DWELL Question

garyh

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My '66 Imperial,(440) has dwell of 30 Degrees at idle. If a rev the engine the dwell goes down to about 24 degrees. Is my Distributor worn ? A complete Tune-up was recently done. Dist. is original (2642252) with about 115,000 miles. any thoughts ? Halifaxhops are you out there. Thanks and i plan on keeping Points.
 

70bigblockdodge

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At speed points are not keeping up with point cam profile as well as slow rpm. If the car runs well it's not really a issue. If you were to want to rev the snot out of it it would likely spit and sputter(misfire). Now you know why they have stronger springs in contact points and dual points in high rpm/performance engines.
 

1970FuryConv

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My '66 Imperial,(440) has dwell of 30 Degrees at idle. If a rev the engine the dwell goes down to about 24 degrees. Is my Distributor worn ? A complete Tune-up was recently done. Dist. is original (2642252) with about 115,000 miles. any thoughts ? Halifaxhops are you out there. Thanks and i plan on keeping Points.
It helps if you put the at symbol in front of the persons site name. Ray @halifaxhops
 

CBODY67

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What you observe is completely normal. Set the point gap/dwell to spec and don't worry about it.

What CAN be an issue is cam lobe wear. If the point gap is correct by the dwell is not, then the cam lobe(s) have some wear on them. Worry more about the point gap spec, though, as that has to do with the ultimate durability/longevity of the point set.

IF you really want to get picky, use a dial indicator to check the point gap on EACH lobe. Which is where you'll see some differences between the various lobes, indicating wear, which will affect the dwell reading if the point gap is in spec. Which THEN makes the case for the more efficient and accurate electronic ignition system upgrade, FWIW. Be aware, too, that the particular breaker cam lobe you use to set the point gap might be different than the other lobes, which is what using the dial indicator really indicates significantly.

Be SURE to use the correct "point grease" to put on the rubbing block of the points!!! Many people in these modern times might not have any knowledge of such, especially since many brands deleted that little vial of grease from their point sets back in the 1980s. Mallory used to sell it in a larger tube, as did ACDelco. Specifically designed for point ignition point sets. Keeps the rubbing block from wearing down too soon and also keeps the breaker cam lobes from wearing too soon. Not greasing that rubbing block resulted from many electronic ignition kits getting sold in the 1980s, I suspect, as many related that the points in their older cars only lasted 8k miles, whereas we used to get 15k+ miles out of them in the 1970s and similar.

Just some thoughts,
CBODY67
 

Mr onetwo

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here you go Standard Motor Products SL-2 Standard Motor Lubricam | Summit Racing

smp-sl2_xl.jpg
 
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halifaxhops

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My '66 Imperial,(440) has dwell of 30 Degrees at idle. If a rev the engine the dwell goes down to about 24 degrees. Is my Distributor worn ? A complete Tune-up was recently done. Dist. is original (2642252) with about 115,000 miles. any thoughts ? Halifaxhops are you out there. Thanks and i plan on keeping Points.

Usually a worn lobe or distributor bushings will show dwell variations. the spec is 28-32 dwell and 17-21.5 inoz point spring tension. 24 is low usually what I see at rpm is it drops 1-2. Now store points? also did you gap them or use a dwell meter to set them.
At speed points are not keeping up with point cam profile as well as slow rpm. If the car runs well it's not really a issue. If you were to want to rev the snot out of it it would likely spit and sputter(misfire). Now you know why they have stronger springs in contact points and dual points in high rpm/performance engines.
HP spring tension usually goes around 24 and up in oz but then you can get serious high rev like accell f you ca find them at 36inoz.
 
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halifaxhops

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For lube you can also use pure silicone grease. I have some of the small packets that come with points if you need should go in a envelope if needed. $.55
 

garyh

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Now store points? also did you gap them or use a dwell meter to set them.
I used Vintage Filko point set and USA Condensor, I Gapped the Points .
Got 30 Dwell @ Idle and when revved Dwell went down to around 24 Degrees. Car has a slightly rough idle.This is an Original Never rebuilt,Distributor 2642252 on a stock 440. I will start a Private conversation with you .
 

halifaxhops

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Make sure the upper shaft is not bent and making the cam lobe wobble. Dial indicator or check the points gap on all e lobes see if there is a difference.
 

Gerald Morris

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Umm, could the distributor bushings be wearing thin? I disassembled the old one from the 383 I'm still running and those were so thin that the tap I used to pull them cut clean through. That one SAS* wobbled!
 
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