Well after alot of work finally got the newport running and back to normal, my question is I put one of the pertronix dist kits in, gapped it properly to .30. The car starts right up the only thing is when i put it into gear it wants to stall. We messed with the idle still did it. The idle also goes up and down, maybe the kit is no good or I need to mess with the mixture screws, any help would be appreciated, motor is a chrysler 383, did a cam upgrade, lifters, springs, 650 cfm carb. Stock distributor in good condition.

 

mrz -

Check for vacuum leaks.

Hard to say if it's set up correctly, since the cam upgrade may change timing or A/F requirements.

You didn't mention if you have a auto or manual tranny, depending on the cam, if you have an auto a higher stall converter may be in order.

Archer

 

It ran fine the last time we broke the cam in, had the original points installed that time. Auto tranny

 

Where is, or rather "where do you think" the timing is set?

Most cars can benefit from at least a few degrees faster timing than the book, within limits, as the distributor would have to be recurved otherwise

Have you checked with a piston stop to make sure the damper marks are correct? I do this on ANY unknown engine

Set timing first.

Get engine completely warm to normal temp

Set idle speed "roughly" and adjust mixture for highest / best idle, and readjust idle speed.

It might be you have a vacuum leak or are "lean."

 

I have the same cam on my 440 (plus larger valves and port work, plus a hair more than stock compression ratio) and the stock converter with no problems (in fact, I have descent amount of low end torque).


A vacuum leak would have affected the idle too, but its always wise to look for vacuum leaks (do you know how?).


Advancing the timing will most likely help too. With a high compression engine, you typically advance until you hear a bit of knock at WOT, then you back off. Or, you can use 89 octane, advance in short increments, and when you start hearing knock, then switch to 93 octane. You may have messed up your prior timing set with the electronic ignition.


When I finally reached a timing that I think its close, the idle went up a bunch, without adjusting anything on the idle screws. I may be able to advance further, as I suspect that my carb may be running a bit lean at WOT.


And ... by the way. I am not sure why people change to electronic ignition. Unless you drive 30K miles a year or something, and do not want to adjust points, or you have lots of cold starts in sub-zero conditions, I am not sure there are any benefits.

 

its close to 14 degrees btdc at idle. Well I just checked the comp cams website for the 268h xe when I bought it it said it worked with the stock converter now it says works with stock convertor but best with 1800 stall. I did turn the dist clockwise just a hair more not even and it seemed to run and idle a little better and I put it into gear and it didn't stall this time it wasn't as bad as before. No I do not know how to check for vac leaks still learning.

 

MrZ -

Two ways of checking for a vac leak.
One is with a vacuum gauge and second is with a water bottle.
The first will show a low or flaky vacuum with acceleration (a slightly "choppy" vac reading may be normal with that cam - not sure).
Spray water around the carb and manifold and any vac lines and listen for a change in rpm.

Archer

 

With that cam, you may be "out of" the idle transfer slots. Are the idle screws "all the way" out, that is, are they losing effectiveness? Sometimes you can adjust the rear barrels to open a bit, allowing the primaries to CLOSE betting back into the idle slots.

You need lots of initial with that cam. 20 BTC may not be "out of order." Use a vacuum gauge and time it for max highest vacuum at idle, reducing the idle speed if necessary to get it back down.

 

One thing better than water for checking for vacuum leaks is WD40 or other combustible or semi-combustible fluids (some like starting fluid). When you spray on a spot that may be leaking air in the manifold, the idle will go up for a little bit, as the combustible fluid increases the A/F ratio on that cylinder. The water may work too, by sealing momentarily. Spray around the carb, and around the manifold/head joints.

On adjusting timing ... I have the exact same cam on my 440. I have adjusted the timing to what I think is borderline knock at WOT, yet idle vacuum is too low (15 when fully warmed engine and oil). If I continue advancing, idle vacuum may increase, but I may have pinging at WOT. But since you have not reached the point of testing the car at WOT, may be that is a good way of adjusting timing (i.e., by maximizing idle vacuum), and then see if it is knocking at WOT (if it does, retard a bit). I think that the procedure of maximizing idle works well with stock engines, where the advance curve is developed for the particular set of heads/cam/compression ratio combination, but as you start modifying things, the optimum static timing for performance may not be the same as the optimum for idle.

Also, the reading of the timing with the light may be missleading. In my case, I suspect that the harmonic balancer has slipped, so that the reading does not mean much.

 

Both these have answers

1.....Sounds simple, recurve the distributor.

2....This fix IS simple. Use a piston stop to determine true TDC. Either re-mark or replace the balancer. While you are at it, either scribe the balancer with marks out to 50-60 degrees, or buy the proper size timing tape

 

So, sounds like I would need to reduce the centrifugal advance, so that I can have more advanced timing at idle AND more advanced timing at business RPM. That may also improve low end torque.


Right now, however, I have other issues to resolve (such as WOT mixture, and vibrations on 2nd gear, see my post on "440 build for Imperial".


Thanks.

 

This is exactly correct.

With a "mild" streetable cam, you don't want any more than 15-20 degrees mechanical advance or a bit more. Many performance distros come with 20-22 "out of the box."

With a "hot" street cam you might want even less. Something that will allow 15-20 degrees initial while limiting WOT to somewhere in the 32-36 range depending on engine. Some guys with hot cams are actually running "locked" distributors. "Back in the day" I had a 480 lift X 3XX ?? Sig cam in my 440. I had a dual point, and REMOVED the springs. The pints drag the mechanical back for starting, after that it was "full advance."

And this DOES depend on the engine, engine compression, head design, fuel (alcohol or not?) how hot the engine is operated, load and weight of the vehicle.

"We" just touched on this the other day. If you look at some of the performance engines of the late 60's but BEFORE smog controls, which means up through 67 NOT in CA, you'll find that the mechanical advance was surprisingly short.

If you DO read these bear in mind that both mechanical and vacuum specs were in DISTRIBUTOR degrees which are "half" crank degrees

Many mechanical advance "hats" are stamped with the distributor degrees amount:

http://image.moparmusclemagazine.com...ance_plate.jpg

This one is 15, which means THIRTY at the crank. This was off a 70's "smog motaw" with a really long, slow advance.

Here read this:

http://www.forabodiesonly.com/mopar/...d.php?t=178584

Note the hemi specs:



This was out of the 66 or 67 shop manual, I don't remember. They show 9.5 advance, so that means 19 degrees at the crank at 2800 CRANK RPM (The 1400 RPM is rotation at the distributor). Bear in mind this is for a FACTORY, STREET production car, not a race application, and with a STOCK hemi production camshaft.

 

Also keep in mind the dist only turns 1/2 the speed So 12 deg in the dist is actually 24 deg in timing So ideally you need 10 degrees in the dist (20 total) then 16-18 initial advance