Need Opinions. Have nothing to compare to.
Yes, vacuum ports were capped off while checking initial and full mechanical advance at 2600 (33*)
RPM was about 750-800 RPM idle while checking initial.
Great. 750-800 rpm idle is decent for a motor with some cam.
As far as the total at 2600 rpm. My first reaction is Mopar Performance's recommendations are generally pretty close. This would explain the 'lazy' response. However you did some testing. Therefore at this point we can only assume there was a reason it didn't like or respond to more advance. Maybe the curve is too fast, or the fuel mix was off. We can see in the AFR curve that the mixture might be the reason.
Actually,... the vaccum advance was connected to the ported vacuum when I bought it, but it didn't run as well this way and ran hot. I have it connected to full manifold vaccum port now. It seems to run better and it is running cooler at idle and cruise now.
That makes sense. Now if you increase the initial timing to 16*, that should make the car less lazy, and you
may find the engine prefers ported.
I will have to get a vacuum T so I can check vacuum at ported vacuum port,
T Vacuum at the ported is manifold vacuum. The difference is only at idle. The ported vacuum comes from a hole just above the throttle blades in closed position. As soon as the throttles crack open, that port is exposed to manifold vacuum. Since there is no choke, you can see it easily by taking the hose off and squirting some carb cleaner in the port. Just be super carefull not to get that stuff in your eyes when looking down the primaries! Goggles are a good idea.
but I know the mechanical advance is at 33* without vaccum attached, so wouldn't my ported vacuum be contributing 4* at 2600 if the total timing (when connected to ported) was 37*?
Maybe I need to read back to an earlier post. So forgive me if I'm misunderstanding.
33*BTC at 2600 rpm. w/o vacuum advance
4* advance is added with 13 " Hg. (Vacuum)
When the throttle is floored, vacuum is close to zero. ( 1-2"Hg at most except in a restricted situation.)
When driving, the vacuum will probably be 14-18"Hg.
Coasting will be higher,
Part throttle will be lower.
Your vacuum advance canister will start to add advance at something less than 13" and keep adding advance with more vacuum. I'll post a plot of what this looks like after dinner.
Bottom line is you can add the 4* only when the vacuum is exactly 13".
It looks like a Road Demon or Speed Demon. It has a choke horn, but no choke installed, and mechanical secondaries.
Take some photos looking down as well as from the sides. I won't be able to tell you the model, but more important, we can see what type of boosters and adjustibility it was made with.
There were a bunch of threads about the Demon carbs on the old Innovate forum, and while they had some good features, most need some needed excorsizing. :lol: My guess, based on the dyno curves you posted, is that too much air is being bled. A lot of the newer Holleys and others do that too.
