what could cause 16 bent pushrods on start up after cam swap
10-18-2003, 02:09 PM
#1
what could cause 16 bent pushrods on start up after cam swap my friend just finished a cam swap on his LT1, he installed a cc305, comp r lifters, and comp magnum 1.6 rockers.
on start up he said the car ran for about 20 seconds, sputtering but not making any crazy noises, than it died. he also said before he started it he turn the motor over by hand and there was no interferance.
after the car died he pulled the valve covers and found 16 bent or broken pushrods.
what would cause this. could the rockers have been too tight. i dont think there was p-v contact because he said there were no strange noises
im really confused on what could cause 16 bent pushrods
on start up he said the car ran for about 20 seconds, sputtering but not making any crazy noises, than it died. he also said before he started it he turn the motor over by hand and there was no interferance.
after the car died he pulled the valve covers and found 16 bent or broken pushrods.
what would cause this. could the rockers have been too tight. i dont think there was p-v contact because he said there were no strange noises
im really confused on what could cause 16 bent pushrods
10-18-2003, 02:48 PM
#2
Re: what could cause 16 bent pushrods on start up after cam swap LT1s use an adjustable rocker arm. Looks like once the new lifters pumped up with oil, the preload on the lifters was too much and the valves hit the pistons. He probably has 16 bent valves now too.
10-18-2003, 03:02 PM
#4
Re: what could cause 16 bent pushrods on start up after cam swap iether they sent him the wrong cam..... or.... thats fuked up btw.... they sent the wrong rocker arms wich has happened to me before, I noticed they were incorrect before the install thankfully, did he have the new lifters soaking in oil the night before and did he do a dry rocker adjustment?
10-18-2003, 03:22 PM
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Re: what could cause 16 bent pushrods on start up after cam swap I will tell you what happened but don't get upset, he didn't check piston to valve clearance. Had he done that the problem would have slapped him in the face.
10-18-2003, 03:46 PM
#6
Re: what could cause 16 bent pushrods on start up after cam swap the cc305 is pretty small cam, there shouldnt be any piston to valve clearance issues. he didnt order it, another friend pulled it out of his car and gave it to the kid with the bent pushrods. there were no clearance problems is the previous car, so why would there be clearance problems here. he even turned the motor over by hand before he fired it up and said there was no problems there
he left the lifters oil for well over an hour before he put them in, not overnight though
ps, ive done multiple cam swaps (ls1, sbc, ford, olds). so has he. we both know what we are doing and we both know its not like spreading peanut butter on bread, but it aint rocket science. neihter of us have seen anything like this before. especially with a cam this small
he left the lifters oil for well over an hour before he put them in, not overnight though
ps, ive done multiple cam swaps (ls1, sbc, ford, olds). so has he. we both know what we are doing and we both know its not like spreading peanut butter on bread, but it aint rocket science. neihter of us have seen anything like this before. especially with a cam this small
10-18-2003, 03:56 PM
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Re: what could cause 16 bent pushrods on start up after cam swap Well, I bent the sh*t outta valves when my cam timing gear did this in my LT1 car. But all my pushrods are still straight as an arrow. 
Those look like stock pushrods, maybe he got lucky and didn't bend valves. I wish my Trick Flow chromoly pushrods had bent instead of 10 of my valves. 
This was with a Thunder XE-230/236, which is about the same size as a CC305 IIRC.
Maybe he did get lucky. Run a compression check and / or leakdown check to see if he bent valves. And make sure the timing system is lined up properly! He may be 180 degrees out.
-Andrew
Those look like stock pushrods, maybe he got lucky and didn't bend valves. I wish my Trick Flow chromoly pushrods had bent instead of 10 of my valves. This was with a Thunder XE-230/236, which is about the same size as a CC305 IIRC.Maybe he did get lucky. Run a compression check and / or leakdown check to see if he bent valves. And make sure the timing system is lined up properly! He may be 180 degrees out.
-Andrew
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10-18-2003, 04:03 PM
#8
Re: what could cause 16 bent pushrods on start up after cam swap the cc305 is 220/230 .544/.544 114 lsa (.544 is with 1.6 rockers)
ill tell him to do a comp check and see what happens.
i didnt help him install it, but when he called me and told me what happened i thought p-v contact too
hes positive its timed right, and pretty certain there was no contact because he said it sounded pretty normal when he started it, just missing sightly, but i dont know what else could have caused it
ill tell him to do a comp check and see what happens.
i didnt help him install it, but when he called me and told me what happened i thought p-v contact too
hes positive its timed right, and pretty certain there was no contact because he said it sounded pretty normal when he started it, just missing sightly, but i dont know what else could have caused it
10-18-2003, 04:12 PM
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Re: what could cause 16 bent pushrods on start up after cam swap Well, I have a friend who was positive he timed his cam install right also... Lined up the cam dot with the crank keyway.
Oops. Bent valves.
Have him triple check the cam timing. Tell him that I said not to half *** it, drop the oil pan, pull the timing cover and check it. :p
FWIW, I didn't hear anything either when my valvetrain came apart. It just stopped running (I did the cam swap - and put on a brand new double roller timing gearset, and that happened after about 3 hours of running, so I think it was a defective gear).
-Andrew
Oops.
Bent valves.Have him triple check the cam timing. Tell him that I said not to half *** it, drop the oil pan, pull the timing cover and check it. :p
FWIW, I didn't hear anything either when my valvetrain came apart. It just stopped running (I did the cam swap - and put on a brand new double roller timing gearset, and that happened after about 3 hours of running, so I think it was a defective gear).
-Andrew
10-18-2003, 04:16 PM
#11
Re: what could cause 16 bent pushrods on start up after cam swap If the cam timing was off you would think that 8 valves would be bent, either 8 intakes or 8 exhaust depending on whether the timing was improperly advanced or retarded. In this case it's pushrods not valves and it's all 16, not 8. That means what ever was done wrong was done wrong the same way on ALL 8 cylinders. You may have over preloaded all the polylocks and caused the piston to hit the valves. The pushrods are the weakest link in the chain. You better pull the heads and look at your piston crowns and take the valves out to see if any of those are bent too. You don't put much preload on "R" lifters. Just turn till the rod won't spin and then STOP and tighten the set screw. My heads are milled 0.030 and my rods didn't bend.
10-18-2003, 05:09 PM
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Re: what could cause 16 bent pushrods on start up after cam swap
the cc305 is pretty small cam, there shouldnt be any piston to valve clearance issues. he didnt order it, another friend pulled it out of his car and gave it to the kid with the bent pushrods. there were no clearance problems is the previous car, so why would there be clearance problems here.
he even turned the motor over by hand before he fired it up and said there was no problems there
left the lifters oil for well over an hour before he put them in, not overnight though
ps, ive done multiple cam swaps (ls1, sbc, ford, olds). so has he. we both know what we are doing and we both know its not like spreading peanut butter on bread, but it aint rocket science. neither of us have seen anything like this before. especially with a cam this small
Shortcut#4 + either lazyness/ignorance or both.
What I'm trying to say is he doesn't KNOW what he's doing.
Too many shortcuts. It is not rocket science, it's physics!
My apologies for flamin' but I get
when I see such damage on an engine due to ignorance or disregard of buildup protocols that are done for a reason such as preventing what happenned to those prods (& Lord knows what else)
10-18-2003, 06:05 PM
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Re: what could cause 16 bent pushrods on start up after cam swap 4thGenRetard, you need to calm the hell down. Are you a pushrod? No, so why are you so offended by this.
10-18-2003, 07:44 PM
#18
Re: what could cause 16 bent pushrods on start up after cam swap How did he adjust the rocker arms??? Like I said, this is an adjustable rocker arm/valvetrain. With no oil pressure going to the lifters, the internal piston in them depressed enough so there was no contact when he turned the engine over by hand. Once he fired it up, the lifters pressurized and took up the slack and the rocker arms were tightened down too tight, causing piston to valve contact. You don't just tighten the rockers down like on a LS1. You should have left them all loose, started the engine and then tightened each one down until it stopped clicking, then an additional 1/4 to 1/2 turn. This all assuming the cam was timed right.
10-18-2003, 07:49 PM
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Re: what could cause 16 bent pushrods on start up after cam swap
4thGenRetard, you need to calm the hell down. Are you a pushrod? No, so why are you so offended by this.
(maybe the'll do it right next time with no shortcuts).
Engines can't speak for themselves so I did it for them.
10-18-2003, 08:02 PM
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Re: what could cause 16 bent pushrods on start up after cam swap
How did he adjust the rocker arms??? Like I said, this is an adjustable rocker arm/valvetrain. With no oil pressure going to the lifters, the internal piston in them depressed enough so there was no contact when he turned the engine over by hand. Once he fired it up, the lifters pressurized and took up the slack and the rocker arms were tightened down too tight, causing piston to valve contact. You don't just tighten the rockers down like on a LS1. You should have left them all loose, started the engine and then tightened each one down until it stopped clicking, then an additional 1/4 to 1/2 turn. This all assuming the cam was timed right.
In the 'OLD' days` we used to cut tall valve covers off and use them to do rockers adjustments. diminishes oil splashes all over.
Ok, I'll help a little more.
Once your rockers are on you tighten them slowly, holding the Prods with your other hand twist them untill you cannot do so freely (but barely). You have to do so at TDC for every cylinder.( the trick is to find TDC for #1 and then follow the SBC firing sequence)by turning the motor by hand at the crank.Clockwise.
Oh and when u start the motor for the first time run it at 2000-2500 rpm for 3-4 minutes to break in the cam.
Once that is done you can idle the motor and adjust the rockers while motor running 1-2 3-4 5-6 7-8 untill ticking is barely noticeable.
And voila!