timing/dwell questions

[mwmeador38]

well i saw a good thread on here concerning timing and dwell once but now i can't seem to find it again. i have a 66 chevy 283. i bought an old dwell meter
on ebay and when i hooked it up it said 4 degrees. i thought maybe the old thing didn't work or something. so i'm in the garage today and decide to try and set the dwell with it again. i turn the hex screw clockwise and get it to 10 degrees and the engine starts running bad. i loosened the distributor and turned it counter clockwise until the vacuum advance hit the back of the intake. it ran better but now that's where i'm stuck. so what do i do now? pull the distributor and turn it clockwise and re-stab it? then proceed to increase the dwell until i reach about 30? i don't want to get everything so messed up i can't get her running again but it looks to me like that's what needs to be done. any advice???

[Corts60]

pull your dist. Cap and set your points with a feeler gauge to .018. Fire the engine up and set your initial timing with a timing light. After that, with your dwell meter hooked up, you should be ballpark around 28 degrees dwell. You want to be around 28-32.
Posted via Mobile Device

[mwmeador38]

i set the point gap many months back (before i had a dwell meter) but now the dwell meter is reading 5 degrees. i can't figure out if it's accurate or not. i've never had the distributor out of the engine but it appears it is stabbed in the wrong spot. if i dial the points up past 10 degrees the engine will die and i can't advance the distributor any further without pulling it and re-stabbing it.

[fleetsidelarry]

Originally Posted by mwmeador38

i set the point gap many months back (before i had a dwell meter) but now the dwell meter is reading 5 degrees. i can't figure out if it's accurate or not. i've never had the distributor out of the engine but it appears it is stabbed in the wrong spot. if i dial the points up past 10 degrees the engine will die and i can't advance the distributor any further without pulling it and re-stabbing it.

First, I'd do as Corts60 said and check/set the gap by feeler gauge (make sure the points are filed flat). Then re-test with your dwell meter to see if it's accurate. it may not be, or may not be on the correct setting. the feeler gauge method is more reliable than an unknown meter.

if it turns out you have to move the distributor (or move the plug wires around), then you'll just have to do it

[jocko]

key point: make sure when you check the point gap that the rubbing cam is on one of the 8 high spots of the rotor shaft - if you're measuring .18 gap with a feeler and reading 5 deg dwell, something taint quite right in the setup.

[Rufton]

I would rotate crank to #1 TDC compression stroke.
Confirm timing marker is correct (indicating TDC).
Pop dist cap and confirm rotor positioned correct relative to #1 plug terminal.
Then judge if dist needs re-stabbed.

[mwmeador38]

Originally Posted by Rufton

I would rotate crank to #1 TDC compression stroke.
Confirm timing marker is correct (indicating TDC).
Pop dist cap and confirm rotor positioned correct relative to #1 plug terminal.
Then judge if dist needs re-stabbed.

but it wouldn't even be running if the distributor isn't pointing to number one at tdc would it???

[Rufton]

Originally Posted by mwmeador38

but it wouldn't even be running if the distributor isn't pointing to number one at tdc would it???

The engine can still run if timing is a bit off.

The exercise is to determine if timing pointer, timing chain/gear and dist is in correct position.

Sometimes dist is stabbed on wrong tooth which is fine unless dist can't be turned to desired timing due to bumping the firewall, etc.

Sometimes the timing gear is off a tooth which will affect engine performance.

[tincan1966]

Realistically, there is no wrong #1 position for the distributor, it can be anywhere you want it. The engine won't know the difference. All that is necessary is to make sure everything is in alignment, as mentioned above and that the key components are in good condition(ie timing chain/gears, etc.)

Something no one has mentioned is the condition of the lobes of the distributor itself, that actually open and close the points, or the bushings in the distributor, which if worn, can allow side play of the shaft and affectively change the point gap.

Unless you are dead sold on staying original, I'd recommend installing a newer HEI elctronic distributor, which will give you a crisper spark, better driveability and better starting. There is minimal work involved in the installation/conversion. You will also need to re-gap your plugs or possibly even replace them with a higher heat range, depending on your needs.

[Rufton]

One vote for keeping points on <5000rpm <5000 mile per year vehicle.

[Sharps40]

If you turned dizzzy points screw you adjusted dwell to 10 degrees not the timeing.

Sed the dwell at 28 degrees hot (vacuum advance disconnected) with yer dwell meter by turning the points screw.

Set the timeing on the balancer tab to 4 degrees advance by rotating the entire dizzy.

Then adjust carb mixture. Then adjust idle speed.

Reconnect vacuum advance and go drive
Posted via Mobile Device

[Sharps40]

Remember. Increasing dwell retards timeing.

Changing timeing has no impact on dwell.

So. Set dwell first. Timeing second. Mixture third. Idle speed last.

Since ya fiddled the timeing way off ya may have to start at #1 on TDC with 16 thou point gap to get the engine warmed up.

From there turn (prolly counter clockwise on points allen screw thru the window) till yer at 28 degrees swell. Then turn dizzy til static timeing is 4 to 6 BTDC. Should rin much better.
[size=1]Posted via Mobile Device[/siz

[geezer#99]

JUst to add a bit to what Sharps says about dwell.

THe dwell degrees and the timing degrees are two different things. Dwell degrees is a measurement of how long the points are open. On your 283 there are 8 lobes and 8 flat spots that the rubbing block of your points rides on. On the flat part your points are closed. When the rubbing block starts to ride up the ramp on the lobe the points start to open. When the rubbing block goes past the lobe and down the ramp on the other side to the flat and the points are closed that distance between the opening point and the closing point is called the dwell angle. Measured in degrees of rotation of the distributor. Usually 28-32 degrees dwell.

One tip.
If you can't fit a feeler gauge in the point gap use a paper clip. The wire thickness gets you close.

[indy66]

Originally Posted by geezer#99

JUst to add a bit to what Sharps says about dwell.
One tip.
If you can't fit a feeler gauge in the point gap use a paper clip. The wire thickness gets you close.

A matchbook cover also works for setting the points.

I'm having a similar issue as the OP, going to try to set everything tonight.

[geezer#99]

OOPS!! Oldtimers disease!
I 'splained that wrong. Dwell angle is the time the points are closed, not open.