455 valve spring issues. Help
November 26th, 2018, 06:45 PM
#1
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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.
November 26th, 2018, 07:36 PM
#2
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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.
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.
November 26th, 2018, 09:07 PM
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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.
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 09:11 PM.
November 27th, 2018, 06:21 AM
#4
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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
i would like to just replace valve springs and save money if the low comp pistons are an issue
November 27th, 2018, 08:28 AM
#6
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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”
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 08:32 AM.
November 27th, 2018, 08:54 AM
#7
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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👍
Thanks to all who have replied so far👍
November 27th, 2018, 01:56 PM
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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.
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 03:11 PM.
November 28th, 2018, 03:59 AM
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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 ?
November 28th, 2018, 04:14 AM
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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
November 28th, 2018, 09:00 PM
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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
November 29th, 2018, 04:43 PM
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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
September 16th, 2019, 11:03 AM
#19
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Believe it or not the new springs did make a big difference. The engine rev's above 3K now with no issue. BUT still lacks to satisfy on power. The new springs made the car more driver friendly but the car has trouble doing a burnout with 3:23 posi rear. Anyone else have ideas to help perk this BB up without upgrading pistons??
September 16th, 2019, 04:50 PM
#20
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As you mentioned, above especially now that the motor responds better with the new springs=Keep your foot out of it. I'm assuming its a A-body car your talking about ( Cutlass) a 3:23 rear is not going to set your rear tires on fire, unless the power is there.
September 16th, 2019, 07:45 PM
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September 17th, 2019, 04:10 AM
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x2 my 455 in a 76 supreme will roast the tires with a 2;56 posi ,and its still has the low compression pistons in it.you may want to try advancing timing in 2 degree increments to see if the power improves
September 19th, 2019, 12:49 PM
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If you haven't already, try Eric's suggestion. If it works, and you don't already have one, an adjustable vac advance can is a cheap, easy to install upgrade. Just follow the directions and keep adding in vac advance until the engine starts to surge or ping. Then back it off a little. How much vac advance you end up with will depend on your timing curve and how much initial advance you are running.
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