How much knock is too much?
- Thread starter Aktyguy
- Start date
phoonTy
Truckless. For now.
i'm no expert, but 10-11 degrees constant is way way too much. i assume you're running it on DM? if it's 10-11 degrees for more than a few frames, then you'd better check some things out quick, and lay off boost for a while.
0 degrees is optimum, but with these trucks, that's sometimes hard to attain. from what i've read, and talked with people about, the occasional 3-4 degrees is acceptable, but as always, the lower the better.
although, using 110, it may be false knock. but i'm sure someone here will chime in with some good ol' "know how."
0 degrees is optimum, but with these trucks, that's sometimes hard to attain. from what i've read, and talked with people about, the occasional 3-4 degrees is acceptable, but as always, the lower the better.
although, using 110, it may be false knock. but i'm sure someone here will chime in with some good ol' "know how."
Jimmy
Banned
You are about to blow your motor up.(or it could be just too rich/lean)
12.something is max,and I think most ppl agree that anything under 5 is not too harmful.Don't beat on it with that much KR,do a complete tuneup,make sure the timing is at 0 degrees,and that your IC pump is working.
12.something is max,and I think most ppl agree that anything under 5 is not too harmful.Don't beat on it with that much KR,do a complete tuneup,make sure the timing is at 0 degrees,and that your IC pump is working.
phoonTy said:
12.7 is max on Stock chip. Hopefully you are not on a stock chip. Kind of depends on how much timing is in the chip. If you did a chip with 25 deg. of timing advance then 10-11 of retard wouldn't be bad. If your distributor isn't really at 0 then the engine is seeing more or less timing than in the calibration. If you have a stock truck that retards 2 deg consistently and you advance the distributor 5 degrees then you would probably see ~7 degrees of retard.
So it sort of depends on how much total timing the truck is actually seeing.
Have to look at the whole picture.
InvisiBill
Active member
92 black typhoon said:
"Knock retard" is when the ECM retards the timing to stop knock. If you can hear it, then there's more knock than the ECM can cancel out via timing retard. That's bad.
I think the cause of the knock was a problem with the cam bearings. The rear one spun and was moved forward blocking the oil passage to the lifters and the top end....pretty sure that was it.
I'm running 20 degrees of advance with the distributer at 0. I've been testing it on 28 lbs of boost and i'm sure the knock isn't real. It's too intermittent, even in the shop at just over 4000 rpm it'll pull 10 degrees for no reason. I retarded the timing via the distributer about 4 degrees and it doesn't change anything.
I changed the crank and bearings a couple weeks ago and pulled it apart today to check the bearings again and noticed the cam bearing problem.
I'm running 20 degrees of advance with the distributer at 0. I've been testing it on 28 lbs of boost and i'm sure the knock isn't real. It's too intermittent, even in the shop at just over 4000 rpm it'll pull 10 degrees for no reason. I retarded the timing via the distributer about 4 degrees and it doesn't change anything.
I changed the crank and bearings a couple weeks ago and pulled it apart today to check the bearings again and noticed the cam bearing problem.
assume from your last post you've already taken it apart. for what it's worth I have never heard a ping out of mine ever. either one. you've got too much. what kind and how big of an IC are you running? As boost goes up so does heat and heat is one of the things that will raise the knock, especially at the end of the run when the IC starts to get hot. where in the run is it knockin?
How much timing are you running at full boost? How much boost and what kind of fuel?
My intercooler is pretty big. It's a spearco core about 30" x 16" x 3". My IAT is about 80-100 degrees. No more than 100 degrees after a full run. Engine temp is about 167F.
The knock I'm seeing is right on the launch, it'll count up a few but then that's it. I've made some passes on the highway at 28 lbs of boost with 0 knock. I'm not hearing any knock, only seeing it from the knock sensor.
The problem with that spun cam bearing is that supplies oil to the lifters, with no oil they start to collapse and I'm loosing a bunch of valve lift at that point.
My intercooler is pretty big. It's a spearco core about 30" x 16" x 3". My IAT is about 80-100 degrees. No more than 100 degrees after a full run. Engine temp is about 167F.
The knock I'm seeing is right on the launch, it'll count up a few but then that's it. I've made some passes on the highway at 28 lbs of boost with 0 knock. I'm not hearing any knock, only seeing it from the knock sensor.
The problem with that spun cam bearing is that supplies oil to the lifters, with no oil they start to collapse and I'm loosing a bunch of valve lift at that point.
