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Is 91 the highest youy can buy? If so, and depending on altitude, the timing should be on the low side. That said, depending on how Halifaxhops set the distributor up, initial should be 8 to 12*. Initial timing MUST be measured at a known RPM. If this requires buying or borrowing a...

Cleaner Air Package vehicles got distributors with mechanical advances that compensated for retarded initial. The retarded initial put more heat into the cylinder walls, insured more HC was burned up, and reduced CO. A graph illustrating the 273 CAP vs non-CAP timing in this post.

For a long time I thought this forum was for problems related to 'Mopar Performance'. In other words the service, products, and information from 'Mopar Performance'. Now I know its about, uh, well, not really sure, but anything that doesn't work and usually performance oriented (not factory stock).

Right, and to attain the mpg goal, at some iteration in the design planning the rpm and conditions (parameters) need to be determined. We know mixture density must increase under high load conditions, and ought to be moderately rich at idle for power. If the engine is going to be in stop and go...

Yes you can use an HEI module, if its a good one, and if you can keep it relatively cool. Same as the Chrysler ECU, make sure you can obtain a backup for the one you chose. A lot of junk out there these days. HEI controls the current to the coil. So no ballast resistor is used at all.

The most important thing will be the curves in the distributor. You're going to heat soak the engine in ways that a drag car never sees, and a street car only sees when hauling heavy loads in the mountains. It will not need or want the mechanical timing to be as advanced in the mid to top end...

No, Yes. Its bypassed with the start ignition circuit. Voltage is already low during start. It's in the coil feed in the running ignition circuit. As it cools off at higher car speeds (with more air exhange in the engine compartment) it resistance goes down a little compared with the car...

First. Maybe get a moderate to move this to slant six. This forum is for high performance modifications and wont get as many looks from people who might be able to help you out. Second. its really helpful to include the year, model, transmission, and accessories (like air conditioning). I...

Since you have Sun machine, plot out your distributor's advance curve and then the timing curve using a few initial. Compare that to the advance and the initial for a factory '70 440. Note the 2 bbl and 4 bbl often have difference advance curves.... Keep in mind that 1970 distributor will be...

Yea. It's a way to introduce the concepts but only goes so far. None of these carbs are sucking fuel directly from the bowl. Both the air and fuel is coming through a series of restrictions. Furthermore the air, when properly introduced, reduces the density of the liquid fuel - hence the...

You guys argue over the effect of air bleed at circuit initiation like its a yes or no. The reality is that it depends. Before messing with the HSAB to tweak the main circuit's start up characteristic, first make sure its doing its job at the top end. Then with emulsion correct and HSAB very...

Yep. makes sense. That's what I got from John Soemer from when he ran stock eliminator. But when they went to electronics they found out just what I posted here. lets revisit timing

Bottom Line. The most important thing to do is measure the timing from an rpm as low possible to as high as one expects to run the engine. Then make a decision on what to change or adjust. Initial and total are almost meaningless without knowing the rpm for each. ^^^ This is the biggest mistake...

Lets go over the different adjustments and what they do. Here's a governor (aka slot plate) installed with its springs and weights. 1. RPM advance begins depends on the initial spring force on the wieght. That spring force holding the wieght back depends on three things. a. Spring rate. b...

No. I disagree. A little more tension on the primary spring is generally no big deal, especially on a non-stock engine where its going to have more initial and little higher idle rpm. I've welded up slots on the outside only to file them open and redo it on the inside. If you want less spring...

Nope. Doesn't make sense. Yes welding the inside moves the weights outward in their initial position. This results in a little more initial spring tension. But that difference in spring tension is small and within the range it can be easily adjusted. Whether its better to weld the inside or...

Here's the first comparison. Dynomation's best timing vs. locked at 39 degrees. For the modelling, the factory 340 cam specs are as close as we could estimate and get Dynomation to accept. (back story here 340 cam specs?) Thats interesting! Lets try another comparison. Dynomation's best...

Mopar Manipulatin’ , HRM August ‘69 A more recent magazine dyno test of a '70 340 resulted in very similar in stock configuration. I generally don't trust magazine tests but having two tests, decades apart, provide the same results in stock suggests the numbers are probably fairly legit.

Turn the spring perch for the long looped spring so it contacts sooner. This will engage the heavy spring sooner and may slow the mid rpm advance enough to let you run 13 at idle. More likely to work if the inner end of the slot was welded than the outer, but either way its something you could...

For what its worth, here's little excercise I did using Dynomation 5 some time ago. One green line is what the program calls the 'ideal' timing for a 340 with a cam that has roughly 223/230 duration .505 lift. The other green line I got by trial and error reducing the timing every 500 rpm until...

You can do that! But for guys like ir3333 who are looking for power, that's why they're asking about the effect.

10* BTDC was the initial at 600 or 650 rpm for the 273 Commando engines. That's a good example because the idle were altered for cleaner emmissions. Techs could increase the initial or reduce it depending on altitude and fuel available if the owner wanted. Notice the timing advances at least...

I understand what you are asking. At a given rpm and load, the engine will make the most power when the spark is lead by enough time to develop maximum pressure when the piston can apply the maximum leverage on the crank. An engine that makes the most power at 3000 rpm with 34*BTDC will seem a...

Someplace I have photos of a fresh set of Champions. So proud of myself that I took before photos. Then I realizes it was a set with 5/8 hex and I've been sticking with 13/16. So I gave those away...

I'm no plug reader mark but the first ones look eroded or worn, unless they came that way. I'm looking at the strap. Not seeing it on the electrode. The second set is much sharper. Fresher plug? Your camera shots are pretty good. Its hard to focus in small with most digitals. If you can get...

Then I'm wrong, at least to some extent. If it bumped timing and maybe rpm ? then my assumption that is strong idle doesn't hold up. Worst case you could install a the idle solenoid like those used on some A/C equiped cars to bump the idle speed up under load.

OK. Then it does seem like the benefit of additional timing at idle is the effect on the idle circuit. I don't see why else it would run strong with 18* in gear with FI and not so with the carb. Need to find some Carter/Rochester guys that have run them on radical engines. Its done. Just less...

Was it idleing as well or stronger with the FI? If so did you have a map of rpm, MAP/Vac, and timing? The typical Carter idle system is a bit different than the Holley. The fuel to the idle port is shared sequentially after the trasnfer slot. The Carters usually have two restrictions and a...

I haven't looked at the AVS2. Are the metering springs controlling rods that gointo the main jets? if so, that shouldn't effect idle. Between that, and the drop of rpm from 900 to 800, it seems like the load with fans on is just borderline too much. Have you experimented with richer idle...

Get it to idle with initial timing of 17 - 18* and you can probably get away with the typical Chrysler PCV valve.