What can I do when the engine is pinging ?

[coronet67]

I have built a blower engine with a friend for his ´69 Coronet.

Here are the informations about the engine:

500 cui (440 stroked), 8:1, Edelbrock Heads 88 ccm, 850 Holley with
76 primary and 84 secondary jets.
Supercharger F1 with 3,75 pulley
MSD2 coil, orange mopar ignition box, Mopar vacuum
distributor.

Engine is pinging by 2000 rpm in a high gear under full load. We removed the belt and tried it without the supercharger but the pinging was still there.


I also use a Keisler 5 speed but the clutch is
slipping.
What clutch you would recommend?Centerforce?Hays?


Thanks in forward

greetings Ja

[custom880]

You didn't mention the cam that is in the car. Was it dialed in correctly? It sounds like ignition timing to me. You also don't mention the plugs, or wires, or what grade of fuel you are using. Could be low octane.

[fox]

Look at the timing curve. Also, those look like very small jets for what you are doing. Bump the primary's to 78-80 and secondary jets to 88. When running any real boost, you should have good gas/ octane in it. BTW, race gas is good quality, better than you can get at a pump.

[gsmopar]

What total timing are you running?

[coronet67]

thanks for your fast replies,

we are running 100 octane fuel. We have setted the cam on zero. The cam was build by Scott brown for this engine combo. I have to look for the data of the camshaft. We use Bosch plugs with a heat range of 6.

[ehostler]

8:1 naturally aspirated with 100 octane should not ping. The only reason that it would is if the timing is far too advanced, the carb is too lean, and/or a massive vacuum leak.

[dave571]

Originally Posted by ehostler

The only reason that it would is if the timing is far too advanced, the carb is too lean, and/or a massive vacuum leak.

Lean carb may be a trail to follow....
750 holley is way too small for a 500 inch stroker with an air pusher.

Whats the timing set at?

Try it without the vacuum advance hooked up. Vacuum advance is for economy, and you won't get any with a 500 inch motor anyway.

[345Dart]

Dave571
I believe he has stated he has an 850 holley - which may still be not big enough for a 500in with radical cam.
coronet67
replace the orange ecu with a Mopar chrome - the orange are not known to be not very reliable and tend to give inconsistent operation. The fatten up the jets to 80-88 and see if any difference.

[coronet67]

the cam has a lift of round about .580
Do you think that the Spark plugs are the right one for this application (BOSH heat range 6) or are they probaply to cold?
What size of carburetor would you recommen?

wish you all a nice weekend

[pishta]

dont discount an 850 as a adequate blower carb, remember 850 is measured at 1.5 inches Hg. When you start force feeding a carb at More pressure (actually less pressure...more pressure drop) your ratings go out the window. 390's on stock cars? yeah, remember the pressure drop. More RPMs equate to more negative pressure under the carb, resulting to more actual CFM's. Youll really have to get an O2 sensor and a vacuum guage to determine where you are in flow. Like a hose, you can get full flow out and create a fountain that is 3 inches tall, or you can get full flow and get a guyer that looks like a toppled fire hydrant.