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Sorry to resurrect an older thread, but I want to come back and say thanks - especially to DR_Whigham and RedBird.
great call on the bigger injectors!
I finally picked up a set of flow matched 40# injectors for $100, got the data sheets, and swapped them in. Took a bit to learn the idle, but the engine runs so much better now. And I'm not talking full throttle, etc. I'm talking low end torque, not smelling so bad, steady idle, less detonation.
I'm getting a dyno tune tomorrow morning, and now really excited to see how it goes. I'm going to keep babying it until then.
No problem man let us know how the tuning goes. I'm almost done getting mine back to 100% after the motor swap.
I have used a few different tools. If the heads are off pretty much anything will work. If not I hear tims tool is really good and I have used similar versions of it on a sbc and it always works good. However the hands down best one is the comp tool. It does both springs at a time and you have all the time in the world to play with the retainers and locks since the tool is tightened down on a stud. Its expensive but you can always just sell it after youre done
what are you guys using to keep your lifters up when taking the cam out?
I figured I would use two pieces of bar stock and slide them through each side of the block
I used two 24" sticks of 5/16" wooden dowel from Lowes for $3
Originally Posted by '99CajunFirehawk157
Just out of curiosity what spring compressor tool were you using before you got the $90 one that caused all the grief??
I used two different lever-type compressors that were designed for small block chevy and the autozone compressor. Then I tried to make one using thread rod to duplicate the actual tool. in retrospect, getting the stock springs off wasn't the issue. it was compressing the new springs that was the problem.
OK, well, the tuning was a mixed bag to say the least. On the positive side, I'm showing 280 pounds of torque off idle, which reflects how I wanted it to run.
On the negative side, we kept having to pull timing out to keep it from pinging. I mean it was bad. At 22 degrees in the higher RPM band, still pinging. Had to put it in safe mode, so I'm in the teens on timing. Couldn't pull it past 5500
Now, for the weird part. The torque curve is incredibly flat. It rises from off idle to about 310. Stays there until 3K, when it starts rising to 340, which is the peak at 4000 rpm, and then almost has a double hump at 5K. After 5K, it falls off fast. I would say this reflects how it drives. I find I get better acceleration in the next gear up at 3500 rpm than to take it to redline.
Everything I have ever seen on these engines is that they want to peak torque around 4800 and horsepower at about 6300. So, something is dead wrong.
Going to be pulling the timing cover off to re-re-verify the timing marks, but I spun the engine 8 rotations to make damn sure the marks lined up. If the marks line up, I'll re-degree it to check the ICL. Tuner thinks the cam grind might be way off. And this is NicD, so I'm positive the tuning is not the issue. Nic even commented that it felt incredibly torque in the mid range, so he was expecting a higher number
So, my question now is - assuming the cam checks out, what else can cause severe pinging? Sparks plugs too hot? PCV letting too much oil through?
Here is the dyno sheet. Take a look at the AFR, and it's a perfect 12.6 the whole way up. You can clearly see when it starts pinging, because the graph goes from smooth to ragged. Please remember, I'm not really concerned about the number - just the behavior. Once the behavior is corrected, the number will go way up just by not being in safe mode.
OK, well, the tuning was a mixed bag to say the least. On the positive side, I'm showing 280 pounds of torque off idle, which reflects how I wanted it to run.
On the negative side, we kept having to pull timing out to keep it from pinging. I mean it was bad. At 22 degrees in the higher RPM band, still pinging. Had to put it in safe mode, so I'm in the teens on timing. Couldn't pull it past 5500
Now, for the weird part. The torque curve is incredibly flat. It rises from off idle to about 310. Stays there until 3K, when it starts rising to 340, which is the peak at 4000 rpm, and then almost has a double hump at 5K. After 5K, it falls off fast. I would say this reflects how it drives. I find I get better acceleration in the next gear up at 3500 rpm than to take it to redline.
Everything I have ever seen on these engines is that they want to peak torque around 4800 and horsepower at about 6300. So, something is dead wrong.
Going to be pulling the timing cover off to re-re-verify the timing marks, but I spun the engine 8 rotations to make damn sure the marks lined up. If the marks line up, I'll re-degree it to check the ICL. Tuner thinks the cam grind might be way off. And this is NicD, so I'm positive the tuning is not the issue. Nic even commented that it felt incredibly torque in the mid range, so he was expecting a higher number
So, my question now is - assuming the cam checks out, what else can cause severe pinging? Sparks plugs too hot? PCV letting too much oil through?
are your cam lobes assymetrical?if so,i wouldn't degree using the ICL method.go by the cam card #s at .050 lift.
as far as the pinging,could be a number of things,or something as simple as bad gas,or too much compression for the gas your running?
are your cam lobes assymetrical?if so,i wouldn't degree using the ICL method.go by the cam card #s at .050 lift.
as far as the pinging,could be a number of things,or something as simple as bad gas,or too much compression for the gas your running?
They are symmetrical - XER's. I can only get 91 octane, but I would think 10.6 is fine for 91 octane. I deliberately kept it there instead of going to 11.
They are symmetrical - XER's. I can only get 91 octane, but I would think 10.6 is fine for 91 octane. I deliberately kept it there instead of going to 11.
I could be wrong,but that might be pushing it on a hot day.especially if you happen to get some bad gas.i'm lucky we have 93 around here.but there are some gas stations I avoid.
when I degreed mine,i used the smaller wheel.checked and rechecked,finally I was satisfied I had it within a degree or 2.i see why the experts say to use a big of a wheel as you can fit,definately more accurate.
I could be wrong,but that might be pushing it on a hot day.especially if you happen to get some bad gas.i'm lucky we have 93 around here.but there are some gas stations I avoid.
when I degreed mine,i used the smaller wheel.checked and rechecked,finally I was satisfied I had it within a degree or 2.i see why the experts say to use a big of a wheel as you can fit,definately more accurate.
Thats not even close to pushing it on aluminum heads. Ls7 comes with 11:! compression and the ls2 is 10.9 while the ls3 is 10.7. The problem is elsewhere.
Darth, did you guys verify it was in fact pinging and that it just wasnt pulling timing for false knock?
Thats not even close to pushing it on aluminum heads. Ls7 comes with 11:! compression and the ls2 is 10.9 while the ls3 is 10.7. The problem is elsewhere.
Darth, did you guys verify it was in fact pinging and that it just wasnt pulling timing for false knock?
Yes, we did. We disabled the knock sensors and got a third person to listen under the hood specifically for it. it was real, and it was BAD.
Thats not even close to pushing it on aluminum heads. Ls7 comes with 11:! compression and the ls2 is 10.9 while the ls3 is 10.7. The problem is elsewhere.
Darth, did you guys verify it was in fact pinging and that it just wasnt pulling timing for false knock?
my LS2 GTO called for 93 octane,if I remember correctly.Darth said only 91 octane is available to there.not saying for sure that's his problem.but if your close to the edge,a tank of crappy gas can put you over it.
The dots look pretty well aligned at first glance on the timing set.
I used the .050 events instead of peak lift as advised, and I'm coming up with 35 a 103 degree intake centerline, not a 112 like it should be. On the XER lobe, that puts the 050 IVC at 35 degrees and the 006 IVC at 59 degrees. Now, I'm trying really hard to ignore DCR, but I checked it anyway, and it is 8.68. So, at least, I'm thinking that 35 degree IVC event explains the peak torque at lower RPM and the double hump (if not also the detonation with 91 octane). Side comment, but I don't have the duration I should have unless it's a preload issue.
On a whim, I threw the stock cam back in to measure it, and I'm getting 110-111 ICL on the stock cam which should have 119 ICL.
I highly doubt I'd have two cams both off by 9 degrees advance. So, I'm wondering if there is a way to verify the timing set. I also still need to pull the oil pump and see if the crank key is partially sheared.
I don't remember it being off when I installed it, but I could have easily measured it wrong back then (or just now). I also ran an experiment timing it off by a tooth just to see how that would affect it, and it changed the timing by 18 degrees, so I'm pretty sure that's not it. Also, this is a stock, non-adjustable timing set with only one crank keyway.
So, I think I'm getting to the dyno curve's odd behavior. Would this also cause the severe pinging I was getting as well? I'm thinking high cylinder pressures, 91 octane, and phoenix desert heat makes a plausible explanation.
Forum searches are consistently coming up with "hot plugs" and "oil mist" as top causes for detonation, so when I put it back together, it'll have a mighty mouse and a set of colder NGK's
05-29-2015, 06:29 PM
dumping any more time or money into this and just start building the 408 I was planning to start next year.