Comp Cams Trunion upgrade potential problem
Speedtigger your car is a total cumshot and this prob needs to go away
right quick. If you know that 0.001 crush fit is right and I would bet it is
since press fit wrist pins are 1 to 1.5 interference, you should take the
rockers in question to a local machine shop and have them honed like a pin
fit on a rod bushing or piston would be done...I know you shouldn't have to
do this however is sounds like a manufacturing issue and clearly Comp has
your coin so some phone tech could care less........Good luck man
right quick. If you know that 0.001 crush fit is right and I would bet it is
since press fit wrist pins are 1 to 1.5 interference, you should take the
rockers in question to a local machine shop and have them honed like a pin
fit on a rod bushing or piston would be done...I know you shouldn't have to
do this however is sounds like a manufacturing issue and clearly Comp has
your coin so some phone tech could care less........Good luck man
I'm very curious to see what they say to you. I've got a brand new trunnion kit here, and a couple sets of stock rockers too...and I thoroughly intend to measure every rocker when the stock stuff comes out, and hone any if necessary before re-assembly with the comp hardware.
I like a stable valvetrain...a bump in the rocker motion doesn't sound so conducive to stability...or longevity.
I like a stable valvetrain...a bump in the rocker motion doesn't sound so conducive to stability...or longevity.
During the week I installed the Comp Cams trunion upgrade on my factory LQ9 rocker arms. What I found was that 9 of the rocker trunion installs were great. They were silky smooth and easy to rotate. However, the other 7 were varying degrees of stiff and catchy.
When the first unit came out stiff, I assumed that perhaps I did not get the bearing in straight or there may have been a burr in the bore that I did not detect. However, after taking great care and still getting several more poor results I realized there was something else causing the problem.
What I found was that there was a problem with the factory rocker bearing bore. I knew that it was either deformed or undersized. The reason this was not a problem with the factory trunion setup is because they have much more bearing clearances than the Comp Cams set up. So, this increase in crush on the bearing race is not an issue. But, because I do not have a dial bore gauge that small in diameter, I had not way to know which was the problem or to verify the measurements with enough accuracy.
While not exactly the ideal scenario without the proper dial bore gauge to measure the progress, I decided to lightly hone the rocker's bearing bores and try it again. After the first try, the bearing was much looser and smoother, but still not right. So, I honed a little more until the bearings were free and smooth.
Once I realized this was the solution, I honed the remaining 6 rockers. Now I have a full set of upgraded rockers with glass smooth bearings.
I do find it hard to believe that I am the only one to experience this problem. The engine that I removed the rockers from is a low mile engine in excellent condition. Are other people just running them not realizing they are supposed to be silky smooth and free? But, I have not found a single other post on the net of people complaining about this problem.
Anyhoo, I just wanted to share my experience in case any others run into this problem.
When the first unit came out stiff, I assumed that perhaps I did not get the bearing in straight or there may have been a burr in the bore that I did not detect. However, after taking great care and still getting several more poor results I realized there was something else causing the problem.
What I found was that there was a problem with the factory rocker bearing bore. I knew that it was either deformed or undersized. The reason this was not a problem with the factory trunion setup is because they have much more bearing clearances than the Comp Cams set up. So, this increase in crush on the bearing race is not an issue. But, because I do not have a dial bore gauge that small in diameter, I had not way to know which was the problem or to verify the measurements with enough accuracy.
While not exactly the ideal scenario without the proper dial bore gauge to measure the progress, I decided to lightly hone the rocker's bearing bores and try it again. After the first try, the bearing was much looser and smoother, but still not right. So, I honed a little more until the bearings were free and smooth.
Once I realized this was the solution, I honed the remaining 6 rockers. Now I have a full set of upgraded rockers with glass smooth bearings.
I do find it hard to believe that I am the only one to experience this problem. The engine that I removed the rockers from is a low mile engine in excellent condition. Are other people just running them not realizing they are supposed to be silky smooth and free? But, I have not found a single other post on the net of people complaining about this problem.
Anyhoo, I just wanted to share my experience in case any others run into this problem.
Speedtigger your car is a total cumshot and this prob needs to go away
right quick. If you know that 0.001 crush fit is right and I would bet it is
since press fit wrist pins are 1 to 1.5 interference, you should take the
rockers in question to a local machine shop and have them honed like a pin
fit on a rod bushing or piston would be done...I know you shouldn't have to
do this however is sounds like a manufacturing issue and clearly Comp has
your coin so some phone tech could care less........Good luck man
right quick. If you know that 0.001 crush fit is right and I would bet it is
since press fit wrist pins are 1 to 1.5 interference, you should take the
rockers in question to a local machine shop and have them honed like a pin
fit on a rod bushing or piston would be done...I know you shouldn't have to
do this however is sounds like a manufacturing issue and clearly Comp has
your coin so some phone tech could care less........Good luck man
Because of the time it would take for me to drive 25 miles to this machine shop and the expense it would incur, I am considering just getting a set already done from Texas Speed or Harland Sharp.
Either way, I would really like to get to the bottom of this for 2 reasons. 1. I am curious as to why the results vary. 2. The knowledge will be a good contribution to the LS community.
I spoke to Scott at Comp Cams today. The reason they do not have engineering specs is because the rocker kits are outsourced. He did just get a shipment in today, so he measured them for me.
As you may recall from a previous post in this thread, mine measured:
trunions bearing surface diameter .6255"
bearning outer shells diameter .8145"
Scott measured a unit from the latest shipment and they measured:
trunions bearing surface diameter .623"
bearning outer shells diameter .813"
I was shocked. .0025" diameter difference is huge on a bearing of this diameter. As we discussed this further, Scott told me that he was using dial calipers. I told him I had no confidence in measuring clearances this small with dial calipers, but he said he did not have a micrometer available to him.
Scott also told me that it is not uncommon for them to hone the rocker housing when they are installing bearings if they get one that is not smooth. So, there is proof positive for all you guys who thought it was just you. It's not.
So, I will be boxing my trunion upgrade kit to send to Comp Cams for inspection and possible replacement.
I will keep you posted as we learn more.
As you may recall from a previous post in this thread, mine measured:
trunions bearing surface diameter .6255"
bearning outer shells diameter .8145"
Scott measured a unit from the latest shipment and they measured:
trunions bearing surface diameter .623"
bearning outer shells diameter .813"
I was shocked. .0025" diameter difference is huge on a bearing of this diameter. As we discussed this further, Scott told me that he was using dial calipers. I told him I had no confidence in measuring clearances this small with dial calipers, but he said he did not have a micrometer available to him.
Scott also told me that it is not uncommon for them to hone the rocker housing when they are installing bearings if they get one that is not smooth. So, there is proof positive for all you guys who thought it was just you. It's not.
So, I will be boxing my trunion upgrade kit to send to Comp Cams for inspection and possible replacement.
I will keep you posted as we learn more.
Launching!
Joined: Jan 2010
Posts: 283
Likes: 0
From: N. Va
wow...this sucks. So this definitely isn't a do it yourself job to the "average" garage junkie. you really need to be able to measure these things accurately and be able to measure/hone the rocker arm accurately for this "upgrade" to even be sustainable. I don't really like the tech's care-free assessment of the issue either acting as if this was common knowledge. I may just sell my kit for $100 and cut my losses rather than spend more hoping it fits correctly.
At this point, I have come to the conclusion that there is insufficient bearing clearances on my upgraded rockers. Now, I just have to figure out why.
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Verdad Gallardo I sent the rocker kit to the attention of Scott at Comp Cams per his specification last week. The USPS tracking said that Comp Cams received the kit on Monday June 6th around lunch time. As of this morning, Thursday June the 9th, nobody called me back. So, I called and left a message for Scott on Thursday morning. By around 2 PM I still had not received a return phone call. So, I called again. I spoke with somebody named Eric. I told him the whole situation and let him know that I found their follow up and communication to be unsatisfactory. Eric said he would find the kit that I sent in and call me back. It never happened.
I guess my next step is to communicate with somebody at Comp Cams that I feel will care about customer service and follow up.
I guess my next step is to communicate with somebody at Comp Cams that I feel will care about customer service and follow up.
David said that the bearings that I sent him measured to be out of round. He went on to say that he fears that the way they are currently shipping the product may be the culprit and he is looking at improved packaging options to eliminate that potential problem. He is sending me a new bearing kit packaged carefully and shipped assembled on the trunion to protect the bearing shells.
I look forward to trying these out. Hopefully everything will go smoothly. I will keep you all posted.
Back in 2009, I did the Comp Cam Trunion upgrade for my 2000 Firebird , the upgrade worked great, it just takes a little patients.
.
Does anyone out there reading this believe for a sec that packaging/shipping could in You're wildest dreams be the reason they are ending up out of round . That statement by the customer service rep at Comp is something a customer service rep from K-Mart would say about You're lawn furniture wheel being a little out of round ? No?
Teching In
Joined: Dec 2006
Posts: 6
Likes: 0
Interesting thread. The rocker upgrade kit does come in a standard box and the bearings are in a bag, they could definitely get banged around a bit in shipping. I'm glad Comp is working to make this right for the OP, but I'm curious...
I've done a few sets of these, and can't imagine you doing them on a vise. Vise jaws move uncontrollably left and right in relation to each other as you tighten them, even a very nice vise. This will lead to bearing misalignment. A press is a must in my opinion.
The other thing I noticed was that no one mentioned the taper ~ the 'letters'/writing needs to be facing out on the bearings for them to insert properly - this is mentioned explicitly in the instructions. I'm not assuming that's the problem for everyone, but certainly could be.
Like anyone who's ever worked at a machine shop, I cleaned my rockers after pressing out the old bearings and used my favorite motor oil as lube. Did not check for out-of-round on the rockers, bearings, or trunions, and 16/16 turned smoothly on each set that I've done here.
I've done a few sets of these, and can't imagine you doing them on a vise. Vise jaws move uncontrollably left and right in relation to each other as you tighten them, even a very nice vise. This will lead to bearing misalignment. A press is a must in my opinion.
The other thing I noticed was that no one mentioned the taper ~ the 'letters'/writing needs to be facing out on the bearings for them to insert properly - this is mentioned explicitly in the instructions. I'm not assuming that's the problem for everyone, but certainly could be.
Like anyone who's ever worked at a machine shop, I cleaned my rockers after pressing out the old bearings and used my favorite motor oil as lube. Did not check for out-of-round on the rockers, bearings, or trunions, and 16/16 turned smoothly on each set that I've done here.
Does anyone out there reading this believe for a sec that packaging/shipping could in You're wildest dreams be the reason they are ending up out of round . That statement by the customer service rep at Comp is something a customer service rep from K-Mart would say about You're lawn furniture wheel being a little out of round ? No?
I suppose all those FAST 90 TBs, and 918 springs were faulty due to damage during shipping also......LOL
I received the new trunion kit from Comp Cams. It measures exactly the same as the old kit, however, this kit came with two parallel ground, black washers for pressing the bearings in. The package on the washers carries the part number 500612550.
I have also ordered a brand new set of rocker to install this trunion kit into. I will keep you posted when they arrive and I begin the installation.
I have also ordered a brand new set of rocker to install this trunion kit into. I will keep you posted when they arrive and I begin the installation.
Launching!
Joined: Dec 2007
Posts: 256
Likes: 0
From: Geelong, Australia
Got my kit from Summit last week and installed it yesterday, well, most of it. The kit was opened and was missing a bearing and 2 bolts. So far I've got 2 stiff/knotchy inlet rockers but the rest are smooth as silk. Wonderful....