It's always best to change 1 thing at a time and then test.
My new stock stroke 400 build
- Thread starter qkcuda
- Start date
Huge turnout at Ancaster, Dave. The guy was selling new parts and he actually had another distributor in a kit with the wiring harness and orange control box. Both were for B engines, what are the chances of that?
BSB67
Well-Known Member
……and for the secondary vacuum diaphragm spring, if et matters to you, the track is the only place to test it.
Yes, I know Don, but my garage time is limited, so I kept working. I can test the total timing without even getting into the secondaries.
When I took my engine builder for a ride he felt that I might be a touch rich, but I am not going to change the jets until I have a good baseline. I'm really interested in seeing if the change of timing stops my temperature creep at cruising speeds.
The track is on the agenda for next year, but our season is pretty much done here now.
I checked the new distributor out today. I set the mechanical advance to 35 degrees at 2500 rpm and found I had 25 degrees at 1000 rpm. I continued running it up to 3500 and it kept slowly advancing up to around 42 degrees. I left it like that with the vacuum advance disconnected and took it out for a ride. It ran fine with no obvious pinging, but it made my overheating problem worse. I checked a spark plug and it seems like now it doesn't have enough advance.
I ended up pulling the initial back to 20 degrees and hooked the vacuum advance back up to ported vacuum. It looks like it topped out at 48 degrees total. I'm going to try running it like that and see how it acts, and if it helps the overheating issue.
Your distributor should be able to give you about 20 - 24 degrees of mechanical advance. It should start coming in around 1000 RPM and be "all in" by 2800 to 3000 RPM.
I had my Road Runner (with your old engine) at around 36 degrees total timing (initial plus mechanical, no vacuum). On the dyno, I actually picked up power reducing my total timing to 34 degrees.
Yes, the distributor I built for the 500 had specs like that. I had to unhook the vacuum advance when I ran it.
This distributor is supposed to have 22 degrees of mechanical advance. It appears that with one super light spring, I am getting some mechanical advance at idle. I should probably change out the heavy spring so the total advance comes in sooner.
I am going to try it as is right now since this car cruises at about 2500 rpm, so with the centrifugal advance not all in yet it may actually balance out by reducing the total advance at cruising speeds with the vacuum advance connected. If I am pulling over 3500 rpm I probably have my foot in it, so vacuum advance is not in play.
For Don Frelier I did make several full throttle blasts to check the secondary opening with the new spring and it is better and no bog. Now with the quick change top I can change springs in 5 minutes.
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