66ccode

Maybe a silly question, but how can you tell when your engine pings? I have a twin 2 1/4 system with straight through flow masters, and I cant hear anything over the exhaust.
Std timing is 6 deg BTDC, and I run Optimax, or Mobile 8000 all the time.
Its a 289, c4 with std comp, mild cam, edelbrock performer intake and Holly 465 in a 66 mustang.

66ccode

I just realized I posted that last one in the cleveland section, but I guess it doesnt really matter.

TruBlu351

Ahhhrgh, they all have 8 pots mate!

Pinging is like DNA. It's different for every vehicle (comp ratio, CC size, stroke, cam, etc etc).

Loud though your car may be, you'll know pinging when it strikes. It's more like a "rattling" sound from your engine under load or acceleration. You'll develop an ear for it so you can hear/feel the earliest onset. Very bad for motors and to be avoided at all costs.

I guess you'd have your initial timing around 10 degrees? which should be fine. As long as your car is perky off the mark and doesn't bog down, your timing is generally OK. You could advance the timing in 2* increments to see how performance changes. If it improves good, but eventually you'll run too much, causing your car to ping (rattle), then nip it back 2*.

The 98 RON fuel allows more timing, reducing the onset of pinging. If you set your timing on 98 fuel, then used normal ULP, you'd expect some pinging.

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XE Falcon
393 Tremec TKO 9"

xdclevo

Don't be fooled. Allthough you may hear it just off idle under load, you won't hear it a top revs if pinging. You can keep adding a few degrees of initial timeing, and if doesn't ping, all MAY be ok, but make sure you check the total timing, beacause if it too high, that is the pinging you won't hear untill it is too late.

RPO-083

I've seen std 351 clevos running 40 degrees initial (yep, that's past the marks on the balancer, and "no", the balancers hadn't spun) and not a sound could be heard. I don't think it is a good idea to set "by ear" personally.

TruBlu351

Good point. Especially pipes off!

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XE Falcon
393 Tremec TKO 9"

northiam

High rpm WOT pinging is much less likely due to the cylinder filling and pressures being lower as the cylinders dont have time to fill to the denonation pressure levels!

russxr67

I don,t think it would ping with 6 degrees in it. You will definately hear the death knell from the engine when she starts pinging. I ran a 302 winnie in an xr years ago and found it responded really well when i jacked the timing up to around 14 degrees. Give that a go and i think you will be suprised at how much better it goes than at 6 degrees.