Haven't really found much in the search so thought I'd ask.

Those of you with 355's and flat tops - what plugs are you using? I've been chasing down an elusive ping for a couple of weeks now.
I'm running R45TS on 92 octane with ping.
I'm also all the way back down to completely stock timing tables.

 

Have you tried blocking off your EGR and putting a fuel filter on your PCV to keep the oil out?
What kind of shape are your valve guide & seals in? Any smoke?

The next thing is to carefully inspect EVERY spark plug as it comes out of the engine and look for symptoms of oil, detonation, and heat.

Oil getting into the chambers, hot spots around the chamber, or too much heat retained in the plug can cause ping assuming your timing is not too far advanced.
Clogged or malfunctioning injectors can also cause ping.

If you see signs of detonation on many cylinders then maybe try a cooler plug. If you see signs of detonation or heat on just a few, then check your fuel injectors for flow rate.

Are you positive it's definately ping and not a rattle or exhaust leak?

 

Haven't tried the EGR deal yet. I'll check it for proper operation first.
No filter on the PCV. Just stock setup with new hose.
The heads should be in perfect order. They are rebuilt with ~2500 miles on them. No smoke of any kind on startup or under full throttle.
The injectors should be in good order. They are Accel 24lb. They came with a flow rate sheet. Matched well. They also have about 2500 miles.

I do have an exhaust leak and a rattle but this is definitely not either. I'll fix those this week too just in case.

If I end up going with a cooler plug, what do you suggest?

 

My preference in plugs is Autolite. The #24 is a cooler plug then stock (#26).

If the EGR is active in the ECM and dead on the engine ping will occur. ECM adds timing when the EGR is activated.

A de-screened MAF will also cause the engine to run lean. As it throws the calibration off.

RBob.

 

Turns out the EGR solenoid is testing bad. I'll replace that and see what happens.
I'll post an update.

 

I use those same ac delcos, never had a problem n not a noticable difference with autolites. Cept for the price

 

Well I tested the EGR solenoid wrong. Used the wrong nipple so it's not bad.
This problem is driving me up the wall.
Maybe I should shut off the EGR in the computer and see what happens.

 

Try R44TS or 43's

 

Would 43's be a little too cold?

 

I'm with RBob on this one. Use the autolite #24's and make sure your gap is correct.

 

News on the colder plugs.....I now have more ping. I guess that wasn't the problem. I'll be going back to the hotter plugs.
As I was removing the plugs I numbered them. I noticed that several had a redish tint on the ceramic around the tip. Number 8 was the worst. Could that just be additives in the gas or is that indicative of a problem?

btw - rbob, my maf is stock, no mods done to it.

 

By your sig I'd venture that this is on the '88? I am not sure which spark tables you are using but the ARAP code is too aggressive in this area.

When you say an elusive ping in what way? I've been tuning an '85 Camaro engine that was swapped from the 4bbl to a TBI. Talk about ping (87 octane), I am running very little timing. Even at light cruise doesn't want more then 28-32°.

RBob.

 

Correct. This is the 88. I need to update that part of the sig. I removed the ARAP code and replaced it with the APYU which from what I understand is a stock 89 code. The timing is much more conservative in it.
Think it's possible that the Vortec cam that I put in needs different timing? I wouldn't think so. It's just slightly smaller than an L98 cam.
By elusive ping I mean no matter what i've done it always remains. It was actually detonating with ARAP although not at first. It pinged with AUJP and still with APYU. I found that I had swapped the fan switch connector with the knock sensor's when I installed the engine and fixed that so at least I'm now getting my retard.
I've completely stopped and even reversed a lot of the prom burning I've done to this car until I can get this fixed.