I threw a shim, what happened!?!?

Q&A regarding engines, turbos, and intercoolers and power upgrades

I threw a shim, what happened!?!?

Postby FWD-3SGTE » Sat Jun 23, 2012 2:36 am

Project with no name here!

So I took the car on the highway last night, did a 3rd gear pull and the car hit a brick wall at 7k rpm. This is what I found when I took the valve cover off...

Shim...

Image

Cam position as is...

Image

Cam position after I turned it a bit. Notice the bucket didn't spring back up toward the cam...

Image

Parts are all aftermarket besides the shims and buckets. HKS cams, HKS valve springs and Ferrea valves.

Now, I'm not sure what started the chain reaction, did the cam throw a shim or did something else break which caused the shim to get tossed? Did I break a spring? Bend a valve? I'm confused. I wouldn't think that the cam would throw a shim at 7k, my cam to shim clearances were in spec as of the last time I checked so I'm not sure what happened.

I wanted to post this to hear your thoughts before I take the head off, which is a given, but still.

Thanks :)
Members don't see the above ad. Register now - it's free!
FWD-3SGTE
Club Member
 
Posts: 845
Joined: Fri Sep 03, 2004 11:41 pm
Location: Enfield, CT

Re: I threw a shim, what happened!?!?

Postby 4rsnduction » Sat Jun 23, 2012 3:02 am

Most common reason for having a shim fly off the top of the bucket is the cam lobe to shim clearance is incorrect.
The gap between the shim and the bottom of the lobe at full stroke needs to be tailored so the lobe dosnt strike too much surface area of the shim....striking a larger area helps the lobe dig into the shim, all this force causes the shim to be displaced at higher rpm.

What are your clearances for the rest of the shims ?
User avatar
4rsnduction
Club Member
 
Posts: 452
Images: 0
Joined: Mon Jan 09, 2012 11:57 pm
Location: Sydney, Australia

Re: I threw a shim, what happened!?!?

Postby esracing » Sat Jun 23, 2012 3:08 am

f*** the head needs to come off to fix the bucket area of the head.most people do the under bucket style shim .what lift and deration cams 272 ,264?
2008 tundra blue
1988 st165 white imsa gto
1969 camaro 502 bb 630 hp black
esracing
Club Member
 
Posts: 804
Joined: Mon Dec 20, 2004 2:19 pm
Location: maryland

Re: I threw a shim, what happened!?!?

Postby esracing » Sat Jun 23, 2012 3:10 am

the valve mite be bent now because its not returned up al the way.
2008 tundra blue
1988 st165 white imsa gto
1969 camaro 502 bb 630 hp black
esracing
Club Member
 
Posts: 804
Joined: Mon Dec 20, 2004 2:19 pm
Location: maryland

Re: I threw a shim, what happened!?!?

Postby FWD-3SGTE » Sat Jun 23, 2012 4:56 am

4rsnduction wrote:Most common reason for having a shim fly off the top of the bucket is the cam lobe to shim clearance is incorrect.
The gap between the shim and the bottom of the lobe at full stroke needs to be tailored so the lobe dosnt strike too much surface area of the shim....striking a larger area helps the lobe dig into the shim, all this force causes the shim to be displaced at higher rpm.

What are your clearances for the rest of the shims ?

I'll have to check the clearances over the next few days. I checked the clearances a couple of months ago because the head is a bit noisy after the build but everything was well in spec.

esracing wrote:f*** the head needs to come off to fix the bucket area of the head.most people do the under bucket style shim .what lift and deration cams 272 ,264?

If I could go back, I would do the shimless bucket conversion but didn't think it would be problem because I'm not revving overly high. Cams are 264's.

esracing wrote:the valve mite be bent now because its not returned up al the way.

That's what I'm afraid of.
FWD-3SGTE
Club Member
 
Posts: 845
Joined: Fri Sep 03, 2004 11:41 pm
Location: Enfield, CT

Re: I threw a shim, what happened!?!?

Postby 4rsnduction » Sat Jun 23, 2012 8:45 am

FWD-3SGTE wrote:
4rsnduction wrote:Most common reason for having a shim fly off the top of the bucket is the cam lobe to shim clearance is incorrect.
The gap between the shim and the bottom of the lobe at full stroke needs to be tailored so the lobe dosnt strike too much surface area of the shim....striking a larger area helps the lobe dig into the shim, all this force causes the shim to be displaced at higher rpm.

What are your clearances for the rest of the shims ?

I'll have to check the clearances over the next few days. I checked the clearances a couple of months ago because the head is a bit noisy after the build but everything was well in spec.


Stock clearance numbers will not apply to after market cams because the lobe profile is different, this makes the clearance gap different, an experienced machinist or head specialist will be able to get satisfactory clearances because they do it day in day out and also have the correct machinery and tools
User avatar
4rsnduction
Club Member
 
Posts: 452
Images: 0
Joined: Mon Jan 09, 2012 11:57 pm
Location: Sydney, Australia

Re: I threw a shim, what happened!?!?

Postby FWD-3SGTE » Wed Jun 27, 2012 12:39 am

Gotcha.

Well, I furthered inspected, a little. I removed the intake manifold and was able to slightly peek in side the head with a mirror and it doesn't look like a valve is bent. I'm not sure when I will be pulling the head but I will keep this up to date, as best I can.
FWD-3SGTE
Club Member
 
Posts: 845
Joined: Fri Sep 03, 2004 11:41 pm
Location: Enfield, CT

Re: I threw a shim, what happened!?!?

Postby tubasteve » Wed Jun 27, 2012 1:31 am

What retainers did you use? I know Brian Crower sells two types of retainers. I spit a Sim two years ago, stock cams and head work....was 16 psi deep in third rounding a freeway clover when mine went it ten another three miles, cause i couldn't hear it. Checked shims leak down, and cam...its still running fine with longer harder pulls than that.
feb. 1990 alltrac red one: fun machine http://tinyurl.com/Tubasteve
5x114 conversion: http://tinyurl.com/nu3qnez
Image
User avatar
tubasteve
Established Member
 
Posts: 1149
Joined: Tue Apr 01, 2008 6:48 pm
Location: temecula, ca(951)

Re: I threw a shim, what happened!?!?

Postby klue » Wed Jun 27, 2012 1:34 am

you use the stock valve clearance regardless of what cam, thats to maintain an oil film. From where it popped out I would be checking if your cam is also bent. Do you have the high lift cam? with a 264 duration keep in mind your putting alot of stress on the shim for a longer period of time, it also rolls open and closed faster than oem. Im running stock shims on gen 3 cams up to 7800 rpm no issues, on 264 up to 8,000.

my guess you had an assembly issue, or a cam issue
facebook.com/xiiimotorsports
#xiiimotorsports ON instagram
User avatar
klue
GTFour God
 
Posts: 3893
Joined: Thu Nov 04, 2004 9:47 pm
Location: Greater Toronto Area

Re: I threw a shim, what happened!?!?

Postby tubasteve » Wed Jun 27, 2012 1:37 am

I'd ask next, how old is the head rebuild?
feb. 1990 alltrac red one: fun machine http://tinyurl.com/Tubasteve
5x114 conversion: http://tinyurl.com/nu3qnez
Image
User avatar
tubasteve
Established Member
 
Posts: 1149
Joined: Tue Apr 01, 2008 6:48 pm
Location: temecula, ca(951)

Re: I threw a shim, what happened!?!?

Postby FWD-3SGTE » Wed Jun 27, 2012 1:51 am

I believe that I had new OEM retainers installed.

I don't know if I have the high lift cam, I just know they're HKS 264's. The shim was thrown at 7k rpm, I thought it was odd.

The whole build has less than 2k miles on it, I don't drive it much. The head was a noisy fella though, not sure why, all clearances were well within spec, maybe too tight? Idk what causes loud ticking other than faulty cam clearances, are any of your built heads noisy?
FWD-3SGTE
Club Member
 
Posts: 845
Joined: Fri Sep 03, 2004 11:41 pm
Location: Enfield, CT

Re: I threw a shim, what happened!?!?

Postby tubasteve » Wed Jun 27, 2012 4:11 am

FWD-3SGTE wrote:I believe that I had new OEM retainers installed.

I don't know if I have the high lift cam, I just know they're HKS 264's. The shim was thrown at 7k rpm, I thought it was odd.

The whole build has less than 2k miles on it, I don't drive it much. The head was a noisy fella though, not sure why, all clearances were well within spec, maybe too tight? Idk what causes loud ticking other than faulty cam clearances, are any of your built heads noisy?



No, I'm uploading what i think happened. Pull the bucket out...you'll find your reason. I had a bucket float before and get wedged, turned out the bucket was out of round. I'm gong to 1zz $him le$$
feb. 1990 alltrac red one: fun machine http://tinyurl.com/Tubasteve
5x114 conversion: http://tinyurl.com/nu3qnez
Image
User avatar
tubasteve
Established Member
 
Posts: 1149
Joined: Tue Apr 01, 2008 6:48 pm
Location: temecula, ca(951)

Re: I threw a shim, what happened!?!?

Postby tubasteve » Wed Jun 27, 2012 4:21 am

Image

Image

Image

Image

The head is gen 2, with shimless titanium valve spring retainers.
feb. 1990 alltrac red one: fun machine http://tinyurl.com/Tubasteve
5x114 conversion: http://tinyurl.com/nu3qnez
Image
User avatar
tubasteve
Established Member
 
Posts: 1149
Joined: Tue Apr 01, 2008 6:48 pm
Location: temecula, ca(951)

Re: I threw a shim, what happened!?!?

Postby FWD-3SGTE » Wed Jun 27, 2012 6:30 am

Let's say the bucket was out of round and got wedged, do you think the head is damaged by that, being "soft" aluminum and all?
FWD-3SGTE
Club Member
 
Posts: 845
Joined: Fri Sep 03, 2004 11:41 pm
Location: Enfield, CT

Re: I threw a shim, what happened!?!?

Postby tubasteve » Wed Jun 27, 2012 2:26 pm

I'd worry less about your head, more about the valve that might not be closed.
feb. 1990 alltrac red one: fun machine http://tinyurl.com/Tubasteve
5x114 conversion: http://tinyurl.com/nu3qnez
Image
User avatar
tubasteve
Established Member
 
Posts: 1149
Joined: Tue Apr 01, 2008 6:48 pm
Location: temecula, ca(951)

Next

Return to Performance and Power

Who is online

Users browsing this forum: No registered users and 3 guests