A quick question about dwell

Is the cam angle in the distributer equal to what the dwell should be, e.g. 32 degree angle=the dwell?

Thanks
Chris

 

I think the dwell is the amount of time the points are open and then close. So say the gap busts open and you can open and close the gap until you find 32 degrees reading on the dwell meter? Basically, the cam angle is the bump open and the gradual drop closed of the points. How you can measure the gap is not the theory of the cam angle, if I explained it correctly?

 

so is that a yes or no haha? if no then what do you think I would look at (I'm useing a motors manual for a 54 chevy) for my engines dwell?

 

dwell is the degrees the points are closed

 

if you are reading a tune up spec that says "cam angle" then that is indeed the dwell.

 

Thanks ffor the clear answer

 

Dwell is the period of time ( measured in degrees ) that the contact points are closed , allowing for coil saturation or field build up.
It is also measured as a average, which may on occasion cause a problem . Ex: V-8 engine could have a cam with rust or material on it causing a 28 degree on one single cam area and wear causing a dwell of 36 , a meter would show 32.
Only a distributor machine would show this inacuracy.. dwell is often called cam angle on some tune up charts like mentioned above.
Cam angle in reality is 360 degrees divided by the number of cylinders . A v8 cam angle would be 45 degrees using a dwell ( closed time between cams of 32 degrees.

If anyone is interested i can upload some pics of machine as a tech post maybe ??

 

an ignition scope will also show the dwell on each cylinder, if you have it set up to.

 

Ok so I'm dealing with a 6 cylinder (235) 360 divided by 6 is 60. My point gap is suppose to be 16 thousands, and my dwell is suppose to be 38 to 45
based on what you explained above, how do I get to a 38 to 45 dwell?

 

Yes dwell per cylinder on an ignition scope is the best, i just figured a scope ( or distributor machine) is something most dont own today.
We still teach scopes at our Indy training center but many dont have them.
Check us out at www.lindertech.com

 

You would just adjust the point gap with a dwell meter to get the 38 to 45 degree setting. Typically you would set the low number allowing for wear as mileage occurs to wear into the 45 deg range.
Also keep in mind that the distributor is a half speed of the crank devise and for each degree of dwell the engine timing changes 2 degrees. Timing must also be adjusted with new points etc.

 

Ok so if I have the equation down right, its 360 for the cam dived by the number of cylinders (6), take 10 degrees off for each side of the cam lobe and I end up with 40 which is my target cam angel. Am I following you right on this?

Now you say for each degree of dwell the timing changes 2 degrees. Is that 1 degree down on the dwell retards the timing by 2 degrees?

 

yes, that's right.

 

I MISSPOKE IN REGARDS TO DWELL ADJUSTMENT.
Dwell is adjusted to the high number allowing wear into the lower number.
Thanks for the corrections etc.
Dwell would wear lower changing timing to the retarded side as the cam and rubbing block wears.

 

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.....AND always use a dab of the correct dist cam lobe lubricant.....H ...

 

DAMN! I love this place!

 

Ok thanks, this has been very helpfull!

 

Bringing up this old thread need the dwell specs for a dual point Accel 371007 dist for a 327 does anyone know?



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I could be wrong, but I don't think so. When you add a degree of dwell, you are actually adding 1/2 degree on the points close and 1/2 a degree on points open. Only points open affects the timing. Therefore adding 1 degree of dwell will cause the timing to retard 1 degree, not 2.

 

You have 60 degrees of distributor rotation between the lobe high spots. You want the points to be closed (dwell) 38 - 45 of those degrees. If you set the dwell at 45, the points would be closed for 45 degrees of distributor shaft rotation, and open for 15. 45 +15=60

 

Thanks


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Any good source to purchase a new dwell meter. I have bought 2 off web - when they arrive - do not work.

 

I found this craftsman still in the box in my late father’s shop luckily it had the instructions took me awhile to get it set up properly in my lathe with a battery and an old coil Now the dist can go back in customer car

 

Be sure to use a ballast resister when using this method. Most points/condensers won't handle 14V.

.bjb