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noisy/loud valve train


A_Rescue

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Not my monte but my 95 454 truck rebuild i am close to completing and the valve train is way to loud.  Replaced the entire set of lifters today put a 1/2 turn past zero in them and the same noisy clacking valve train.  This is a comp cams roller conversion kit for the 95 GMC and the only difference is the edelbrock 60499 head vs. the stock heads.  

 

This is driving me nuts, what am I doing/did wrong?  any help is appreciated

 

 

 

1995 gmc 7.4 liter rebuild. 

Edelbrock 60499 heads

Comp cam hydraulic roller cam p/n 11-423-8

Comp cam hydraulic roller lifters p/n 854-16

Cam valve springs P/N 924-16

Cams retrofit pushrods P/N 7815-16

Comp cam retainers P/N 7411-16

Comp cam roller timing chain P/N 2110

Flat top pistons, 30/1000 over, edelbrock MPFI

 

john

 

 

 

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I personally would start over with this procedure.  Remove all spark plugs, belts and etc.  Remove valve covers, install crank tool to crankshaft nut, and re-do the lash on the rockers.  Get it to TDC and cold lash them in.  Use your fingers to spin the push rods until you fell resistance and then a 1/4 turn or so based on your abilitiy to spin the push rod with your fingers.  Do this on all 8 cylinders rotating in cycle. 

 

ps. sorry I just spilled water on my board so I hand to keep it short and sweet.  ugh - Dave

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my falcon i built 20 years ago had the same issue on a fresh build...  i was told it was because i didnt prime the lifters properly before setting the lash... i was not sure if that is true so i changed cam and lifters instead of chancing damage to anything

 

the most accurate way to set zero lash is to go up and down rather than spinning the pushrod....... strong fingers, different diameter pushrods, spring rate for the lifter and valve springs will throw off the spin method..

 

then do your half or 1/4 turn depending on application

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Thanks guys

 

I have tried zero, a 1/4, a half, and 3/4ths of a turn on all of them multiple times with the same or worse results.  Then bought a complete new set of roller lifters because I couldn't hear exactly which one was bad and I don't want to keep tearing the intake off.  Installed them at a 1/2 turn and same clacking. 

 

The rod height is correct if the rocker roller is in the middle of the stem....?

 

 

I'll start again at a 1/4 past zero lash.   

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yes we are oiling Steve we are swimming in it, 60 psi cold oil pressure, melling high volume oil pump.... also new

i got to ask....... you are running roller lifters now..... did you install a roller cam?

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Just my 2cents. I'm guessing Hydraulic roller lifters, right? If they are solid You should have a spec. card to go by from Comp.cams. If it's a solid cam lifter should be like .016/.018 lash on the rocker arm. Man I hope you don't have bent pushrods!  Sam ,(bones) on this site could help you out with this, he's done some of these too.

Jim

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when I replaced the lifters Friday with new ones, I inspected the rods, cam, and everything I could see.  I am not going to get back to it until later this week.  I'm gonna go with zero lift at first and go a 1/4 turn each time after and see where they are happy...if they get happy.  I will pull the coil lead and make sure we are oiling out of the pushrods.   Ill make sure the pushrod length is good by insuring the rocker roller is centered on the valve stem.  Ill check the valve height and depth....

 

This has been going on for a while and comp cams tech help has not been very helpful...   lots of complaints on the summit and the comp website for these lifters.  good thing it was only 100 degrees Friday....

'thanks guys

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  • 2 weeks later...

OK... got back into the valve train issue today....   checked rocker geometry and the pushrod length is spot on.   then checked seated spring pressures and saw 130 to 170 with most about 150 lbs.  Comp wants 1.9 inch installed height at 120 lbs.  a little heavy on seat pressure but that should help the steep rate of rise on the roller cam.  valve is showing roller contact in center of  valve stem.  pushrods straight and correct sizes....   reset all lifters to a 1/4 turn past 0 lash and I will fire it up tomorrow.  The disappointment in NOT finding something wrong that is making this valve train scream is getting to me...

 

back at it tomorrow and if its loud again i'm going to live with it...   

 

I advise staying away from this kit from Comp....  kit is for a roller cam conversion designed specifically for the BBC Gen IV and Gen V... irritating to keep taking this thing apart...  

 

OK enough whining...

 

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=441&sb=0

post-24188-0-58531000-1534475180_thumb.jpg

post-24188-0-20631800-1534475235_thumb.jpg

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hmmm..... you sure its not those rockers? 

 I ran a set of comp cam roller tip rockers on a 350 that looked identical to those... they always had a "click" sound to them as if the roller was tapping against its shaft.. like there was slack.

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I am looking at a new set of roller rockers with ball bearing trunions.  That will free up 20 or so horseys and they wont care if I change the cam or lifters...  lots of options...   its only money... Thanks Steve, i'll record the valve train audio tomorrow when I fire it up...  two simultaneous projects....

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Well folks I did what i could, that truck is just going to sound like a rock tumbler.   Thanks for all the feedback and especially the feedback from others who have used this comp cams set up too...   I'll borrow what was said here... ill say they are solid lifters....hehehehe  

 

on a good note...On my Monte... I put the hellwig sway bar on (lots of stuff to change from a drag racer to a street car) and took it out for a drive today.  wow....  gotta love a well built big block....

 

thanks for the support guys!!!

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My 454 is a little noisy with the retro fit roller lifters and the roller tip rockers, but not too bad. I'll be following this to hear how you do with the roller rockers.

 

Dan

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ill share the rockers chosen and the results when i pry my wallet open... Im doing a restore on a 71 monte ss and there seems to be a conflict between what I make and what i am spending right now....   HEHEHE

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