New here :-) Just a quick hello from the Netherlands!
I decided to join this forum as i'm having some technical questions regarding my '63 389 engine.
Unfortunately i'm not driving a GTO or Lemans (great cars!), but a 63 Pontiac Bonneville with a pretty serious engine for a fullsize car in my opinion.
Decided to join the forum as it looks like there are more Pontiac performance freaks over here
Not sure, but if i'm right (correct me if i'm wrong) my 389 engine is also being used in later models includes the GTO/Lemans. Some specs:
1963 389 engine
4 barrel (AFB Carter)
original 797 heads (62cc)
10.25 or 10.5:1 compression ratio.
Shop manual says something about 330HP and 430ft.lbs torque, not bad for an engine of almost 50 years old.
Engine is still fully original, but half a year ago I started to have issues with the stock point distributor. As it was quite rusty I decided to swap it with a new HEI ignition.
At this moment i'm busy with recurving my HEI, as the cars runs on propane (since a couple weeks an Impco 425 LPG carb directly on the intake instead of the petrol carb.
Cars runs great, but i'm missing some performance which I know can be found in the ignition. The strange this is that when the engine has a total mechanical timing (initial + mech) of 32 degrees it starts to ping @ WOT which is quite strange as propane has about 110 octane - a lot more than the average pump gas. Propane likes (better performance) less total advance, but so far I know it shouldn't ping earlier than petrol.
Does anyone know the default timing curve / total advance for a 389 engine with it's original points distributor? My shop manual says only 6 degree BDTC, but nothing regarding the total timing. The slots in my point distributor seem to be shorter compared to the HEI - it looks like it has less mechanical advance.
I thought Pontiac engines @ pump gas did like about 32-36 max timing, but maybe it's different with my engine.