cam swap done... BIG PROBLEMS
Thread Starter
On The Tree
Joined: Dec 2008
Posts: 125
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From: Pittsburgh
cam swap done... BIG PROBLEMS ok so i just finished up my cam swap. this is the specs on my cam and springs:
cam: .580/.590
288/294
236/242 @ 050
114 lsa
springs: 1.290"/.885" OD
1.055/.650" ID
130 lbs @ 1.800" -valve closed, spring instralled height
320 lbs @ .600" lift (1.200")
345 @ .640" lift (1.160")
max lift- .640"
rate- 313 lbs
average coil bind @ 1.090"
higher pressures than comp 26915 springs
Now heres my problem. On first startup try we heard a loud grinding noise from the front of the motor before it started cranking right. When i got the timing cover off before the old cam came out the timing chain had some slack in it. It had the same amount when i got the new cam in. I had the dots on the crank and cam pulley aligned perfect. I have a strong feeling that the chain skipped off the teeth on the first try. Now when you crank it, it cranks fine but all it does is little pops and occasional big backfires as it cranks. It wont even fire. All i can get out of it is the popping during cranking. Now i think its just the timing chain skipped off, but my buddy thinks that my injectors are wayyyyy too small for the cam and its not even getting enough fuel to fire. HELPPPPP!
Thanks
cam: .580/.590
288/294
236/242 @ 050
114 lsa
springs: 1.290"/.885" OD
1.055/.650" ID
130 lbs @ 1.800" -valve closed, spring instralled height
320 lbs @ .600" lift (1.200")
345 @ .640" lift (1.160")
max lift- .640"
rate- 313 lbs
average coil bind @ 1.090"
higher pressures than comp 26915 springs
Now heres my problem. On first startup try we heard a loud grinding noise from the front of the motor before it started cranking right. When i got the timing cover off before the old cam came out the timing chain had some slack in it. It had the same amount when i got the new cam in. I had the dots on the crank and cam pulley aligned perfect. I have a strong feeling that the chain skipped off the teeth on the first try. Now when you crank it, it cranks fine but all it does is little pops and occasional big backfires as it cranks. It wont even fire. All i can get out of it is the popping during cranking. Now i think its just the timing chain skipped off, but my buddy thinks that my injectors are wayyyyy too small for the cam and its not even getting enough fuel to fire. HELPPPPP!
Thanks
Thread Starter
On The Tree
Joined: Dec 2008
Posts: 125
Likes: 0
From: Pittsburgh
thank god. I dont have money for injectors right now. lol
He said that the stock ones will be maxed out and still not enough for my cam.
I'm gonna try switching the coil packs first and try it and if it doesnt fire i'll tear it back down to the chain.
How do you adjust the tension on the timing chain? I dont think theres supposed to be that much slack in it..
He said that the stock ones will be maxed out and still not enough for my cam.
I'm gonna try switching the coil packs first and try it and if it doesnt fire i'll tear it back down to the chain.
How do you adjust the tension on the timing chain? I dont think theres supposed to be that much slack in it..
These motors don't have tensioners except for some of the VERY early ones. I saw a guy on the vette forums that modified a Gen IV TC damper and put on his LS1.
Some play in a stock chain is normal. I would pull the TC cover off and make sure you are dot to dot and go from there.
Edit: Here I am not too lazy today>>>> http://forums.corvetteforum.com/auto...ls1-block.html
Some play in a stock chain is normal. I would pull the TC cover off and make sure you are dot to dot and go from there.
Edit: Here I am not too lazy today>>>> http://forums.corvetteforum.com/auto...ls1-block.html
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As far as the injectors go, I just did a cam and heads.
Cam 225/229 .580/.590 114+4 LSA
My stock 28lb injectors were at 110% duty cycle. Anything over 80% duty cycle is really stressing the injectors. You might want to look into injectors soon lol
edit: I swapped out to Ford Green Top 42lb injectors
Cam 225/229 .580/.590 114+4 LSA
My stock 28lb injectors were at 110% duty cycle. Anything over 80% duty cycle is really stressing the injectors. You might want to look into injectors soon lol
edit: I swapped out to Ford Green Top 42lb injectors
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All other problems aside, your stock injectors will run WAY WAY WAY more engine than you have enough to fire it up, idle it, and even drive it around town...AND even to go full throttle at low RPM...I'll be very very very surprised if you need more injector below 4000 or even 4500 RPM...so worry about them later, troubleshoot your problem first, get the engine running, then look at your potential fuel system issues.
I'd re-check everything..the LS2 Chain is a good upgrade.
Ya that's definately crazy..lol..I switch mine all the time and I don't have any problems.
Whoever told you that kick 'em in the dick for me..
Whoever told you that kick 'em in the dick for me..
Might also double check and make sure your coil packs are on the correct sides.. Sounds silly, but the car won't fire if they're not.
TECH Regular
Joined: Jan 2008
Posts: 458
Likes: 0
From: Bellaire, TX
sound like your 180* out, pull the front of the motor back down and remove the timing cover, also remove the valve covers. make sure its still dot to dot, these timing chains on these LS motors have slack, IT'S OK, even the expensive doubble roller chains have slack.
If its not lined up dot to dot and I mean DEAD ON, then get it there. some times the crank sproket is hard to see the dot but its there. If it is DEAD ON dot to dot you my have to degree in the cam, which will mean you will need to remove the drivers head. But first make sure the cam was not install 180 out. You should have lined the dots up befor removing the old cam this way you know is it good. alot of guy have a problem of tearing it all down and pulling the old cam out with out lineing up the dots. once the cam is out they spin the motor over till the #1 piston is up and then it's a 50/50 change of it being right or 180 out.
by the way if it were just a tooth off in either direction it would still run but it would run like total ****, spit'n and spudering. But if its not running at all and popping throught the intake, it's 180* out.
Good Luck
If its not lined up dot to dot and I mean DEAD ON, then get it there. some times the crank sproket is hard to see the dot but its there. If it is DEAD ON dot to dot you my have to degree in the cam, which will mean you will need to remove the drivers head. But first make sure the cam was not install 180 out. You should have lined the dots up befor removing the old cam this way you know is it good. alot of guy have a problem of tearing it all down and pulling the old cam out with out lineing up the dots. once the cam is out they spin the motor over till the #1 piston is up and then it's a 50/50 change of it being right or 180 out.
by the way if it were just a tooth off in either direction it would still run but it would run like total ****, spit'n and spudering. But if its not running at all and popping throught the intake, it's 180* out.
Good Luck
Last edited by 1969mach1; Mar 26, 2010 at 04:37 PM.
TECH Regular
Joined: Jan 2008
Posts: 458
Likes: 0
From: Bellaire, TX
Next time you get into one of these, try something. Line 'em up dot to dot, turn the crank 360º, and see where the cam dot is. It'll be at 12:00 high just like the crank gear dot...the PCM sorts out whether it's intake or exhaust stroke every time you start the car, so it doesn't matter if you try to get 180º out, it's still going to start as long as it's not off a tooth!
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TECH Regular
Joined: Jan 2008
Posts: 458
Likes: 0
From: Bellaire, TX
Next time you get into one of these, try something. Line 'em up dot to dot, turn the crank 360º, and see where the cam dot is. It'll be at 12:00 high just like the crank gear dot...the PCM sorts out whether it's intake or exhaust stroke every time you start the car, so it doesn't matter if you try to get 180º out, it's still going to start as long as it's not off a tooth!
learn something new every day!!! 
Thanks Matt
theres something else going on, timing chains dont skip. if there was ALOT of slack, it could throw off the timing, but nothing more than a few degrees. it'd still start. run like ****? yes. another thing is, if you lined it up dot to dot, it came out the same way. if the chain had all this slack, it wouldnt have run before you swapped the cam either, the timing would have been off the same amount.
crankshaft position sensor?
crankshaft position sensor?
On The Tree
Joined: Mar 2008
Posts: 150
Likes: 0
From: Acworth, GA
Did you reinstall the camshaft retainer plate? Maybe the camshaft is floating to far forward causing the cam sensor to not read right, or your lifters are hitting 2 lobes versus 1??? Could explain the grinding sound from front of motor while cranking?? 
If you installed that cam 1 tooth off, you may have bent valves... P to V on that cam could be tight depending on how its ground. If you installed it off, it could have caused piston to valve contact.
As stated above, you REALLY need to check cam timing...
Shane
As stated above, you REALLY need to check cam timing...
Shane
trouble I bet your engine is out of time. The grinding noise you heard was the cam hitting the valves. You need to check the timing. My bet is you have cute little eyebrows on your pistons now.