John Lewis Posted April 14, 2019 Report Share Posted April 14, 2019 Ok, apologies in advance for the dumb question but I have searched this forum and others and haven't found the answer so I am hoping for your answers and forbearance! I have had a couple of dwell meters kicking around my garage for years but never used them as I have always relied on just setting the contact breaker gap, but after reseting my contact breaker today I thought I would check the dwell angle as well. My question is at what revs should the dwell angle be set? With a contact breaker gap of 15 thou I can get 35° dwell angle at 1500 rpm but it varies with the revs, at tickover 500 rpm it's 30°. Any help gratefully accepted Quote Link to post Share on other sites
BlueTR3A-5EKT Posted April 14, 2019 Report Share Posted April 14, 2019 I too experienced this dwell change with rpm after using a dwell meter instead of the tried and tested feeler gauge in the points gap method. I fitted a Petronix Ignitor unit, instead of points - smoothed out the engine tickover and running. My distributor was sh*gg*d, but the Pertronix improved things, it was even better after Distributor Doctor rebuilt it and is now fitted with the Pertronix unit instead of points. (the points/condenser base plate assy is in the car ....just in case....) I'd say the dwell should remain constant, not change with rpm. Probably points mounting plate rocking and /or distributor spindle bearing wear. Cheers Peter W Quote Link to post Share on other sites
John Lewis Posted April 15, 2019 Author Report Share Posted April 15, 2019 Ah, thats useful, I will have another look at that, the distributor hasn't done that many miles so hopefully it's not that. Thanks for replying. Quote Link to post Share on other sites
Waldi Posted April 15, 2019 Report Share Posted April 15, 2019 I have observed the same, on several different engines. Thought it was caused by dynamic effects either in the distributor or the relatively slow analog measurement. Assumed the reading at idle was the one to use. Waldi Quote Link to post Share on other sites
John Lewis Posted April 15, 2019 Author Report Share Posted April 15, 2019 Thanks Waldi, I will have a look at the distributor and see if I can see anything wrong otherwise will assume it's the way things are and set it to be 35° at 1500 rpm as that's usual cruising revs. Quote Link to post Share on other sites
Waldi Posted April 15, 2019 Report Share Posted April 15, 2019 Hi John, this website indicates dwell should be set at cranking speed. https://www.thoughtco.com/dwell-and-timing-explained-even-more-4059400 Regards, Waldi Quote Link to post Share on other sites
John Lewis Posted April 16, 2019 Author Report Share Posted April 16, 2019 Thanks great, that's what I gone with. Thanks again Quote Link to post Share on other sites
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