Hi all
my first post. I have a JENSEN Interceptor with a 383. On electronic ignition MSD blue. NGK iridium plugs. I installed a tuneable PSV valve a few moths ago and my plugs are soot). As I was checking everything I checked my total timing, I have never done this before, I only set my initial timing at 10 BTDC. I have always thought that I lacked some beef when under heavy load (right foot planted) but after checking my total timing i was surprised to see it at 50BTDC (verified). Looking at the specs of the distributor it should only add 21 degrees of mechanical advance. I may have several issues that I am looking at:
PCV may be pulling through oil (I’m not happy with my catch can) plugs may be incorrect temp wise, and issues with carb (performer 750) however the timing has me puzzled. If anyone can provide guidance on any of these issues or thoughts on my set up I would be most grateful. I’m in Scotland so there isn’t many people around with the experience needed.

 

Did you pull the vacuum line from the distributor before checking the timing?

 

To set initial timing yes. Total timing was connected

 

You leave it unplugged for total timing also because you need to know the amount of mechanical advance in the distributor. Once you have that wohed out you can look at the vacuum advance for highway driving...
full mechanical advance should be between 35 and 38 depending on how the motor is built....

 

Wow that high. I thought it needed to be around 35. The engine was rebuilt 8 years ago but it was kept stock. So I will recheck with vacuum disconnected but I thought that vacuum effectively gets replaced by mechanical under load I.e. my reading was at 3000rpm with vacuum connected. Is that something to worry about or I'm in the ball Park?

 

My mistake 35 to 38 is where I would start if you using cast iron heads. The **** pore heads on the BBM requires more timing. So of the quickest and fastest times in my Plymouth are with the timing at 42 degrees but on the dyno 38 is the number making the most power. However if you were to use aluminum heads total timing should be 33 to 35 degrees advanced....

 

Stock cast heads so I guess I will try low 40s, tks.

 

My 2 cents.....
I like the 10* initial.. But without the vacuum advance... I would like to see 28* mechanical advance.... Bring the total to no more than 38*
I agree that 50* is way too much regardless your using mechanical or vacuum advanced. At lest not on a simi stock motor.

 

I have the distributor out to inspect it and have a set of springs winging its way across the pond for me so I will have to investigate further to see why I’m seeing such a high reading.

 

Keep us posted...