine and my timing at idle stays solid down to 11.5", then below that the timing drops off. You might be right on the edge unless Don did something different with your setup.

Ok, running manifold vacuum is one of the problems.

As you open the throttle manifold vacuum drops and timing backs off causing a similar problem to what you are seeing.

As a test run ported and see if that helps.

Yep, that low of vacuum at idle is most likely the problem. Mine idles at 17", and sits at 14" in drive. Vac advance doesn't drop out until 10".

Like supercuda says, I bet you're right on the edge of advance. As soon as you put some load on it, the advance goes away and your idle drops. This would be exacerbated when it's cold.

Might be on to something here guys. I'll start with plugging the vacuum advance for a test, keep the static 20 degree advance, reset the idle micture and go from there.

BINGO! (I think). Plugged the vacuum advance and it acted better on the choke. No sure how well it drives after that as it was still touchy during warm up but needed more trottle opening from the idle screw (ofcourse, after losing 8 degrees vacuum advance) and readjusting the idle mixture. Runs super when warm. Had already put back the bigger jets. Needs some more testing but all in all it is a lot better.
I was debating the manifold vacuum with Don a couple of years ago but didn't get any love.
Can't wait to see how it drives at next cold start! Thanks a bunch all!!

Once it's running well, you'll want to add the vac advance back to the ported side so during cruise you still have the additional timing and cleaner burn.

Yes vacuum advance will be hooked up after some more testing.