455 valve spring issues. Help - ClassicOldsmobile.com

455 valve spring issues. Help

Old November 26th, 2018, 07:45 PM
  #1  
Registered User
Thread Starter
 
Join Date: Apr 2010
Location: Middletown Pa
Posts: 7
455 valve spring issues. Help

Bought a 455 used. Heard it running and sounded fine. After running it in my car I found out why it was sold. Looses power/flats out above 3000 rpm. Being told valve springs are too weak. My question is if I buy a new cam/lifters/ springs. Can I install them without pulling heads and having machine shop work done. Looking at Lunati grind. 499 intake. 511 exhaust. C heads.
2170mark is offline  
Old November 26th, 2018, 08:36 PM
  #2  
Registered User
 
Fun71's Avatar
 
Join Date: Feb 2013
Location: Phoenix, AZ
Posts: 5,906
Yes, you can do a cam/lifter swap without pulling the heads.
Why not just replace the valve springs, assuming that is really what's wrong? Seems odd to sell an engine because the valve springs are too weak, though.
Fun71 is online now  
Old November 26th, 2018, 10:07 PM
  #3  
Registered User
 
Join Date: Mar 2011
Posts: 415
Which pistons? 14cc or 40cc?

I have an Erson single pattern 228 @ .050” on a 108 LSA cam, lifter, and spring kit that I bought from cutlassefi on this site and it pulls HARD. Through 5,000 RPM.

Lift is .504” and you don’t need to do anything to the heads besides put on springs

It needs 9.5:1 compression or better though. If you have 14cc pistons you should have the compression.


Last edited by VinMichael; November 26th, 2018 at 10:11 PM.
VinMichael is online now  
Old November 27th, 2018, 07:21 AM
  #4  
Registered User
Thread Starter
 
Join Date: Apr 2010
Location: Middletown Pa
Posts: 7
I have learned since purchase it has L2390 .030 low comp pistons in it. Do you think the Lunati 10420702 at 499 int and 511 exh is too much cam??
i would like to just replace valve springs and save money if the low comp pistons are an issue
2170mark is offline  
Old November 27th, 2018, 07:48 AM
  #5  
Registered User
 
Join Date: Mar 2008
Posts: 3,426
I have seen cases where an intake gasket leak caused the power loss over 3000 or 3500 rpm.
Run to Rund is offline  
Old November 27th, 2018, 09:28 AM
  #6  
Registered User
 
Join Date: Mar 2011
Posts: 415
Your compression ratio is very low with those pistons. I would save the money and just replace the valve springs.

FYI the C heads have shorter spring pockets than the others. They should be around 1.680” installed, opposed to 1.800”

Last edited by VinMichael; November 27th, 2018 at 09:32 AM.
VinMichael is online now  
Old November 27th, 2018, 09:54 AM
  #7  
Registered User
Thread Starter
 
Join Date: Apr 2010
Location: Middletown Pa
Posts: 7
That's what I'm thinking. Use this motor and keep my foot out of it till I can build a high comp motor. I have a 68 455 sitting in pieces I bought Any recs to build a great street motor??

Thanks to all who have replied so far👍
2170mark is offline  
Old November 27th, 2018, 02:56 PM
  #8  
Registered User
 
Join Date: Mar 2011
Posts: 415
There are a few Olds vendors that you can call, though I’ve only dealt with one. Mark - “cutlassefi” is a memeber here and I’ve bought many parts through him with excellent results. He also has built quite a few engines for members here.

But if you have a good machinist then you might consider assembling yourself.

My biggest hurdle with building engines has been finding a good machinist. But I think I’ve finally found the right people. One guy does the machining on the block, and balances the rotating assembly. And I have another guy do the valve seats with a Serdi.

I highly recommend Procomp or Edelbrock heads. And Eagle H beam rods for almost any build.

Last edited by VinMichael; November 27th, 2018 at 04:11 PM.
VinMichael is online now  
Old November 28th, 2018, 04:59 AM
  #9  
Registered User
 
Join Date: Dec 2016
Posts: 221
Originally Posted by 2170mark View Post
Looses power/flats out above 3000 rpm. Being told valve springs are too weak.
I don't think I have ever seen valve springs cause a problem at that low of an rpm. I doubt seriously that they are the problem.

I think you need to do some more troubleshooting. My first bet would be running out of fuel. Could also be ignition timing.

What carburetor and distributor setup is on it ?
BillK is offline  
Old November 28th, 2018, 05:14 AM
  #10  
Registered User
Thread Starter
 
Join Date: Apr 2010
Location: Middletown Pa
Posts: 7
I've been all over the fuel issue. New reproduction fuel lines from front to back. Multiple carb changes. Multiple fuel pump options. No real improvement. Then a guy changed the valve springs with a set he had off another Olds. Definitely improved but not100%. Then one of those valve springs broke. The current carb is a 70 quadrajet and distributor is a GM HEI. Both carb and dist were gone over by Cliffs Performance
2170mark is offline  
Old November 28th, 2018, 12:39 PM
  #11  
Registered User
 
Fun71's Avatar
 
Join Date: Feb 2013
Location: Phoenix, AZ
Posts: 5,906
I just did a quick search and a set of valve springs is $70, so why not try a new set of known-good springs?
Fun71 is online now  
Old November 28th, 2018, 01:08 PM
  #12  
Registered User
 
Join Date: Aug 2011
Posts: 567
How is the exhaust system, any chance of a restriction?
Good luck!!!
Sugar Bear is offline  
Old November 28th, 2018, 01:12 PM
  #13  
Registered User
Thread Starter
 
Join Date: Apr 2010
Location: Middletown Pa
Posts: 7
I ordered a set of springs. Hope to install this weekend. Exhaust is new including manifolds back. No worries there
2170mark is offline  
Old November 28th, 2018, 08:25 PM
  #14  
Registered User
 
Join Date: Aug 2011
Posts: 567
Are you replacing the valve stem seals at the same time?
Sugar Bear is offline  
Old November 28th, 2018, 10:00 PM
  #15  
Registered User
Thread Starter
 
Join Date: Apr 2010
Location: Middletown Pa
Posts: 7
When I removed the broken spring I looked at the seal for damage. Thinking the retainer may be hitting it. It looked great with no damage. Your suggesting I replace the seals while the springs are off?? Sounds like a good idea. Can't be too much for added insurance. Thanks
2170mark is offline  
Old November 29th, 2018, 01:05 AM
  #16  
Registered User
 
Join Date: Aug 2011
Posts: 567
Yes, I would replace them while the springs are removed.

Good luck!!!
Sugar Bear is offline  
Old November 29th, 2018, 12:14 PM
  #17  
Registered User
 
Join Date: Mar 2011
Posts: 415
Curious to know if that fixes your problem. Let us know what happens.
VinMichael is online now  
Old November 29th, 2018, 05:43 PM
  #18  
Registered User
Thread Starter
 
Join Date: Apr 2010
Location: Middletown Pa
Posts: 7
If the weather conditions are OK I may be able to drive it. Here in PA you just don't know from one day to the next. When I know I will definitely post an update. Springs arrived yesterday Thank You for your input guys
2170mark is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Battenheaded67
Parts For Sale
8
April 6th, 2018 06:44 PM
johnnyjaws
Big Blocks
2
February 23rd, 2015 05:30 PM
Longhorncutlass
General Discussion
4
March 2nd, 2009 02:53 PM
cts-v
Big Blocks
5
February 28th, 2009 10:05 AM
cts-v
Big Blocks
1
December 30th, 2008 08:34 PM


Thread Tools
Search this Thread
Quick Reply: 455 valve spring issues. Help


Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.