Dwell angle

Post by **Phil-tq** » Tue Mar 22, 2005 2:11 pm

Can any of the tech heads out there tell me what the dwell angle should be for the correct points gap on a standard 1098?

I would also be interested to know how you calculate it.

Many thanks

Post by **Cam** » Tue Mar 22, 2005 2:26 pm

Ummm........ well, to be honest not many people bother with it as the points gap method is often good enough to set the dwell. I think 60 degrees tends to be a universally accepted figure mostly as it is 2/3 of each quadrant of the dizzy.

On a standard 1098 I doubt you will notice ANY difference if you set the dwell out by 10 degrees (plus or minus). They are not that critical.

How do you mean calculate it? From what? You can measure it (dwell meter, bulb, or oscilloscope), but the workshop manuals give the points gap.

The dwell is how many degrees the points are closed, so as long as it can open and close with sufficient time to allow the coil to charge and discharge magnetically then all will be fine. The problem is if you are running VERY high RPM and it does not allow the coil to charge / discharge correctly. This situation won't happen with a standard 1098 though.

Post by **Alec** » Tue Mar 22, 2005 3:20 pm

Hello Cam,
60 degrees it is + or - 3 degrees, and I note that I have penned in alongside that, 63 to 70% which is what my meter reads in, I don't know why.
Incidentally I haven't used feelers in years for points, I eyeball it then set it with the meter.

Alec

Post by **Cam** » Tue Mar 22, 2005 3:38 pm

Oh that's good to know, Alec.

The % is the mark/space ratio and 60 degrees is 66.666% so 63% to 70% is 54 to 63 degrees.

Incidentally I haven't used feelers in years for points, I eyeball it then set it with the meter.

Yeah, I must admit - I use feelers, but a lot of people used to use a thumbnail to set it which was even less accurate!!

Post by **Stig** » Tue Mar 22, 2005 4:56 pm

I used to set it by using a dwell meter with my old distributor as it had a bent shaft and gave different gaps for each of the lobes!

Got a replacement and now also have the Magnatronic gizmo now so it's not an issue any more.

Post by **Cam** » Tue Mar 22, 2005 5:02 pm

Stig28 wrote:I used to set it by using a dwell meter with my old distributor as it had a bent shaft and gave different gaps for each of the lobes!

Yes, the reading jumps all over the place!

Got a replacement and now also have the Magnatronic gizmo now so it's not an issue any more.

Same as me. I use an Aldon Ignitor on my 4-door car, so I don't have to set anything (except timing). Still got the old points on everything else though.

Post by **rayofleamington** » Tue Mar 22, 2005 5:19 pm

I used to set it by using a dwell meter with my old distributor as it had a bent shaft and gave different gaps for each of the lobes!

The dwell angle would have been the least of your worries! If the cam was running off-centre you would have had different timing for each cylinder (the cam opens the points and that makes the spark). Whether the coil had the perfect amount of time to recharge or not doesn't help with the spark happening at the wrong time.

Post by **bmcecosse** » Tue Mar 22, 2005 8:22 pm

More likely just to have been worn dizzy bushes rather than bent shaft - but similar effect. Doubt there would be much effect on a standard engine though.