Pinging Problems

[petieg383]

OK I cannot get my 440 to not ping when I get on the gas. Here's the story, hopefully I'm just doing something wrong. Sorry I don't have all the info, but this is everything I can provide.

• What I know: 440 Engine, 915 heads with stock rocker setup, Manifolds and 2.5 Exhaust with Flowmasters, 4 speed with 3.23 gears. Weiand Action Plus Intake, Holley 750 Vac Sec Carb. I also have one of those 4 Second Flat discs in my Distributor to limit the advance. Timing is set at 18 initial, 34 total all in at 2800-2900. I have the vacuum advance plugged. It typically pulls down somewhere around 15-16 of vacuum at idle.
• What I don't know: Cam seems stock or a bump up but I don't know. It's not a roller or a solid or anything radical. Compression - No clue. I imagine with the 915 heads it's not low. Engine internals - Other then a steel crank I'm not sure.

I just cannot get this thing running decent. It putts around OK but there just seems like there is no power really in it. I know it needs some gear and exhaust but I'm supremely disappointed in the power. Just put in some NGK XR5 3332 plugs as well and I dropped the primary jets from 74 to 71 as the old plugs were black as night and carbon'd up something nasty. And that has made no real difference other than make it stumble more when I blip the throttle at idle.

I'm stumped and it's totally making me not want to drive the car. I was going to try a tank of 100 octane or some octane boost to see if that does anything, but I can't live with paying those prices for a tank of gas.

I welcome your advice.

 

[miller]

What year is the motor? What's the history of the motor...rebuilt?

Would help to know the compression values. Fuel, usually require 92-93 octane, something you have to live with, sporting a 440. Unless it's a slug motor, meaning how it's built.

 

[BSB67]

Check your cranking cylinder pressure.

Sounds like you have two or more problems. How does it idle

 

[hunt2elk]

Might have to lower the initial timing a bit if it is a stock cam. Does it run on when shut off, or does the starter kick back when starting hot? Run some fresh 91 octane gas. What distributor and springs are you running? Might have to recurve it to bring the advance in slower.

 

[moparnation74]

Just me guessing but I think you engine may have those stock slug pistons.....making low compression.....
The ad ons are nice but the compression is probably the killer here.....

If thats the case then milling the heads and intake may be an option......

First and foremost is SPARK, TIMING, FUEL........If that is set spot on and these issues are present. Than it is probably what I mentioned above.....

 

[67 coronet]

1) do a compression test to find out for sure what is going on there. not only for overall comp but for balance of cylinders.
2) what is the condition of the carb? i have seen dirty or pluged up carbs cause all the issues you are stating.

 

[Johnpat]

You say the plugs were all carboned up,then you replaced with new.Then you rejetted the carb to
71s.
Was it pinging before this??
If not you may have a vacuum leak causing it
to heat up causing your pinging.
That may be why it was jetted fat to start with,masking a vacuum leak off idle.

 

[Lelo 500]

Try backing off on you initial timing and leave your FBO plate setting the same. Maybe 12 - 14 initial. BTW... Have vacuum advance? Might try leaving unhooked and see if you pinging improves. If it's better but still pings back it off some more. Been going through the same thing with a 5.9 Magnum. Good luck!

 

[petieg383]

To answer all the questions in one spot:

• Block is '75. It's supposedly rebuilt. I don't know the internals other than it has a forged crank. I know this for sure because I replaced the oil pan gasket
• I ALWAYS use 93 octane gas
• When you ask how it idles, not sure what you mean. It idles at about 700rpm and it sounds good to me
• No starting issues, no starter kickback. It starts when it's hot as far as I know.
• Distributor is just a stock piece from Autozone. The spring kit I have came with gold, silver and black springs. I have a lightest and a medium in there now. The full advance comes all in by about 2800-2900. Previously it was coming all in by 3600 which I thought was way too late?
• The rest of the ignition is basic. Orange ignition box and it has a Petronix Coil
• How is LOW compression causing pinging?
• Yes it was pinging before I changed plugs and re-jetted carb.
• No I don't have the vacuum advance hooked up.
• I think the carb isn't in great shape

Should I really lower the timing that much? To 12 or 14?

 

[451Mopar]

I would start with pulling the spark plugs and checking cranking pressure. Photo of the spark plugs too. Check plugs for signs of oil getting into cylinders.

 

[Lelo 500]

For a 1975 440 factory timing is 10 degrees initial. Not saying that is what your needs set at. Just that a lower initial is not out of the question.

 

[Paul_G]

Should I really lower the timing that much? To 12 or 14?

Yes. You have to stop the knock before it damages something. I would try backing out some timing like suggested and see what it does. If you are at 18/34 now, taking out 6 degrees puts it at 12/28. That should stop the knock.

If it stops the knock, then try putting it back to 18/34 and put a stiffer spring on the weights to extend full advance to a higher RPM.

The engine may not like 18 degrees of base timing, may work better at 12. Or, it may be good at 18 base just wants the curve extended out some.

Keep the vacuum advance disconnected till you get the mechanical advance dialed in.

 

[petieg383]

Pulled the #3 plug. This is what it looked like after about 10 miles of driving right after I put them in and dropped the jets.

I’ll work on checking the cranking pressure.

I’ve lowered the timing to 14/30. I’ll see what happens when I can take it out if it ever stops raining!

 

[33 IMP]

Sometimes lack of quench will promote more pinging than higher compression with proper quench. Your 915 heads,being closed chamber should help with quench but if you have stock"rebuilder"pistons in it ,they may be up to .180 down in the hole.
Original 400 big blocks were considered complete dogs for the same reason, chrysler just moved the pistons WAY down in the hole to cut compression, killed the quench, they detonated with any timing, with retarded timing they

wouldn't pull a fat girl off a tricycle.
Everybody wants 400s now for a stronger block to make strokers out of, using proper quench they run!
Still, tuning can make a big difference, could easily be a carb problem. Do you have another to try?

 

[miller]

What distributor and springs are you running? Might have to recurve it to bring the advance in slower.

That will be part of it. Carb not in good shape? No help there either. Your compression value, going by what's in the motor, what it's built for... makes the difference. 915 heads?
Being honest here, it takes the right combination of parts, to make the engine act right. Especially these days, with today's gas.

The gas today is made for smog motors. Your overall combination of parts is mixed. Not saying it's not workable, but you have to figure out all you have, and in a nutshell, give it what it wants.

Mine is a 69 440 HP, built pretty much stock, slightly over cam, but also sporting a crossram w/a pair of 600 Eddys. Topped off with a mechanical dual point distributor, and stock 609 heads, stock HP exhaust manifolds. Timing is pretty near stock, base timing set, with the built in mechanical advance, 13-14, full in 35 @2500 rpms. What the heck is my point?
Mine doesn't even think about pinging.

It's a matter of the right combination of parts, and those parts set up right.

 

[33 IMP]

I think Paul Gs advice is spot on.

 

[BSB67]

Your plugs don't tell you too much other than something is not quite right. It might have nothing to do with the main jets.

 

[451Mopar]

Pulled the #3 plug. This is what it looked like after about 10 miles of driving right after I put them in and dropped the jets.

I’ll work on checking the cranking pressure.

I’ve lowered the timing to 14/30. I’ll see what happens when I can take it out if it ever stops raining!

View attachment 610598 View attachment 610599

Plug looks OK. Timing mark is at the curve of the ground strap, but since it is pinging you could pull timing back a bit.
Doesn't look wet from oil so that is good.
Looks a bit rich, likely from idle mixture, unless you pulled it after a hard drive.