Recommended timing 1972 Barracuda 360 w/ purple 509 cam

[ShadeTreeFixer]

Here’s the specs of my ride. What would be optimal initial, total timing?

1972 Barracuda
360 Chrysler
Over bored 0.03
Kieth Black Pistons
Mopar Purple Cam 509
MDS Distributor (light blue & light silver springs w/ purple bushing: estimated 19-20* of total advance)
Headman ceramic headers
Manual valve body tranny conversion 3600

My main question is how does the cam either affect timing or would need timing changes?


Also does the manual valve conversion require timing adjustments or is that not affected but requires timing to be precise?

This is a car that I purchased from a guy at a great price because it was making a grinding noise on the front passenger wheel. I though bearing so when I took it apart I found the new brake pad was installed backwards. And this was done at a shop!!!! Anyways I’m going through the entire car by principle.
Thanks in advance.

I set it to 16* initial and total was very close to 35*/38* total but the rpm’s would really bog at 900-1100. Almost had to get it to 12000 rpm at idle. That’s gotta be too much right. Maybe this is just a carb tuning thing or maybe my timing values aren’t correct for the installed pistons, cam, etc..

 

[Chryco Psycho]

IMO 16* initial is about right , although total timing is far more important than Idle timing .
I always time by ear to see what the motor wants , bring the RPM up to 2500 plus & you can hear the difference as the rpm rises until it stops a flattens out , I usually set timing just before it starts to level out .
I suspect it is more of a carb tuning problem

 

[Challenger RTA]

Just thinking simple. Air cleaner on when tuning? Choke working correctly?

 

[ShadeTreeFixer]

Ive been leaving off the air cleaner off. So I found a carb bolt washer(hard plastic) had split so I’ve replaced it with a aluminum one and now gonna see how it likes it.

 

[Mr Cuda]

Got to know what the compression ratio is, or at very least, the cylinder pressure.
A 509 cam in a std 360 with 8.2 CR is not going to run well.

 

[ShadeTreeFixer]

Got to know what the compression ratio is, or at very least, the cylinder pressure.
A 509 cam in a std 360 with 8.2 CR is not going to run well.

Compression ratio should be close to 10:9:1

 

[Challenger RTA]

There are fixed spec for every build. Vary from that and it wont work as it should or as you think it should. The fixed selected specs or parameters being carb,intake,head,valves,crank and pistons and cam. The cam being the heart rate of the engine is how it will breath. Yes the crank can be of a different design, stroke and crank layout. But that is a whole other thing.

They way to consider this is if you are selling apples sell apples. If you selling oranges sell oranges. I not then you just end up with fruit salad.
There members here that are very knowledgeable about this. Use it to you benefit.

 

[Ricks72Chlgr440]

Here’s the specs of my ride. What would be optimal initial, total timing?

1972 Barracuda
360 Chrysler
Over bored 0.03
Kieth Black Pistons
Mopar Purple Cam 509
MDS Distributor (light blue & light silver springs w/ purple bushing: estimated 19-20* of total advance)
Headman ceramic headers
Manual valve body tranny conversion 3600

My main question is how does the cam either affect timing or would need timing changes?


Also does the manual valve conversion require timing adjustments or is that not affected but requires timing to be precise?

This is a car that I purchased from a guy at a great price because it was making a grinding noise on the front passenger wheel. I though bearing so when I took it apart I found the new brake pad was installed backwards. And this was done at a shop!!!! Anyways I’m going through the entire car by principle.
Thanks in advance.

I set it to 16* initial and total was very close to 35*/38* total but the rpm’s would really bog at 900-1100. Almost had to get it to 12000 rpm at idle. That’s gotta be too much right. Maybe this is just a carb tuning thing or maybe my timing values aren’t correct for the installed pistons, cam, etc..

View attachment 131665View attachment 131666View attachment 131667

Does your distributor have vacuum advance? If so, is it connected to full manifold or ported vacuum? Bogging at lower speeds means the engine is not making enough power to be happy. This is especially true if you have heavy electrical loads calling for power (i.e. electric fan, A/C compressor). You likely need a bit more initial timing but you don't want to go over 36* or so on top. The MSD distributor uses a small bushing to limit total advance. You likely need to change that. By the way, I had a 440 that I could not get enough low end power to not want to stall when the A/C and electric fans came on. Engine had issues so I took it to the machine shop. Found the guy who built it did not degree the cam properly. The cam needed to be advanced 6* to get to the spec on the cam card. That really woke the engine up. I also installed the progression ignition setup so I could tune the timing from my phone. Big difference. Just FYI.

 

[toolmanmike]

3600 stall converter? Is that what you mean?

 

[Mr Cuda]

Ok. You have compression. Big cam, low compression was my first thought. It's a common mistake.
Make sure the primary throttle plate is not open past the transfer slot. It might take some tweaking to get the rear plate cracked open to get proper idle speed, with the primary plate in the correct spot. (Unless its a holley, then its easy)
You need idle control to get off idle response and prevent it from going flat at low speed.

 

[Xcudame]

I wouldn't break a new engine in with ceramic coatings. The coating will likely burn off!

Did you actually calculate the compression ratio with the KB pistons and the cylinder head combustion chamber and gasket thickness? Are you running KB190s (popup piston)? Unless you're running aluminum heads, 10.9:1 with cast iron heads will require higher than 93 octane.
Did you check valve to piston clearance?

Distributor have vacuum advance too? I normally leave that disconnected at break in because you want to run the engine at approximately 3000 rpm for roughly 20 minutes. Fine tuning comes after break in. What size and make carburator are you running?

Assuming that you did all the due diligence of engine design and everything is working together as it's supposed to be, 16° initial is a good starting point. It's hard to tell from your post if you already broke the engine in or not. If you did, I bet the header coating is toast!

I spend literally years designing an engine prior to buying one part. Even using a tried and true build that I've built before, I double check everything to ensure a known baseline.

 

[TIMINATOR]

Open chamber heads, a taller deck clearance, nonprojected tip sparkplugs, and thicker head gaskets require more timing than an optimized, tight quench area with a projected plug.
Aluminum heads require more timing than iron heads due to them transferring more combustion heat into the water jackets. A properly curved distributor requires less initial timing due to the quicker timing curve advance at higher RPM.
An abnormally lean or rich mixture requires more timing due to flame propagation.
Without more info, any opinions will only be a guess.
TIMINATOR