455 question
455 question
i finally got my 455 running pretty good,,my question is,,i dont have exhaust on it yet,,,just headers....when i goose the throttle and let off ,,i can see i flame come out of the headers,,is this normal,,i set the points at .019 and beleive the distri. timing is perfect,,it starts right up as soon as i turn the key,,,
Last edited by 1973olds98; Dec 1, 2010 at 03:33 PM.
Yeah the spark plugs are carboned up,,,,Ok so the flame is normal,,,My neighbors would love for me to get a exhaust system on,,,lol,,,,The dist. i put on was a stock remanufactured unit,,,I checked the points and made sure they were .019 like the chassis manual states it should be...It said with .019 that should give u a dwell off 33*,,,What would happend or sound like if it is to much dwell or not enough..So if i got the points set correctly is the dwell set-up or is that different..
I forget - why did you replace it?
The spec. is usually a range of 28-32°, and I usually go right for 30° in the middle. I practice, it probably doesn't matter, since the reason to set for a specific dwell angle is to leave the current on long enough before the spark to magnetically saturate the coil's core, but not so long as to cause overheating. In big American V-8's there's a ton of leeway in either direction.
The dwell angle is the number of degrees of distributor rotation that the ponts are closed.
In this case, you've got 30° of dwell on each of 8 cylinders, so
30° x 8 = 240° total time closed per rotation, and
360° — 240° = 120° total time open, or
open 1/3 of the time, closed 2/3 of the time.
The dwell angle is adjusted by adjusting the points gap. The points gap is not adjusted for its own sake, but in order to adjust the dwell -
points open too far = too little time closed,
points closed too much = too much time closed.
Since the rubbing block of the points wears with use, the points gap very slowly closes over the miles, reducing the gap, and increasing the dwell.
This is one reason why you've got to tune up the car every few thousand miles.
The opening of the points is the actual event that causes the spark to occur at the right time (not the rotor passing the distributor terminal). Since the points are opened by the action of a follower riding on a cam (that octagonal thingie inside the distributor), they do not open and close all at once, but somewhat gradually, and there is a certain instant at which the suddenly stop conducting electricity, thus creating the spark.
If the points gap is increased, then the points will begin to open sooner, and the spark will occur sooner, which will advance the timing.
If the points gap is decreased (by wearing of the rubbing block, let's say), then the spark will occur later, and the timing will be retarded.
So, to answer your question, if the dwell angle were too high (points closed too long), the timing would be retarded (provided it had been set with the dwell correct), and if the dwell angle were too low, (points open too long), the timing would be advanced.
BUT, if you adjusted the timing with the dwell wrong in the first place, there would be no noticeable difference at all. (If the dwell was WAY low, you'd lose high-end power, if the dwell was WAY high, the coil would overheat).
The beauty of the GM distributor is that you can adjust the dwell with the engine running, and so you never need to go through the annoying hassle of adjusting the points gap. Since the dwell is the actual quantity you need to adjust, and the points gap is just a stand-in for the dwell, and since the dwell is much easier to adjust than the points gap (especially since you're never supposed to adjust the gap in a used set of points because the natural erosion of the points with use makes the gap adjustment inaccurate), just adjust the dwell, and walk away with a warm squishy feeling about the whole thing.
- Eric
In this case, you've got 30° of dwell on each of 8 cylinders, so
30° x 8 = 240° total time closed per rotation, and
360° — 240° = 120° total time open, or
open 1/3 of the time, closed 2/3 of the time.
The dwell angle is adjusted by adjusting the points gap. The points gap is not adjusted for its own sake, but in order to adjust the dwell -
points open too far = too little time closed,
points closed too much = too much time closed.
Since the rubbing block of the points wears with use, the points gap very slowly closes over the miles, reducing the gap, and increasing the dwell.
This is one reason why you've got to tune up the car every few thousand miles.
The opening of the points is the actual event that causes the spark to occur at the right time (not the rotor passing the distributor terminal). Since the points are opened by the action of a follower riding on a cam (that octagonal thingie inside the distributor), they do not open and close all at once, but somewhat gradually, and there is a certain instant at which the suddenly stop conducting electricity, thus creating the spark.
If the points gap is increased, then the points will begin to open sooner, and the spark will occur sooner, which will advance the timing.
If the points gap is decreased (by wearing of the rubbing block, let's say), then the spark will occur later, and the timing will be retarded.
So, to answer your question, if the dwell angle were too high (points closed too long), the timing would be retarded (provided it had been set with the dwell correct), and if the dwell angle were too low, (points open too long), the timing would be advanced.
BUT, if you adjusted the timing with the dwell wrong in the first place, there would be no noticeable difference at all. (If the dwell was WAY low, you'd lose high-end power, if the dwell was WAY high, the coil would overheat).
- Eric
ok,,I replaced the wole dist. because i was chasing down while no # 1 wasnt firing,,To make a long story short it was a vacuum leak ,,,So basically i replaced every part of the ignition system..I need to locate me a dwell meter and make sure i have the correct dwell...Can spark plugs that are coated with soot, carbon,, be cleaned up and reused,,,i hate to buy another set since these are basically new
In fact, you may not even need to clean them up - the carbon will probably burn off after a good drive. If they're still firing, I'd leave 'em alone.
When I do need to clean them, though, I just give 'em a good scrub with lacquer thinner and a stiff wire brush, then blow 'em off with the compressor.
- Eric
... So long as you carry a spare set of points and condenser for when the electronics give up...
- Eric
edit: Unless, of course, you go with HEI, which is exceptionally reliable.
HOWEVER, with this guy, who's just getting his car going, I'd say get what's there working first, and THEN start making "improvements" once all the basics are together.
I would recommend Pertronix, from everything I've heard, but I'd spend my money to get the car running right before I'd buy that, then spend any extra money on extras like fancy ignition.
- Eric
edit: Unless, of course, you go with HEI, which is exceptionally reliable.
HOWEVER, with this guy, who's just getting his car going, I'd say get what's there working first, and THEN start making "improvements" once all the basics are together.
I would recommend Pertronix, from everything I've heard, but I'd spend my money to get the car running right before I'd buy that, then spend any extra money on extras like fancy ignition.
Last edited by MDchanic; Dec 5, 2010 at 12:19 PM.
Well i was going to just replace the points,,condensor,, i got a whole dist. unit for the same cost of the points,,condensor from autozone for 35.99,,My old one was pretty corroded and the wiring was brittle,,The new one came with a lifetime warranty..
i ddo have a HEI unit,,A cheap one I bought off ebay,,One of those china units,,,I did have it on when i first started it and notice coolant coming up ontop of the manifold above no #1,,It worked fine but the fit was sloopy,,You could see the whole unit wobble while the car was running,,,I picked up a multimeter today from autozone,,It has a tach,,dwell,,on it along with just about everything else i need,,,I also picked up a timing light which was free with my autozone reward card...anyways things guys for your help,,,,I will keep u updated,,,
Sounds like you're on the right track!
I'm shocked at a price of $36 for points and condenser, but then I haven't bought any in years (I've got a big pile of 'em I got cheap at flea markets).
Good luck!
- Eric
I'm shocked at a price of $36 for points and condenser, but then I haven't bought any in years (I've got a big pile of 'em I got cheap at flea markets).
Good luck!
- Eric
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