Greg, Wish I could take credit for that good info but that was David Not Davis. as for the issue at hand... I would want to know what the static compression ratio is and what was done to the heads. if running hi compression you need to polish the snot outta the combustion chambers and make sure there are no sharp edges or any small protrutions. Sometimes it is the electrode on the plug. maby go with a shorter plug if you have a long one. My aluminum headed 401 has just 10.39 to 1 and I get detonation if I run it hard and shut it off right away. I have to let the engine run a bit to cool off before shutting it down. I am running 93 octane and 37 degrees advance. Even on the dyno after it was warmed up and made a hard pull then shut off it would desiel. I am sure your engine had detonation on the dyno you just didn't notice. It is a pretty good load put on the engine by the dyno. That is how they figure out how much HP it makes. Davis Greg Taylor <amundaza@xxxxxxxxx> wrote: In response to Davis' running too hot comment, you could also try switching from standard coolant to Evan's Waterless Coolant. It's pricey, but does an excellent job at cooling things down, since it stays LIQUID against the hot areas of the cylinder head around the combustion chamber. It also runs at ZERO pressure in the cooling system, unlike the typical 14-16 lbs of standard antifreeze. Read up on it at : http://www.evanscooling.com/index2.html http://www.evanscooling.com/main25.htm http://www.restorationstuff.com/What_s_New/Light%20Bulbs/Antifreeze.htm BTW, I remember reading a post on the Evans NPG+ a few years back about a guy with a Dodge Dakota who ran the coolant, along with a higher temp thermostat (215 I think) and he picked up 3 MPGs on the truck. Sincerely, Greg Taylor :) <>< And the testimony is this, that God has given us eternal life, and this life is in His Son. He who has the Son has the life; he who does not have the Son of God does not have the life. - 1 John 5:11-12 --- On Tue, 6/24/08, David Crooks wrote: From: David Crooks Subject: Re: [Amc-list] Detonation To: amc-list@xxxxxxxxxxxx Date: Tuesday, June 24, 2008, 9:11 PM Other things that are sometimes helpful to try are: Switch to a colder spark plug Jet for a richer mixture. And of course, back off the advance. Detonation usually means you're running to hot, you need to figure out some way of cooling things off a bit.... Dave _______________________________________________ Amc-list mailing list Amc-list@xxxxxxxxxxxx http://splatter.wps.com/cgi-bin/mailman/listinfo/amc-list -------------- next part -------------- An HTML attachment was scrubbed... URL: http://splatter.wps.com/pipermail/amc-list/attachments/20080625/3846cd72/attachment.htm _______________________________________________ Amc-list mailing list Amc-list@xxxxxxxxxxxx http://splatter.wps.com/cgi-bin/mailman/listinfo/amc-list -------------- next part -------------- An HTML attachment was scrubbed... URL: http://splatter.wps.com/pipermail/amc-list/attachments/20080625/75b129ed/attachment.htm _______________________________________________ Amc-list mailing list Amc-list@xxxxxxxxxxxx http://splatter.wps.com/cgi-bin/mailman/listinfo/amc-list