The counterweighted spring on the exhaust manifold, does this hold that door open or closed? The spring on mine is very tight, and I live in an area that is VERY hot in the summer, and doesn't get too cold in the winter (rarely below 40 F). I have the choice of having the spring very tight, or very loose. Which is better for my climate? When the door is closed, does that make the intake manifold hotter?

One reason I ask, my car has been pinging above 3000 rpm when the initial timing was set at 10-12 degree advance. I tried backing off the timing to about 4 advance. It still pings, but mostly after the car is good and warm. Would overly hot gas burn wrong? I'm grasping at straws here. Besides, backing off the advance seems to have robbed a little low end power (or is this my imagination).

1. When the door is closed, the manifold under the carb is cooler.
2. Engine temperature will affect ping. The engine is more likely to ping the hotter it is. Where's the temp gauge when it pings?
3. Backing off the timing will decrease power.

4. Have you tried premium?

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

When is the door closed? Does the spring hold the door open or closed? I want it open, do I reduce or increase the spring tension?

The engine is running right about 190-195 when the its over 100 here, when it is cooler outside, is running around 180-190. I was just thinking that if the door is always closed, and it is over 100 outside, the intake manifold would be getting WAY hot.

I currently use premium, the the engine is 9:1 compression, cammed, bored.

I might as well increase the timing. I ordered a Mr. Gasket MOPAR recurve kit. I'm sure you will see some future posts as I try to figure that out. Thanks!

A cold spring opens the door. As the spring warms up, it closes the door. (or it might be more accurate to say that the spring loosens up and allows the weight to close the door)

You want the door to be closed, not open when it's hot. (closed is counterclockwise)


Since you changed the cam and compression ratio, I'd say that the advance curve does not match what the engine wants......


Someone here might have similiar engine specs and tell you what advance curve you need (or at least get closer)

_________________
Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

What kind of governor does that distributor have in it? If it has a 15r change it and get a 10r. Then go from there with your recurve.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

How do you determine the govenor?

These are governors, the one with the long slots is a 15r and the one with the short slots is a 10r.


and here is a governor installed. The i.d. number can be seen clearly stamped on top of it. As you can see this is a 11.5 governor.




They will usually have a number stamped on the top or bottom of them, like 15r, 11r,10r and so on. 15rs had long slots so they could overadvance the engine easily if used with springs too light. Emsvitil knows alot about this subject. He did a very extensive article on distributor recurving. Dusteridiot knows alot about this subject also.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

Thanks!

Where is this article? I don't see it listed.

Thanks

Not so much an article, but actually just a very, very detailed thread:

http://www.slantsix.org/forum/viewtopic.php?t=13264

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Used to own:
'82 Dodge D150
Erson 270 Cam, O/S valves, mild port work, ~9.5:1 compression

Currently fighting with an '85 VW Cabriolet

My other passion

That "door" in the exhaust manifold is neither open nor closed. It deflects exhaust gases up to the base of the intake manifold to help the engine run smoother at start-up. This manifold heat control valve on an inline engine performs differently than the heat riser valve on a V8 and does not create any additional backpressure.

When the exhaust manifold is cold, the flapper only redirects the hot exhaust gases. As the engine warms up, the spring expands and gradually closes off the flow of exhaust to the intake manifold's base. In the fully warm position, the flapper creates a smooth exit for the exhaust gases.

There is NO need to force this device to either the fully hot or the fully cold position. Make sure it can move freely and leave it alone.

Frank