That Dreaded "PING"
Thread Starter
Team Owner
Joined: Jun 2001
Posts: 23,375
Likes: 1,066
From: Virginia USA
That Dreaded "PING"
The last couple of times I've driven my engine has a very small/slight "ping" when under WOT and under heavy load. This is not occuring all the time I just noticed twice in the last few days. I checked my timing and it is dead on from where I set it up when I installed my ZZ4. 36 degree all in by 2800rpm. I am going to drop it to 34 today to see if it goes away. I did have my car out of service for the winter and it had less that 1/4 tank when I parked here. I don't think the gas is bad becase I filled it up the day I got her back on the road (unless the crap I bought was bad) and I have filled it up a second time also. I have not looked at my plugs yet but the last time I did they look good. Any other suggestions? This is a ZZ4 with an MSD distributor and 6AL box. It never pinged before this extended downtime. What I did during the downtime was pull the trans, replace the pilot shaft bushing and reinstall the trans. I do have Lars tune-up paper, thats what I used to set it up the first time.
Thanks
John
Thanks
John
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Did you try unhooking the vac adv? Assuming you bought the MSD dist with vac adv. I ended up buy a Crane adj can and modifying it to fit the MSD unit but you could probably make a stop to limit the stock vac adv travel, baslicaly what the stop does is increases the starting point of the vac adv so it has less travel thus adds less adv, you have to re-adj the timing because by moving the vac adv you add base timing. I lost the limiter tab that came with the Crane unit so made one out of sheet metal.
Here are the limiter tab instructions
http://cranecams.com/pdf/254g.pdf
Here are the limiter tab instructions
http://cranecams.com/pdf/254g.pdf
Thread Starter
Team Owner
Joined: Jun 2001
Posts: 23,375
Likes: 1,066
From: Virginia USA
Fevre
Yes and no (kinda) I am not using manifold vac for the vac advance so I only have the vac advance at part throttle cruising. I have no vac advance at Idle or WOT. My base timing is 12 degrees and all in timing is 36 by 2800. I'll probally dial it down 2 degrees today to see what happens.
Yes and no (kinda) I am not using manifold vac for the vac advance so I only have the vac advance at part throttle cruising. I have no vac advance at Idle or WOT. My base timing is 12 degrees and all in timing is 36 by 2800. I'll probally dial it down 2 degrees today to see what happens.
Melting Slicks
Joined: Dec 2005
Posts: 2,441
Likes: 0
Engines accumulate carbon deposits over time that can raise the compression; they also can create hot spots in the combustion chamber. If you drive your car mildly floor it a few times, this will help clear out the carbon.
Last edited by shafrs3; Apr 2, 2006 at 08:06 PM.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Lean?
If your pinging w/o vac adv and the car ran fine before the transwork i think maybe the carb jets are a little gummed up and running lean. Did you dump the fuel out'a the carb before the maitenance down time? Mostlikely the fuel in carb bowls dried up and left some gum deposites near the jet holes or inside feed tubes/passegaes.
What the heck, try a can of carb cleaner/fuel treatment. Seafoam?
Good luck. cardo0
What the heck, try a can of carb cleaner/fuel treatment. Seafoam?
Good luck. cardo0
Drifting
Joined: Jul 1999
Posts: 1,542
Likes: 43
From: Plano TX
My ZZ4 pings but my rochester is on the lean side. As a temp solution and but on a vacumm advance with less advance which sure the problem.
The real cure is a richer mixture at part and full throttle.
Find a dyno and run the car to see the mixture across the run.
The real cure is a richer mixture at part and full throttle.
Find a dyno and run the car to see the mixture across the run.
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