Djs94stang

Has anyone out there experienced more than average detonation with their 5.0? The car is a '94 and likely has always had the problem since I got from the original owner years ago and the dealership where he had the car serviced backed the timing down to 8 degrees and he needed to use premium fuel. I find the same thing...I need to set the timing on 4 degrees using 93 octane to prevent any detonation. I am setting the timing with the spout removed and I have cleaned the restistor in the MAF. The owners manual states that 87 octane is sufficient but not for mine. I saw a post where some of you guys (and gals) are in the 12 to 14 degree range.....no way I could do that unless I used race fuel. Anybody have any ideas...thanks much.

vfast

if it has a ton of miles it might be the timing chain!

Djs94stang

I thought of that but it doesn't make sense for two reasons...it's pretty much always been such that the ignition timing needed to be set on the low side and if it were the timing chain that would just retard the cam timing...shouldn't have anything to do with detonation. It may be unique to mine but I thought possibly that someone else may have the same problem (if it is a problem). I was considering taking it to a service center and having them do one of those decarboning deals where they pump some solution through the FI system and supposedly clean the valves and heads of carbon. Everything that has been done to the car I've done myself except for warrantee work at the dealer but I don't think I can do the decarbon thing since they use a special apparatus.

brando5.0

The old style fords had a problem with the timing. I had the problem too. Even if the distributor shows correct timing, you can be off. Find TDC on #1 Cylinder. Then, mark #1 on distributor. Remove cap and look at where the rotor lines up compared to the mark. If its pointing away from #1, crank engine over again, until #1 comes up to top. Now, remove the rotor and the tin shield below that. Compare the tooth below to the stator. In one book, they say that if the stator is 1/2 tooth off, it is equal to 7 3/4* timing. If they dont line up, pull distributor and turn it a tooth or whatever is needed to make them line up. If you have to turn it far enough, you might need to use a long extension and turn the oil pump drive to make the distributor line back up. So, if you are off by 1/2 a tooth, that would make sense why you're running 6*. That would actually be about 13 1/3*. I can run that on 93 pump gas in mine.

roundman

another possibility is that the timing marks or pointer are not accurate also. the outer ring on the damper may have moved or not been installed so that TDC is actually located properly or the pointer could be off on the timing cover. as long as the engine doesn't detonate, don't worry about what the timing numbers actually are. and if you want to run 87 octane, then you will just have to lower the timing more until it doesn't detonate under a load.

Djs94stang

Ok...thanks. That makes sense. My impression was that the numbers may not be exactly correct on the balancer but that was just a guess. I never went through the trouble to check it...and now I don't have to. I'll just set the timing where it works without detonation and forget about it.