Timing Question

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64X2

64X2

Mohel at your service.
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Ok, so I have been unable to rid my engine of the dreaded pinging under load. I have changed springs and opened the slots to bring the timing in even later. All this to no avail, so I am now at the question. Is it possible with the overdrive 4 speed combined with the 2:76 geared rear axle, plus a 26 inch tire that I have such a high gearing that the engine is not got enough RPMs when all the timing comes in and the engine lugs, it can't use the available power quick enough and put it to the road to avoid pinging.... The car when you get it on the hi way will run 80 mph and the engine is only turning roughly 2100 rpms, and seems like there is no end to how much top end I have. Does anyone think that if I change the rear gear to a 3:23 or more this would help or cam change????????
this is what is in the car now it is roughly a 8 to 1 compression motor...

72 318 Block .30 over
79 318 Heads, not sure of the casting number think they are 72 cc chambers
1.88/1.60 valves
.23 head gasket
Purple cam 276/284 .444/.453" 112 degree
LD4B Edelbrock intake
650 Edelbrock carb
Windage tray
Double row timing chain
Mopar Electronic ignition with and orange ECU box

Thanks in advance.........
 
what is the initial timing set at (timing at idle)? What is your idle rpm set at? How much mechanical advance do you have it set at and at what RPM, are you running vacuum advance or is this blocked off? The only reason why it would be pinging under load (if the initial and mechanical advance are setup correctly) is if you have too much vacuum advance coming in. With the rpm you mention you shouldn't have reached full mechanical advance yet. probably should be in around 2500 rpm. Do you find it still pings if you block off the vacuum advance canister? Does it ping if you put your foot down at low rpm (no vacuum)?
 
I am not running the vacuum advance as it seems to make no difference. I am not sure what my initial timing is, the slotted bar is marked 15 ,at idle the timing light shows 32 degrees. My timing comes in full minus vacuum advance at 2200 rpm. When u accelerate from low rpms it pings once rpms are up no ping. I have tried 87 89 and 93 octane it still make no difference. I have timed it from 28 to 36 degrees and I either get ping or complete lack of power.
 
Cylinder pressure is 145-150 across all cylinders
 
you also need to make shure you have the vaccume hose on the ported side of the carb and not full port yaccume it will have vaccume at all times to check it pull off the hose put your finger over port if it sucks against your finger at idle its full vaccume plug this one off and put hose on the other side of the carb hope this helps
 
Not sure what you mean with "the slotted bar is marked 15" but you mention at idle the timing light says you have 32 degrees advance. I assume this is at around 700 - 800 rpm correct? That would be way too much initial advance and it would surprise me if you didn't have any problems getting the car started without any starter kickback.

Are you sure the timing mark on the dampener is correct? Just make sure the dampener hasn't slipped by checking if the 0 mark on the timing tab matches up with the groove on the dampener while the number one cylinder is at Top Dead Center (TDC). If you want to make absolutely sure it is correct you could use a piston stop.

The initial should probably be more like 14 degrees at idle and around 32-34 at full mechanical (2200 rpm). Have you tried setting the mechanical timing to 32? You can do this by bringing the idle RPM up to 2200 rpm (your full mechanical) and then set the timing to 32 with your timing gun.

Running the vacuum canister helps out with getting better fuel mileage during part throttle (high load). It ads timing when the manifold vacuum is high (part throttle) to help out with a better combustion. It also helps out with a part-throttle bog where the engine needs more timing before the full mechanical has come in. But since your car is pinging at low rpm, you already have too much timing in so adding the vacuum advance would only add to the problem.

Have you tried setting the timing not with a timing gun but by the highest manifold vacuum reading at idle (with the vacuum advance blocked off)?
 
if its pinging,its to far advance,need to back off the timing till theres no more pinging or run better gas
 
You also mention you "changed the spring and opened the slots to bring the timing in later", opening the mechanical weight slots only allows the advance so swing out further and therefor adding even more timing.

I would try to set the initial timing to where the manifold vacuum is the highest. Set the idle rpm to around 700-750, make sure the vacuum advance is disconnected and all vacuum ports are blocked off. Hook up a vacuum gauge to a manifold source or hook it up to the carb but make sure it is hooked up below the throttle blades (manifold not ported).

Loosen the distributor and move it to where you see an increase in manifold vacuum (you might have to retard it if you have the initial set too high). While moving the distributor the rpm will also change. If the idle rpm changes by more than 50 rpm set it back to 700-750.

You'll notice the vacuum will climb until it reaches its max potential, this is usually where the cam wants the initial timing to be. (again make sure you get this reading at 700-750rpm). Check with the timing gun what the initial now is.

Depending on this number you have to either make the slots longer or limit the mechanical timing slots. Most likely they need to be limited since you are running a non-stock cam. You might also want to bring the springs in the distributor back to stock before you start with any of this.

Sorry about the long write up, but hope it helps you out some.
 
I also have wondered about the harmonic balancer and timing marks slipped. When you bring the number one piston up to top dead center the balancer shows it's zero for zero. My idle is right at 750 RPM. I am using the ported vacuum on the carburetor. When I switched from pertronics to Mopar electronic ignition with the orange box this is when most of my problems started. I pulled another distributor out of the junkyard to use for the car for my electronic ignition conversion as the old distributor was worn at the shaft and the one that I got from the junkyard had no slop in it at all.
 
I have used the vacuum gauge instead of the timing light to try and set the timing also and even at highest manifold vacuum I am still having the same problem
 
64X2 said:
I also have wondered about the harmonic balancer and timing marks slipped. When you bring the number one piston up to top dead center the balancer shows it's zero for zero. My idle is right at 750 RPM. I am using the ported vacuum on the carburetor. When I switched from pertronics to Mopar electronic ignition with the orange box this is when most of my problems started. I pulled another distributor out of the junkyard to use for the car for my electronic ignition conversion as the old distributor was worn at the shaft and the one that I got from the junkyard had no slop in it at all.
Click to expand...

I don't know how you are determining the piston is up, but it is PROBABLY not accurate enough, IE did you use a piston stop, or something like a stick down the hole?

Does the car use ANY oil?
 
I also confirmed TDC when the heads where off and the car is not a oil burner. I am corn fused to say the least.

67Dart273 said:
I don't know how you are determining the piston is up, but it is PROBABLY not accurate enough, IE did you use a piston stop, or something like a stick down the hole?

Does the car use ANY oil?
Click to expand...
 
64X2 said:
I also confirmed TDC when the heads where off and the car is not a oil burner. I am corn fused to say the least.
Click to expand...

OK, but what I'm saying is, what method did you use? If you used a piston stop or dial indicator, OK. But if you just simply "brought a piston up" and sort of eyeballed it, that is no where near accurate.
 
I figured when it was at top dead center that the damper was close to zero and only maybe two or 3° off at the most and would work out once the vehicle was running and timed. With it being a fairly stock motor I didn't think the two or 3° difference was going to make that much of a difference in the timing. Which it hadn't with the old distributor and pertronics. Ever since I switched to a new distributor with Mopar electronic ignition and an orange box this is when the problems started. So I'm at a loss to come up with an answer why it still pings.

Still scratching my head over this. I am obviously overlooking something just not sure what.


67Dart273 said:
OK, but what I'm saying is, what method did you use? If you used a piston stop or dial indicator, OK. But if you just simply "brought a piston up" and sort of eyeballed it, that is no where near accurate.
Click to expand...
 
are you sure it's pinging and not a leak around the exhaust manifold? i've had leaks before when i had my 340 dart, around the headers. under load they would be noticable but not at high rpms

if you are sure it's real ping, maybe swap out the orange box for a regular chrome

also make sure your plug wires are sound and the distributor cap does not have a crack.
a hairline crack in the cap will cause all kinds of weird stuff, you never know.
 
"I keep adding advance, and it keeps pinging"

Everything you have described is too much total timing. Opening slots in the distributor adds timing. Huge initial timing number like 32 degrees only work with very limited timing in the distributor.

I will take your TDC verification at face value. So what is your total timing? This is easy to check, either with timing tape or an advance adjustable light.

Warm the engine up. Connect your timing light. Raise the engine rpm to 4000. What is the timing?

Total timing over 40 degrees is iffy.

Test for total timing, and post the number.

B.
 
With 145-150 PSI in the cylinders, I suspect your compression ratio is higher than you think. I'd start with initial timing at 10 degrees at idle with vacuum advance disconnected. Check the timing from idle to 2500 and see what the light reads. If you're cruising at 2000 RPM, you'll want about 10-15 degrees of mechanical advance at that RPM. Connect the vacuum advance and see what the timing reads at the same RPM's. At 2000 RPM you won't want more than about 25 total. That reading can go 5 degrees either way depending on your actual compression ratio. It might take a little trial an error to dial it in.
 
64X2 said:
I have used the vacuum gauge instead of the timing light to try and set the timing also and even at highest manifold vacuum I am still having the same problem
Click to expand...

so at the highest vacuum reading, how much initial timing does it show (at idle)? Now bring the rpms up until all the mechanical is in (you mentioned at 2200 rpm) to make sure just bring it up to 3000 rpm, now check with your timing gun, how much timing does it have now? This should probably not exceed 34-36 degrees. The fact that you have enlarged the weight slots means it is allowing too much mechanical timing, I think that is where your pinging is coming from.

Since you changed the ignition system, are you sure it was all done correctly, meaning no electrical issues (wiring), cracked distributor cap (like mentioned), faulty ignition wires, wrong coil, etc. Do you have the correct ballast resistor hooked up?

You mentioned earlier that you aren't running a vacuum advance, but in a later post you mention it is hooked up to the ported side on the carb. So are you running the advance canister or did you block it off?

When you set the timing it has to be done with the vacuum advance disconnected and the port that it was connected to blocked off.

Let us know what timing numbers (for initial and full mechanical) you got with the highest vacuum at idle with the vacuum advance disconnected.
 
I have 12 1/2° initial advance at 750 RPM. The vacuum is 16 1/2 mmHg at Idle. The timing runs out at about 2250 RPM and is right around 55° or full advance minus the vacuum advance. When I did use the vacuum advance it was plugged into ported vacuum. When I installed this distributor I found that it did not work with the vacuum advance as there was no change in the timing with the vacuum advanced canister. I found unhooking the ballast resistor and running straight 12 V to the coil the car runs much better ,I do have a high-performance coil.
 
The distributor I put in the car was a fairly new distributor. I replaced the pick up and the reluctor wheel along with a new cap ,rotor new wires ,new plugs. I set the gap with a brat's feeling gauge according to Mopar's specs. The plug are gapped at 45 thousandths.
 
Your initial plus mechanical is 55 degrees at 2250 RPM? Way too much advance.
 
It seems like you have way too much mechanical advance coming in, that's why it is pinging under load. 12.5 degrees initial is pretty mild, my 360 likes 18 degrees, so for your engine you are probably right on the money for the initial.

The key is now to limit the mechanical advance so that you have a maximum of 34-36 degrees timing total timing (initial and mechanical but no vacuum advance). So if you have 12.5 initial then you need a max of 23.5 degrees centrifugal (mechanical) to get the total of 36 (again with vacuum advance disconnected).

The initial and total timing (initial + mechanical) work together as a team. What is happening with your setup is that when you set the total timing (no vacuum advance) to 34 then you won't have the pinging but the car is a dog off the line because the initial timing is around 0 degrees.

When you set the initial timing to 12.5 the initial timing is perfect but the total timing is way too much, creating pinging on acceleration. You'll need to set the timing curve back to stock (springs) and check what the number on the mechanical advance plate is.

Most likely if the distributor is stock it will have the number 11 on it, this is crankshaft degrees so it would put double that in as mechanical advance (22 degrees) 12.5 degrees + 22 mechanical is 34.5 degrees total without vacuum advance. Right on the money.

Once the initial and mechanical timing is correct then you can add the vacuum advance to help out with highway fuel economy. You'll probably need to adjust that to limit pinging on part throttle. I can help you out with than once you have the basic timing sorted out.
 
The advance limiter is stamped or bar with the slots is stamped 15 r.
 
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