Time for a cam swap, opinions welcome

[go_go_gadget88]

Originally Posted by zz430camaro

I have to give you credit for keeping so cool.

Thanks. I can assure you my thoughts are currently consumed by this, but it is what it is. If something is mechanically wrong, it is most likely my fault, so no point getting worked up over it.

I would be a lot more upset, but the car still runs pretty good, so there's that. I will see if TSP has any input before I proceed.


I did do some looking into cam being off. It sounds like it's possible for cam gear to be off a tooth and still run. Someone on LS1 tech had theirs off one and it sounds like theirs was having same issues I am. Down on power,not revving out, more torque than expected.

Hope I don't have to tear back into it

[zz430camaro]

I am not sure you could be a tooth off without having contact with the pistons but its possible. If it was you would have either unusally high or low cranking cylinder pressure. You sould be sitting at around 191 psi cranking pressure. I did a simulation using Performance Trends Engine Analyzer and your situation looked more like advancing the cam by a tooth and the cylinder pressure went to 230 psi. Retarding the cam dropped it to 146 psi. Might not be a bad idea to check it really quick.

[zz430camaro]

I am not sure you could be a tooth off without having contact with the pistons but its possible. If it was you would have either unusally high or low cranking cylinder pressure. You sould be sitting at around 191 psi cranking pressure. I did a simulation using Performance Trends Engine Analyzer and your situation looked more like advancing the cam by a tooth and the cylinder pressure went to 230 psi. Retarding the cam dropped it to 146 psi. Might not be a bad idea to check it really quick.

Advanced situaton is the green and dark blue lines (other is normal install, retarted situation not on this graph), you dont get the wavy action but you get the drop in HP and the torque starts to drop off bad at 5500. This is crankshaft HP and Torque. Not saying this is it but intersting analysis and the cylinder pressure would tell you this if its even mechanically possible.

[frankwjr]

Originally Posted by zz430camaro

I am not sure you could be a tooth off without having contact with the pistons but its possible. If it was you would have either unusally high or low cranking cylinder pressure. You sould be sitting at around 191 psi cranking pressure. I did a simulation using Performance Trends Engine Analyzer and your situation looked more like advancing the cam by a tooth and the cylinder pressure went to 230 psi. Retarding the cam dropped it to 146 psi. Might not be a bad idea to check it really quick.

lol...thought I was the only one who had that program! you got ver 3.4?

[zz430camaro]

Originally Posted by frankwjr

lol...thought I was the only one who had that program! you got ver 3.4?

Yep 3.4 now! I love it. Had it for years. The LS3 model I have works well, I checked it against real dyno graphs and it models things pretty darn good.

[go_go_gadget88]

I so I just need a compression gauge to check? Just hook it up to plug hole and crank it over and see if it's high or low? Guess that's an easy test. Just need to get a gauge.

I wouldn't have any idea if it can even be off without major issues. I had no contact problems binding it when I was turning it over by hand. And no issues sounding like valves kissing the piston when I fired it up. So if this is the culprit, I hope nothing has been harmed.

Ironically when I was setting the timing gear and marks I remember lining up the dots and wondering how you could mess that up. So I really wouldn't think that was it, but early signs kinda point there

[zz430camaro]

Originally Posted by go_go_gadget88

I so I just need a compression gauge to check? Just hook it up to plug hole and crank it over and see if it's high or low? Guess that's an easy test. Just need to get a gauge.

I wouldn't have any idea if it can even be off without major issues. I had no contact problems binding it when I was turning it over by hand. And no issues sounding like valves kissing the piston when I fired it up. So if this is the culprit, I hope nothing has been harmed.

Ironically when I was setting the timing gear and marks I remember lining up the dots and wondering how you could mess that up. So I really wouldn't think that was it, but early signs kinda point there

Ya, I dont think you are off (andvancing the cam reduces piston to valve clearance so I think it would hit) but a compression test would tell you if there was some kind of unusal pressure from the norm. You would need a compresion gauge and put it in a plug hole. You need to disconnect the ignition coil main harness so the engine does not start, then just crank it over and read the gauge. Even if one cylinder reads good, It would not be a bad idea to get readings for every cylinder so you know what they are. Kind of like going to the doctor and getting a check-up, healthy cylinder pressure tells you valves are closing at the correct time and they are sealed when closed.

[go_go_gadget88]

Originally Posted by zz430camaro

Ya, I dont think you are off but a compression test would tell you if there was some kind of unusal pressure from the norm. You would need a compresion gauge and put it in a plug hole. You need to disconnect the ignition coil harness so the engine does not start, then just crank it over and read read the gauge. Even if one cylinder reads good, It would not be a bad idea to get readings for every cylinder so you know what they are.

I don't have a whole lot of other theories at this point to guess on unfortunately. Unless TSP has a miracle solution I'm kind of just guessing for now.

And Frank's trick of holding the throttle to not start the car would probably come in handy here

[zz430camaro]

Originally Posted by go_go_gadget88

I don't have a whole lot of other theories at this point to guess on unfortunately. Unless TSP has a miracle solution I'm kind of just guessing for now.

And Frank's trick of holding the throttle to not start the car would probably come in handy here

Ya, process of elimination. Hey a compression test is always good to do after major engine work, gives you some insight into the engine health.

[13SSCamaro]

Compression test is a cheap and easy to do. You might be able to rent one from a local parts store as well. They are cheap at sears too if you want to buy one. That will give you instant results telling you if you are off at all. Sucks your gonna have to get it retuned no matter what you do, hopefully they will cut the retune price in half like a lot of tuners do.

[go_go_gadget88]

I live in BFE, so not a lot of stores to snag one. We do have a local auto store that possibly would. I may hit my dad up tomorrow, I think he may have one.

It's at least SOMETHING to try anyhow. And will message TSP. They may say there's no way I could have had it off any without ptv issues.

I'm sure my tuner would work with me. I just feel bad I may have wasted a bunch of his time if I discover an issue like this that would throw the tune way off.

[go_go_gadget88]

I appreciate all you guys chiming in with ideas/suggestions/opinions. Thank you!

[Bretts]

not a maf sensor signal ? just a guess at cheap stuff still in play

[Sturgill_SS]

Did you changes the springs at all? Make sure the valves were placed exactly where they came out of! I took my heads into a shop and got a compression test done after replacing the springs before putting the heads back on.