fighting valvetrain noise/math check
07-25-2010, 01:14 PM
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fighting valvetrain noise/math check Ok, I am tired of the valvetrain noise I have. It is loud enough that if you are in front of of beside the car you can hardley hear the exhaust (arh lts ory and borla) It is loud to the point that if I had a knock I dont think I would be able to hear it. I have been through this now with two differnent h/c setups on this 402. I now have afr 225s milled to 68cc and a .030 cometic head gasket. (pistons are in the hole .005) I have yella terras but will be switching back to the stock rocker setup.
I am currently running 7.4s. and with the stock rockers I get 2 1/4 turns from zero lash to 22lb ft (per Shane at TRs method) When I measure with my checker I come up with 9.25 turns back to 6.8 so that is 7.26 add .050 for preload and that puts me at 7.31. Going by Shanes post I should have like a 7.375 or a 7.350. Whith the other heads I had the same terrible noise. When Tony Mamo put this package together for me he figured that it would take 7.5s. I guess why are mine so much shorter than normal, and is my math correct? I will say that finging zero lash is kinda like finding the city of gold. I get to the point of no tic, but it is so sensative that it could be a little off one way or the other. I wish I could fit my fingers on the pushrod with the rocker on.
It doesnt seem to be holding the valves open, it runs good. I havent had it on a dyno to see what the curve looks like but I know what valve float feels like and I dont think I have that going on.
Will pushrods that are too long, but not long enough to hold the valves open be noisy?? I think it would be noisey if they were too short. I will do whatever it takes to make her quite. I almost hate driving the car the way it is.
I am currently running 7.4s. and with the stock rockers I get 2 1/4 turns from zero lash to 22lb ft (per Shane at TRs method) When I measure with my checker I come up with 9.25 turns back to 6.8 so that is 7.26 add .050 for preload and that puts me at 7.31. Going by Shanes post I should have like a 7.375 or a 7.350. Whith the other heads I had the same terrible noise. When Tony Mamo put this package together for me he figured that it would take 7.5s. I guess why are mine so much shorter than normal, and is my math correct? I will say that finging zero lash is kinda like finding the city of gold. I get to the point of no tic, but it is so sensative that it could be a little off one way or the other. I wish I could fit my fingers on the pushrod with the rocker on.
It doesnt seem to be holding the valves open, it runs good. I havent had it on a dyno to see what the curve looks like but I know what valve float feels like and I dont think I have that going on.
Will pushrods that are too long, but not long enough to hold the valves open be noisy?? I think it would be noisey if they were too short. I will do whatever it takes to make her quite. I almost hate driving the car the way it is.
07-25-2010, 01:45 PM
#4
I'm a believer of the 1 1/4-1 3/4 method!
I had the loudest valvetrain tick in my car, it'd happen when warmed up and you couldn't carry on a conversation in the car while cruising it was so loud. I had 2 full turns on mine. 7.4
I put in new rockers, scorpions full rollers, didn't help. I put in the new pushrods in the morning yesterday and drove all day yesterday, SILENCE. 1.5 turns 7.375
Correct pre-load is the key. I figure when warm, expansion caused the lifter to bleed down. After bled down, and under load, it'd take awhile for it to pump back up so it'd let the fast ramp rate coupled with the new lash gap gave it it's noise.
I had the loudest valvetrain tick in my car, it'd happen when warmed up and you couldn't carry on a conversation in the car while cruising it was so loud. I had 2 full turns on mine. 7.4
I put in new rockers, scorpions full rollers, didn't help. I put in the new pushrods in the morning yesterday and drove all day yesterday, SILENCE. 1.5 turns 7.375
Correct pre-load is the key. I figure when warm, expansion caused the lifter to bleed down. After bled down, and under load, it'd take awhile for it to pump back up so it'd let the fast ramp rate coupled with the new lash gap gave it it's noise.
Last edited by SladeX; 07-25-2010 at 05:12 PM.
07-25-2010, 02:19 PM
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Shimming it would be the wrong way to go about it. That will change the wipe pattern. I will measure again tonite just to make sure I come up with the same thing again(measured several times this morning and came up with the same thing.) SladeX that sounds reassuring. I hope my noise goes away. Warm or cold with mine it makes no difference. It is always loud. I did set the pushrod checker up at 7.350 and I got 1 1/4 turns to 22lb ft.
07-25-2010, 05:15 PM
#7
To be honest, the sound was pretty damn irritating and embarrassing when it happened. It sounded like something was broken, but it was fine if you took it all apart.
The best description I have is valves closing too quickly, like a loud clack or metal slapping. If you are suffering from the same sound, its probably incorrect pushrod length.
The best description I have is valves closing too quickly, like a loud clack or metal slapping. If you are suffering from the same sound, its probably incorrect pushrod length.
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07-25-2010, 07:03 PM
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yep same sound. The only thing I am wondering is should I go with the measurements from the pushrod checker or just use the turn method that Shane posted. The lifters are comp 850's cam is xer lobe 242/246 6xx (low 6 hunderds)
07-30-2010, 06:49 PM
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well, I put a set of 7.350s in this afternoon (that is what gave me exactyl 1 1/4 turns from zero lash.) Still noisey as hell. It is a little better, but not what I want. Should I put the 7.3s like I measured for with the checker. I am tired of this noise. I searched you tube and watched probably 25 vids of ls1 valvetrain noise on cammed cars and never heard one as bad as mine.
07-30-2010, 07:40 PM
#11
Did you check the wipe pattern? I found I needed pretty thick shims to get the YT's correct on the AFR heads. If the wipe pattern is not right, then everything else will be wrong as well. Stock rockers will be even worse. Based on my experience, the pushrods are too short leading me to believe the rockers are sitting too low and are biased to the intake side of the valve stem.
07-30-2010, 08:59 PM
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I checked the wipe pattern when I had the motor on the stand with checker springs. Everything looked good then. With the motor in I dont see a good way to check the wipe. I had the exact same noise with the ported ls6 heads and cam i had before. Nothing I do changes it at all. It is def not the normal sewing machine noise. I can live with that.
07-30-2010, 10:46 PM
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I run valvoline vr1 20w50. I have the bearings on the loose side.
No offense taken 69lt1, I have tried everything i can think of to quiet the noise. I am one of the few around here with a ls motor that is modded. The other ones I set up are queit. So I dont have much to compare to (small small town). I own a shop and work on cars everyday. So I am no stranger to what I am doing. From every other one I have heard or set up myself though, this is the loudest. I have called and talked to many "gurus" to no avail. I was just looking for something else to check, or If i did something wrong. I almost dont like driving the car it is so annoying.
No offense taken 69lt1, I have tried everything i can think of to quiet the noise. I am one of the few around here with a ls motor that is modded. The other ones I set up are queit. So I dont have much to compare to (small small town). I own a shop and work on cars everyday. So I am no stranger to what I am doing. From every other one I have heard or set up myself though, this is the loudest. I have called and talked to many "gurus" to no avail. I was just looking for something else to check, or If i did something wrong. I almost dont like driving the car it is so annoying.
07-31-2010, 11:23 AM
#16
I bet your rockers are slightly contacting your valve covers....
Its worth a look for sure. Yelle Terra sells a thicker gasket kit now which you might want to try.
They were always very close to the valve covers before.....some even hit slightly but if you had the exact same issue before and didn't run the YT's then that kind of throws away my theory.
Thought it was worth mentioning however.
1 1/4 turns of preload from zero lash is good (assuming this was measured properly)....a shorter pushrod with less preload wont make less noise....potentially more IMO
-Tony
Its worth a look for sure. Yelle Terra sells a thicker gasket kit now which you might want to try.
They were always very close to the valve covers before.....some even hit slightly but if you had the exact same issue before and didn't run the YT's then that kind of throws away my theory.
Thought it was worth mentioning however.
1 1/4 turns of preload from zero lash is good (assuming this was measured properly)....a shorter pushrod with less preload wont make less noise....potentially more IMO
-Tony
07-31-2010, 12:27 PM
#17
Tony,
Any part number on the gaskets?
rpmauto,
How much shim are you running? I had the issue that Tony identified and had to do a lot of grinding in the valve covers. I even had to remove the bosses for the coil bracket bolts such that I have to seal the coil bracket bolts now when I install them. There were marks on all the rockers that were making contact.
Any part number on the gaskets?
rpmauto,
How much shim are you running? I had the issue that Tony identified and had to do a lot of grinding in the valve covers. I even had to remove the bosses for the coil bracket bolts such that I have to seal the coil bracket bolts now when I install them. There were marks on all the rockers that were making contact.
08-01-2010, 07:45 AM
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Well, I dont think it is hitting the covers. I have the yella terras off and there are no witness marks on the rockers, the covers, or anything on the pushrods to indicate hitting the guide holes. I put the stockers on just to see and it makes the same noise, with the 7.35s a little quieter than with the 7.4s but still terrible.
I was at a friends yesterday and he has a 402 with afrs, much bigger cam ect. His is way, way quieter than mine. Actually after hearing his somthing def has to be wrong with mine. I do have quite a bit of rock to my pistons, but it doesnt sound like piston slap, and the cylinder walls look good. I am at a loss, for the moment. I have a few more things to try, if that doesnt do it I think I will pull the motor.
I was at a friends yesterday and he has a 402 with afrs, much bigger cam ect. His is way, way quieter than mine. Actually after hearing his somthing def has to be wrong with mine. I do have quite a bit of rock to my pistons, but it doesnt sound like piston slap, and the cylinder walls look good. I am at a loss, for the moment. I have a few more things to try, if that doesnt do it I think I will pull the motor.
08-01-2010, 10:08 AM
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I will have the covers back off later today, I cant believe the pushrods are hitting as there are no marks whatsoever on the rods. I will look carefully at it though