Dwell changes
Le Mans Master
Joined: Oct 2006
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Good point- my original TI distributor, the lower bushing was shaped like a football. It's a wonder that the upper bushing was still fairly good.
Thread Starter
Safety Car
Joined: Sep 2005
Posts: 4,213
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From: Orange County Ca
I rebuilt the dist. about 25k miles ago. I replaced the lower bushing. The top was good. I did shim the gear to get the correct clearence. Guess I'll have to check everything again.
Racer
Joined: Jan 2014
Posts: 425
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From: Jefferson City Missouri
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Former Vendor
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One test that is long forgotten by new mechanics, in regards to dealing with the old school distributors. How to check the distributor for bushing/shaft wear.... and that test is to attach a dwell meter to the distributor and bring up the RPM's. If the dwell increases the distributor needs to come out.
Last edited by Willcox Corvette; Mar 16, 2014 at 01:31 PM.
Tech Contributor
Joined: Aug 1999
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From: At my Bar drinking and wrenching in Lafayette Colorado
It's normal for dwell to decrease slightly as rpm comes up - it's one of the drawbacks of single point ignition systems. A 3-4 degree change may be excessive at 2000 rpm, but it's perfectly normal for dwell to decrease from 30.5 degrees at idle to around 29 at elevated rpm.
If I were you, I'd first install a good set of points. If your points spring is inadequate, is will decrease dwell at elevated rpm. Try a set of NAPA CS786.
Normally, if you have bushing wear or things "flopping around" from wear, you will see fluctuating dwell at any rpm - not just an overall steady decrease as rpm comes up.
Lars
If I were you, I'd first install a good set of points. If your points spring is inadequate, is will decrease dwell at elevated rpm. Try a set of NAPA CS786.
Normally, if you have bushing wear or things "flopping around" from wear, you will see fluctuating dwell at any rpm - not just an overall steady decrease as rpm comes up.
Lars