Hi all,

I replaced my head gasket with an MLS gasket which in turn upped my Compression Ratio from 9.25 to 9.75. Today was the first day I've really got to play with it much and I noticed under heavy load and giving her solidly, she's pinging. Doesn't ping without a good load and lots of gas and typically higher rpm ranges like 4000+.

I am pretty sure just upping to higher octane gas will resolve it but I was wondering if retarding the ignition timing a couple of degrees will resolve the ping and let me stick to the economy octane the motor used to take before the head gasket change?

 

Most hondas with 9.75 and up cr are running 91.

You might want to run a compression test to see if your head gasket is sealing.

 

Good to know. I think I discovered the issue. I just checked the ignition timing and I was advanced by 3 or 4 degrees. Got it where it should be now or at most a half a degree retarded. Will find out on tomorrows commute to work and back.

Edit addition:Still pinging but no where near as bad as when the ignition timing was advanced. Will give a 2 degree retard a try but I suspect that I will have to run at the bare minimum the 89 octane gas.

Also of note, I typo'd and my CR is supposed to be 9.73 via the zealworks calculator. Carbon buildup likely pushes that to the 9.75 though. It is an old motor that's been sucking down oil for a couple of years.

 

use premium which is like 92-94 depending where u live. has a lesser chance of igniting. you can also ADVANCE the ignition slightly but thats once you start using higher octance.

 

Straight from wikipedia, also stated by other detonation articles I found. Some in more detail that what is on wikipedia including one on cam theory...

The trick to reduce cylinder pressure is to use an adjustable cam gear and adjust your cam timing. I just don't remember off the top of my head if you advance the cam a touch or retard it a touch but it helps keep cylinder pressure lower.

And where I am at we have 87-89-91 and very far and few in between you can find a station or two that has 93. Premium is pretty much 91 here 9 out of 10 times here.

 

That worked, 2 degrees retarded ignition timing prevents the pinging/detonation with 87 octane.

Spec is 16 degrees BTDC but with the upped compression ratio and I am currently running 14 degrees BTDC on ignition timing to keep being able to use 87 octane gas.

Nice to know I can choose a little extra power or stick with economy at will. Put in premium gas and can probably go to 18 degrees BTDC and get a little more power out of it, or run 14 degrees BTDC to stick with cheap gas.



I just hope the severe pinging I had the first day didn't do any major damage. I did open her up really good and didn't notice it immediately. Will be pulling my spark plugs and inspecting them and the piston tops with a flash light tonight to see if there is any obvious signs of damage.