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Discussion Starter #1
I installed my 280H Comp cam with My Vortec heads, adjusted the valves exactly like Comp said to & now I think I have 5 bent valves. I turned the motor until the exhaust valve was just opening, turned the intake to zero lash & gave it 1/2 turn. Then turn the engine until the intake is half way closed & set the exhaust. I buttoned up the engine & cranked it with no fire. I checked all the cylinders & suddenly 1,3,5,7 & 2 all have no compression. I backed off all the rockers so the valves are all closed & pressured up each cylinder with air & they leak out the exhaust. How could I have bent those valves? Wouldnt they have hit when turning the engine by hand to adjust them? I have flat 4 valve relief pistons & I would think I would have to over tighten the rockers sooo much to even get close. I did have compression while adjusting the valves with the intake off, it had to happen while cranking the motor. Any ideas??
Thanks
 

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Bent valves

It could be a couple of differant things,sorry but you need to go ahead and pull the heads and then look at the damage.This should help us find out what went wrong.
Mike
 

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Discussion Starter #3
Heads are coming off this weekend, right now I'm too depressed to do it but I know it has to be done...thanks.
 

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just a thought but did u make sure your timing chain is properly installed......
I dont know why only 1, 3, 5, 7 and 2 are bent but it would be something to check too. Good luck!!:(
 

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Before you take the heads off, you may be able to take a soft faced hammer and tap the end of the valve stem. This may give you and indication if the valve is just stuck open or bent. I think a good operating valve should pop of its seat then return.
 

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This is not the proper way to adjust valves, If you have factory rockers and nuts, run the nut down till you have 4 threads showing above the nut. This will get you very close.. i always do this on startup and after the engine has run a few minutes to pump the lifters up then I adjust the valves.. T

The best way is to put the engine on TDC compression stroke on #1, then adjust #1 exh and int. after you do #1 you can turn the engine 90 degrees and follow the firing order..

Mitch

62bandwagon said:
I installed my 280H Comp cam with My Vortec heads, adjusted the valves exactly like Comp said to & now I think I have 5 bent valves. I turned the motor until the exhaust valve was just opening, turned the intake to zero lash & gave it 1/2 turn. Then turn the engine until the intake is half way closed & set the exhaust. I buttoned up the engine & cranked it with no fire. I checked all the cylinders & suddenly 1,3,5,7 & 2 all have no compression. I backed off all the rockers so the valves are all closed & pressured up each cylinder with air & they leak out the exhaust. How could I have bent those valves? Wouldnt they have hit when turning the engine by hand to adjust them? I have flat 4 valve relief pistons & I would think I would have to over tighten the rockers sooo much to even get close. I did have compression while adjusting the valves with the intake off, it had to happen while cranking the motor. Any ideas??
Thanks
 

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If you have bent valves your rocker arms should now have clearance. I would do a leak down test before pulling the heads. I would also remove all of the rocker arms and check the valve stem height in comparison to all of the other valve heights. I have also seen where valves get tightened down too much. You might think that you were at zero lash but in fact you might have bottomed out the lifter. Depends if the lifter was pumped up at the time of valve adjust.
 

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Discussion Starter #8
I swear this isnt the first engine I have put together...honest. Anyway, here is my dumbazz reason for all the problems. I had installed this cam in with the engine in the car, I had a Cloyes timing set with 3 keyways. I always use the factory setting when I install them & since I didnt need to pull the crank gear I knew that I had it on the correct keyslot. I turned the crank until I saw the first marker & went on my way forgetting that there is a marker for each keyway...this explains a lot. I have been burning the candle at both ends & got in a hurry & now(after pulling the heads) I have some nice new bent valves & pushrods to go along with them. I just new that the timing set couldnt be the problem because I lined up the marks...so much for that. Thanks for all the input guys!
 

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valves

Marks on your pistons too I bet,hope they didn't ruin them.
Mike
 

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I suggest you check the piston to valve clearance. If you would have done that you would have found your problem before you bent the valves. JMHO, RM
 

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Discussion Starter #11
The only reason piston to valve clearance was an issue was my screw up on the timing marker....a .480 lift with a 4 valve relief flattop in a SBC shouldnt have any clearance issues if the cam gear is installed right...again... totally my bad.
 

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I am assuming you have already had your valve guides machined on your Vortec heads or that you bought the ones already prepped for the .520 lift cams. If not, while you have those heads off, you need to have the guides cut down or you will have problems. Also the stock springs will not support that cam, so again, hopefully you have the prepped heads.

Been there done that, had to do it over too.
 

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Discussion Starter #13
Thanks for the heads up(no pun intended)..I have RHS Vortec heads that have already been machined for the higher lift, guide plates & screw in studs. The springs are fit to the cam also..thanks again.

Andy
 
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