After going through a couple mechanics the 440 was still pinging when it was warm and I get on it. So a few weeks ago figured a mechanically challenged dummy like myself couldn't do much worse than those guys and hooked up the timing light. What I found at idle with the vacuum disconnected was 0 degrees base timing and 20 degrees with vacuum hooked up. The vacuum is hooked up to manifold side. I don,t know the total timing because the tape only goes up to 20. After some trial and error I turned the base timing up to 10 degrees and turned down the vacuum so it now reads 15 degrees at idle with the vacuum hose in place. Now 90% of the ping is gone but I'm going to wait for warmer weather before fine tuning it further. The 440 has a mild cam and a 750 Eddy carb. Anyone with experience with this issue and advice please pipe up.
Joined: Sat Nov 15 2008, 08:27PM
Location: NE Pennsylvania
Posts: 428
I am not 100% sure with regard to a '68 440 but I believe that most Mopars of that era used ported vacuum for the distributor advance line instead of manifold vacuum. That would provide little to no vacuum at idle but provides the vacuum signal after the throttle is opened. You might want to try switching to ported vacuum to see if that helps.
What temperature thermostat are you using? If you currently have a 195F you might want to try a 180F to see if that helps. Some will say that this hurts efficiency but so does retarding the timing.
You could also find true TDC (Top Dead Center) on #1 cylinder to see if your balancer is actually showing 0 degrees at TDC. Sometimes they can be way off. If that happens, you could be running more advance than you realize.
Are you running an open element air cleaner? Those suck up hot underhood air which aggravates pinging. A dual snorkel closed unit with two hoses plumbed to get air from a cooler spot may help.
What fuel are you running? A '68 440 required a minumum 98 - 100 Research octane which is equivalent to at least 93 - 95 pump octane on the current R+M/2 (average of Research and Motor octane) scale that has been used on US and Canadian pumps since the mid '70s. Doesn't Sunoco still have "94 Ultra" in Canada? That is roughly equivalent to 98 - 99 Research octane of the '60's.
I would check the timing chain for slop. That is probably OK though since you mentioned a mild cam.
You could try decarbonizing the engine with Mopar combustion chamber cleaner, Seafoam or distilled water.
That's what I could think of.
Andrew S. <span class='smallblacktext'>[ Edited Sun Dec 23 2012, 08:50AM ]</span>
Thanks for the response. I have a 180 thermostat installed and run 94 octane Sunoco gas as labelled on the pumps. The air cleaner is a factory dual snorkle type. The 440 was recently rebuilt so the timing chain should be good. You are the 2nd person that has suggested the ported vacuum hook up. I always assumed that was only done starting in the mid-70's to compensate for the relatively leaner fuel mixture at idle and to reduce emissions? Can't hurt to give it a shot.
One other thing I should mention is the motor is out of 78 New yorker and is running electronic ignition from that era without the lean burn set up if that makes a difference.
Joined: Sat Nov 15 2008, 08:27PM
Location: NE Pennsylvania
Posts: 428
Nessie wrote ... One other thing I should mention is the motor is out of 78 New yorker and is running electronic ignition from that era without the lean burn set up if that makes a difference.
If the motor is out of a '78 NY then the compression ratio is 8.2:1 if memory serves. That should run on today's pump gas without a problem. The '68 engine would have had at least 10:1 from the factory - thus needing high octane. Were the heads or pistons changed to raise the compression ratio on the '78 engine? Stock '78 engines were set up to run on regular unleaded (87 R+M/2).
I wonder if the cam profile (duration/overlap/lift/lobe separation relationships, cam gear advanced or retarded, etc.) could be part of the problem. Someone else with knowledge of these things would have to chime in on that topic.
If the engine still has the stock '78 compression ratio, then I think you likely have a timing problem with either the balancer (inaccurate marks) or perhaps the timing curve in the distributor. Is the distributor a stock unit?
Comp cam XE262H-10 intake/.462 exh/470 duration @ .050 intake 218 exhaust/224. KB836 pistons. Should have mentioned CR after rebuild is now 9.1. Will try the port hook up after Christmas when I get the car out again subject to weather. Thanks Andrew.
The factory recommended timing settings are suggestions only. Every engine runs a bit differently due to wear/tear on the rings and valve guides, etc. so if you want your engine to run the best it possibly can, go buy a decent VACUUM GAUGE, as it is really indispensable in setting up your ideal ignition timing and carburetor mixture/idle settings.
First set your distributor up the way it should be: limit the mechanical advance to about 20-24 degrees, have it all in by 2200-2400 rpm, and have a vacuum advance that kicks in about 12 degrees of vacuum advance on top of that.
Hook the vacuum gauge up to the lower port (full vacuum) and fire the engine up. Advance the timing until you get the maximum vacuum reading possible with a SMOOTH idle - you'll feel it start to run worse when you've gone too far. Then retard the timing 1/2" to 1" of vacuum and lock it down. Now adjust the carb mixture and idle, then go back and check the timing using vacuum readings again. When you get a good vacuum reading with the mixture/idle set right, lock the distributor down and go for a test ride. If the engine pings, then retard the timing in 1/2'' vacuum reading increments until it stops, readjust the mixture/idle and you're done.
Joined: Fri Jan 18 2008, 10:06PM
Location: Richmond, VA
Posts: 383
I had a 1969 Monaco 440, 9:1, Edelbrock 750 cfm. It did the exact same thing. I even tried running no thermostat and it didn't help. I had it on manifold vacuum, which brought vacuum advance when I didn't need it. I never resolved the issue. I'd sure like to know the outcome with yours, since mine is long gone.
Thanks Kraut. I'll need to try to find a portable vacuum guage. The one on the console isn't convenient for this purpose. It's hard to sneak out to the car around Christmas LOL.