You can type here any text you want

Replacing valve springs...

  • Thread starter Thread starter coach
  • Start date Start date

Welcome!

By registering with us, you'll be able to discuss, share and private message with other members of our community.

SignUp Now!
C

coach

Guest
Hi Guys,
I am replacing the OEM springs on my car and had a question. I ordered a set from Mike at FULL THROTTLE. He sent me Comp cams #980-12. They say 92# @ 1.700", 308#/ inch spring rate. I was told by a friend that when you do this with heads on the motor, it is hard to get the shields back on the new springs. He said if you do not reuse the shields, you need to add shims to make up the thickness of the bottom of the shield. He thought it was about a .062 shim. Is it necessary to shim? Is there a way to tell if what I got accounts for the shield not being used? He said that most people do not put the shields back on, so I need to know if the seat pressure will be OK.

Thanks
Coach
 
Need to know the present Installed Height to calculate your actual spring pressure and go from there. If you need more then what you will wind up with, without the shields, then get some shims. 0.062" will change the open and closed pressure almost 20#'s
 
Would it be same as all 3.8 turbos? This is 18,000 mile engine, never apart. This engine is together. Am I correct on the .062 being the amount of the shields? I am callin Mike tomorrow to see if he knows if these are for shields or without.

Thanks
Coach
 
If the 'shields' you are referring to are the 'cups' the springs sit in, it's my understanding, after much reading/research here and other places, that when using the Comp 980's as an OEM replacement (stock cam) the cups should not be used. This will reduce the spring load back closer to (but still above) the Comp 979's which are the closest springs to OEM available from comp., and which are also slightly stiffer than stock. Here's some reading that ought to cover it.... :cool:
http://www.turbobuick.com/forums/general-turbo-buick-tech/234050-these-valve-spring-dampers.html

HTH....
 
Hi Guys, just came from parts store. They only list intake valve seals. Whats up? I have not heard of this.

Thanks
Coach
 
Thats right we only have intake valve seals and the xh has NONE.
If you think about it when does the exhaust ever have vac on it.
Inorder to place seals on teh exh side the guides have to be cut down
 
I put a set on my old WH-1 and didnt look back. Didnt use the cups, and had no negative effects to the motor. And it had 135K on it at the time. I picked up .2 at Cecil, BTW.

Worked great, really woke up the car. Valve seals are a good precaution as well.
 
scojack_2001 said:
I put a set on my old WH-1 and didnt look back. Didnt use the cups, and had no negative effects to the motor. And it had 135K on it at the time. I picked up .2 at Cecil, BTW.

Worked great, really woke up the car. Valve seals are a good precaution as well.
Click to expand...

A set of ?? 980's or the 979's?
 
I used 980's with no cups for 4 years on a 90,000 mile motor and a 100 1/4 passes with no issues.
 
I did read your post.I thought you were only talking about the factory style seals that fit tight over the valve guide.I know that the guide would need to be cut down to use those.I was hoping maybe somebody tried umbrella seals and they maybe worked.but i guess that they wont.
 
Thanks for the help. I feel alot better knowing that my 980's will be ok without the cups. I am changing them out on Saturday.

Thanks
Coach
 
Before I start this, what is proper way to remove rocker shafts? Do they torque to a specific foot-puonds when reinstalled? Are new bolts required, or anything special? My buddy at the parts store said that you can run the intake seals on both. Would this hurt anything?

Thanks
Coach
 
The intake seal wont fit on the exhaust valve guides unless they have been machined down.I am also trying to find something that would work without cutting them down.I get a big old puff of smoke when i start the car because i didnt put anything on them like the factory.
 
The exhaust valve stem has a flat bottomed groove machined into it. This groove travels into and then out of the valve guide every time the valve is opened and closed. I tried to put a seal on the exhaust valve, but found that when that groove contacts the seal it chews it up as the valve cycles. I would think that if one has aftermarket valves with a stem that is a uniform diameter the entire lenght a seal would work, but I don't see how it will on a stock valve. When you go back together, tighten each rocker arm shaft bolt a little at a time until the shaft is seated in their pedestals, then torque to 35 pounds.
 
You must log in or register to reply here.

Similar threads

J
Trouble with valve springs
6
1K
BUICKTIME
BUICKTIME
B
Rear Diff. clutch pack replacement.
2
844
brandnu6
B
F
Scam or Not?
2
26
996
T-type Jones
T-type Jones
G
100,000 mile engine service - a few questions
11
1K
granitestategn
G
M
Flange Thickness on 3" Terry Downpipe
2
731
MCH86GN
M

Online statistics

Members online
23
Guests online
318
Total visitors
341
Totals may include hidden visitors.

Newest members

Stay Connected

Back
Top