Timing a 360

[Paul G]

I have messed with everything else, time to play with the timing. The 360 runs much better now than it did when I got it. I put a weaker spring in the secondary vacuum actuator rather than the screw that was in the secondary linkage, it seemed to help some. Proper idle adjustment, Firecore wires and a carb cleaning made a world of difference.

It still vibrates a bit inside the car at idle and when just starting off. I think it has a bit of cam in it, but don't know for sure. I don't have any build specs on the motor. I can see gold roller rockers through the oil fill hole in the valve cover. That is probably a hint of what might be inside. Has an MSD 6 box. I need to change the plugs. They are a light tan color. Look decent actually. They are Autolite 64's. Why Autolite?? Thinking of a set of E3.46's. They cross reference to Autolite 64.

She is a tire roaster as is  . Does a wicked burn out  , has 3:90 gears . But is there more   What is the optimal timing for a 360? I have not even checked to see where it is set at right now. Sorry... Might have some time this weekend to play with the timing. Just wondering what usually works best on a 360.

BTW, she pulls hard to 5500 RPM, then lays down. With the 750 Holley I would think it should spin up higher than that. You think?

[Cooter]

It would all depend on the rest of the combination as to how far it "Pulls" up to...Yes, you have enough carb, but you might not have enough cam/valve spring/head, etc...

Sounds like it has a very small cam..Maybe a step above stock if you can't hear it "lope" at idle very well...Typically, this type cam will "Lay down" around 5500...

[71383bee]

for timing As a general rule I always set total timing at 34 and then idle it down to check where it comes in at and where initial lines up. 

My experience is that most mopars like between 34 and 36 BTDC for total and around 16 to 18 for initial all in around 1500 to 2000 RPM.

Start at total and work back from there.  You might need to have the distributor curved which is a good thing to do....

[firefighter3931]

Good advice posted above. If the heads are stock and the cam is modest it will fall off at 5500 or so....pretty normal. 

Timing (initial) for most mild builds should be in the 16-20 range at idle and 36-38 total all in by 2500. As mentioned you might have to recurve the distributor to shorten up the mechanical advance. Try using a vacuum guage and advance the timing until you reach the highest amount of vacuum. This will be your starting point. As the vacuum increases, so will idle speed so you will have to readjust idle screw. Check the total timing and see what you got and report back. 


Ron

[Paul G]

Just a question. Vacuum advance is mainly for economy right? Most times it just causes pre-ignition. End up turning the screw inside the advance unit till it barely operates. Whats up with that?

[71383bee]

I don't even have vacuum advance on my dizzy. 

It is mainly for part throttle economy.  The idea I believe is if your say cruising on the freeway with the throttle cracked open a bit.  the vacuum created by the motor is fed through a metered port on the carb that pulls the VA dash pot on the dizzy.  It adds timing into the motor to make it burn less gas and therefore be more efficient.  Since most hi-po applications deal with rapid acceleration between idle and WOT there is really no need for VA.   

I am sure its more technical than that, but that is the way I understand it. 

Some people I know try to us the VA to add additional initial timing.  A common trick is to connect the line to a manifold source that will pull a vacuum signal at idle.  (ported sources do not)  This will add more initial timing to the motor at idle and as you have seen motors like timing.  I  have always seen this as a sort of band aid to the problem rather than getting the distributor professionally phased and curved.  It works, but its not as effective as a good curve IMHO.

Don at FBO in Oregon did my 383 years ago now and since then it has ran well.  www.4secondsflat.com