Engine Misfire. Gas & Exhaust Fumes in the Intake
03-10-2005, 11:38 PM
#1
Engine Misfire. Gas & Exhaust Fumes in the Intake I'm sure it's a Broken Valve Spring..
Motor is a 347ci Aluminum, Ross Pistons, Total Seal Rings, HotCam and Jessel 1.8 Rockers. Total Valve Lift = about .555. ATI Blower 13PSI + and running about 700RWHP.
Did not over rev the motor, and hardly ever take it to 6500rpms, I was cruzing down the Hywy at 70MPH, 1500 engine rpms and the engine just all of a sudden started to vibrate, bad.. I pulled over and the motor was barely able to keep at idle.. I limped it home 5 more miles and shut her down for the night.
Next day changed the plugs, looks like I have been running rich for a while but I did not do a Compression Check as yet since I didn't have a tester, however #7, #5 & #8 spark plugs were wet from fuel, just after a short 2 minute engine run before the plug change. A-Tap says the #7 Cylinder is misfireing most of the time, at different rpms, although #8 and #5 sometimes does as well which are closest to #7.. After the engine runs I see Fuel in the back of the intake when I open the TB and exhaust fumes coming out as well. That was an indication that I have a Compression Problem, but I thought perhaps one of my 50lb injectors was stuck open all the time. I switched out to my Lucas 38's and the problem is still there.. I'm sure it's a Intake Valve Spring on the #7 Cylinder but looking at the spring itself after taking off the valve cover, it looks fine. Not sure which Valve spring I'm running but the local shop that ported my heads installed them on there and said they were good up to .650 lift. I think they are Manley or maybe REV Springs. It's a dual sping and was installed 2 years and 16,000 miles ago..
My question is this.. Does this sound like a Bad Valve Spring and possibly a bent valve after it kissed the piston?
It's a long shot but any possible way I skipped a tooth on my Double Timing Cam Chain? Which would get the Cam out of timing?
Last question.. I have a friend that has New 2002+ ZO6 Valve Springs good for ???? Lift. With an older style Cam like the Hotcam with not alot of ramp rate, would the 2002 Z06 Valve Springs hold up? Remember I have the Jessel 1.8 Rockers which brings my lift to about .555 to .560.
Let me know..
Thank you!!!
Clint
Motor is a 347ci Aluminum, Ross Pistons, Total Seal Rings, HotCam and Jessel 1.8 Rockers. Total Valve Lift = about .555. ATI Blower 13PSI + and running about 700RWHP.
Did not over rev the motor, and hardly ever take it to 6500rpms, I was cruzing down the Hywy at 70MPH, 1500 engine rpms and the engine just all of a sudden started to vibrate, bad.. I pulled over and the motor was barely able to keep at idle.. I limped it home 5 more miles and shut her down for the night.
Next day changed the plugs, looks like I have been running rich for a while but I did not do a Compression Check as yet since I didn't have a tester, however #7, #5 & #8 spark plugs were wet from fuel, just after a short 2 minute engine run before the plug change. A-Tap says the #7 Cylinder is misfireing most of the time, at different rpms, although #8 and #5 sometimes does as well which are closest to #7.. After the engine runs I see Fuel in the back of the intake when I open the TB and exhaust fumes coming out as well. That was an indication that I have a Compression Problem, but I thought perhaps one of my 50lb injectors was stuck open all the time. I switched out to my Lucas 38's and the problem is still there.. I'm sure it's a Intake Valve Spring on the #7 Cylinder but looking at the spring itself after taking off the valve cover, it looks fine. Not sure which Valve spring I'm running but the local shop that ported my heads installed them on there and said they were good up to .650 lift. I think they are Manley or maybe REV Springs. It's a dual sping and was installed 2 years and 16,000 miles ago..
My question is this.. Does this sound like a Bad Valve Spring and possibly a bent valve after it kissed the piston?
It's a long shot but any possible way I skipped a tooth on my Double Timing Cam Chain? Which would get the Cam out of timing?
Last question.. I have a friend that has New 2002+ ZO6 Valve Springs good for ???? Lift. With an older style Cam like the Hotcam with not alot of ramp rate, would the 2002 Z06 Valve Springs hold up? Remember I have the Jessel 1.8 Rockers which brings my lift to about .555 to .560.
Let me know..
Thank you!!!
Clint
03-11-2005, 02:11 AM
#2
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did you pull out the pushrods on the #7 cylinder? also pull the spring out and check the rocker arm torques as well.
Swap around plug wires and ignition boxes between cylinders and you should hopefully find your problem.
Nate
Swap around plug wires and ignition boxes between cylinders and you should hopefully find your problem.
Nate
03-11-2005, 11:08 AM
#6
Oil Pressure is just fine.. My lift is not far off the Stock 2002+ ZO6 Cam. I hope these Springs will be okay, 1st off because I like the fact that GM makes them, should last a while. Also I can get a new set of these pretty cheap.
Clint
Clint
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03-11-2005, 12:17 PM
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Short of pulling the springs off and checking them individually. You could hook up a vacuum gauge to the engine and see if you can hold a steady vacuum at higher rpm's. If the needle on the gauge starts to get "wobbly" then you have a bad/weak valve spring(s) or the valve is sticking in the guide.
03-14-2005, 12:43 AM
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Bind on those springs are at 1.156"
If your installed height is exactly 1.8" then that leaves .644" of movement.
Most people want between .050" to .100" of room to spare before bind. I prefer .100" plus because it's easier on the springs.
To get this is as simple as cutting the spring pockets .040" or so and replacing the factory spring shims with thinner ones until you get the install height that you would like.
Then you just make sure you still have the pressure you need on the seat.
With the Z06 springs you'll only have around 75 lbs on the seat with a 1.85" install height. Since you run boost you probably want to consider stepping up to a comp 918 or better. The 918's are still at 130 lbs on the seat at 1.85" install height.
If your installed height is exactly 1.8" then that leaves .644" of movement.
Most people want between .050" to .100" of room to spare before bind. I prefer .100" plus because it's easier on the springs.
To get this is as simple as cutting the spring pockets .040" or so and replacing the factory spring shims with thinner ones until you get the install height that you would like.
Then you just make sure you still have the pressure you need on the seat.
With the Z06 springs you'll only have around 75 lbs on the seat with a 1.85" install height. Since you run boost you probably want to consider stepping up to a comp 918 or better. The 918's are still at 130 lbs on the seat at 1.85" install height.
03-15-2005, 01:59 PM
#12
Well.. Did a compression check on all cylinders. Last one #8 failed bad. 0 Psi.. All others ranged from 132 to 142 psi..
Bad Exhaust Spring. Good News is it did not damage the piston and the valve itself looks as if it didn't even hit the piston at all. Well due to the amount of work, I just dropped the motor lastnight K-Frame and all. Did her by myself in about 4 hours. Now I'm thinking new Cam, and Nicer Springs..
I want to get rid of this HOTCAM and go with a 114LSA Long split durration and about .590 total lift. What spring out there that handle this kind of lift that is the stock 1.25" diameter so the heads dont need to be worked on.??
Let me know.
CLint
Bad Exhaust Spring. Good News is it did not damage the piston and the valve itself looks as if it didn't even hit the piston at all. Well due to the amount of work, I just dropped the motor lastnight K-Frame and all. Did her by myself in about 4 hours. Now I'm thinking new Cam, and Nicer Springs..
I want to get rid of this HOTCAM and go with a 114LSA Long split durration and about .590 total lift. What spring out there that handle this kind of lift that is the stock 1.25" diameter so the heads dont need to be worked on.??
Let me know.
CLint
03-15-2005, 06:06 PM
#13
Clint....what springs did you have on the car? It did'nt look like you were very sure on if they were the Manleys or another brand.
If I remember correctly there are two different Manley Dual springs, one good to 600 lift and the other good to 650 lift.
Anyway, either of those two should be fine with your new cam. I run the Manley Dual good to 650 lift along with titanium retainers no problems.
Don
If I remember correctly there are two different Manley Dual springs, one good to 600 lift and the other good to 650 lift.
Anyway, either of those two should be fine with your new cam. I run the Manley Dual good to 650 lift along with titanium retainers no problems.
Don
03-15-2005, 07:02 PM
#14
Found out the springs are the Dual Ferrea Springs.. I'm probibly going to go with the Comp 918 springs. After I did a little research they seem like the best choice.. Now if I go with a major Cam then The Patriot dual springs seem to give me more ease of mind. 1 more thing..
Anyone out there know of a cam or close to these specs? with 230/240 durration .550 lift and a 114 LSA?
Clint
Anyone out there know of a cam or close to these specs? with 230/240 durration .550 lift and a 114 LSA?
Clint
03-15-2005, 10:53 PM
#15
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Originally Posted by HUGGER ORANGE SS
Anyone out there know of a cam or close to these specs? with 230/240 durration .550 lift and a 114 LSA?
Clint
Clint
I know someone that has it. But it is on a 112 LSA.
Cam sheet says it is a 226/234 554/575 112.
Man, no knocking though??? The problem you were having sounded really close to what was going on with my car a couple months back. Misfires down a bank, and wet plugs....
