Valve springs for 1968 Chrysler 300- 440

BigBlue

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This is my first post. I’ve pulled the 440 engine in my 1968 Chrysler 300 due to a few oil leaks and I had just purchased the car 2 years ago from an older guy who hadn’t run it for years. Everything is in pretty good shape. It looks like the timing chain and sprockets, camshaft and lifters have all been changed but I think they re used the old valve springs. Several of the springs had multiple shims added. So I am needing to replace the valve springs and valve seals. I’m having troubles finding valve springs that have the original specs. They all seem to be much stiffer. These are the least stiffest I could find. Will they work? COMP Cams 924-16: Dual Valve Springs Outer Spring O.D.: 1.509 in. - JEGS High Performance
I’ve included the specs from my service manual.
The second issue I have is the manifold heat control valve. It is missing pieces and I’m having trouble getting a replacement parts. I only drive this car in the summer. Can I just delete it?
This is my first project. I have no mechanical experience but really enjoying the learning experience.
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Ripinator

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This is my first post. I’ve pulled the 440 engine in my 1968 Chrysler 300 due to a few oil leaks and I had just purchased the car 2 years ago from an older guy who hadn’t run it for years. Everything is in pretty good shape. It looks like the timing chain and sprockets, camshaft and lifters have all been changed but I think they re used the old valve springs. Several of the springs had multiple shims added. So I am needing to replace the valve springs and valve seals. I’m having troubles finding valve springs that have the original specs. They all seem to be much stiffer. These are the least stiffest I could find. Will they work? COMP Cams 924-16: Dual Valve Springs Outer Spring O.D.: 1.509 in. - JEGS High Performance
I’ve included the specs from my service manual.
The second issue I have is the manifold heat control valve. It is missing pieces and I’m having trouble getting a replacement parts. I only drive this car in the summer. Can I just delete it?
This is my first project. I have no mechanical experience but really enjoying the learning experience.
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If I was you, I would leave the springs alone for now. It sounds like they were previously set up carefully by someone in the past when the lifters and cam were changed. If the valves aren't floating at high rpm, the springs are fine. And yes. you can just delete the heat riser. I did this with the 440 in my '66, and since I don't drive the car much when it is very cold, it is not a problem.
 

MONC440

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Yes if you have shims under some of the springs that means someone took the time to check spring tension and did the job correctly. Most engines I see they just slap in the cam and lifters and springs and never check them. Then they wonder why their "built" engine can't rev higher than 5000rpm. I agree with Rip if you are not having high (above 4500 rpm) misfire issues I would leave them alone.
 

Davea Lux

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Shims are often added after a valve grind, that would be normal procedure. Shims help compensate for the material removed from the valves and seats as part of the grinding process to keep the valve tension where it should be. Sounds like somebody did the job properly, so leave it alone unless you are having problems as noted above

Dave
 

CBODY67

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Sounds like the car has had a valve job at some point in time, which is good. Not uncommon to see shims used to get the installed spring pressures into factory spec, too. Be glad that it was obviously done "right". Good that the timing chain has been replaced too. One more thing NOT to have to wonder or worry about! Do you see shims on both heads?

The heat riser discussion can bo both ways . . . keep or disable. On our '66 Newport, it stuck about 1/2 open and ran just fine that way. When we got it replaced with Chrysler factory parts, in the 1970s, it stuck in the same place again. A later fix included reaming the supplied bushing to the size of the shaft, so it worked freely. Still, no difference in performance. So, one of those "don't worry about it deals", to me, as long as it isn't stuck closed.

Stock valve springs last well past 100K miles, by observation. Aftermarket springs sometimes fail well before that. Remember, too, that factory OEM parts are usually better in many respects than some aftermarket parts. In other words, the Chrysler engineers validated the parts used in production and sold for replacement parts.

The OTHER thing is that you need to drive, learn about, and enjoy the car rather than worrying about "making it better", because unlike some other brands, they were pretty dang good to start with, from my experiences.

Nice looking car,
CBODY67,
 

BigBlue

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If I was you, I would leave the springs alone for now. It sounds like they were previously set up carefully by someone in the past when the lifters and cam were changed. If the valves aren't floating at high rpm, the springs are fine. And yes. you can just delete the heat riser. I did this with the 440 in my '66, and since I don't drive the car much when it is very cold, it is not a problem.
It was running good with the current springs. Part of the issue with the springs is I didn't realize they were shims and that some had more than one. So after labeling everything meticulously I moved the heads I didn't realize that there were a couple of shims still stuck to it and when they fell off I had no way to tell which ones they were on. So I thought if I just changed all the springs it would be fine. Should I just take the heads to a proper shop and have them re do the shimming or is this something I can do with a spring tester?
 

BigBlue

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Sounds like the car has had a valve job at some point in time, which is good. Not uncommon to see shims used to get the installed spring pressures into factory spec, too. Be glad that it was obviously done "right". Good that the timing chain has been replaced too. One more thing NOT to have to wonder or worry about! Do you see shims on both heads?

The heat riser discussion can bo both ways . . . keep or disable. On our '66 Newport, it stuck about 1/2 open and ran just fine that way. When we got it replaced with Chrysler factory parts, in the 1970s, it stuck in the same place again. A later fix included reaming the supplied bushing to the size of the shaft, so it worked freely. Still, no difference in performance. So, one of those "don't worry about it deals", to me, as long as it isn't stuck closed.

Stock valve springs last well past 100K miles, by observation. Aftermarket springs sometimes fail well before that. Remember, too, that factory OEM parts are usually better in many respects than some aftermarket parts. In other words, the Chrysler engineers validated the parts used in production and sold for replacement parts.

The OTHER thing is that you need to drive, learn about, and enjoy the car rather than worrying about "making it better", because unlike some other brands, they were pretty dang good to start with, from my experiences.

Nice looking car,
CBODY67,
Yes there are shims on both heads. It was running good with the current springs. Part of the issue with the springs is I didn't realize they were shims and that some had more than one. So after labeling everything meticulously I moved the heads and I didn't realize that there were a couple of shims still stuck to it and when they fell off I had no way to tell which ones they were on. So I thought if I just changed all the springs it would be fine. Should I just take the heads to a proper shop and have them re do the shimming or is this something I can do with a spring tester?
I'm loving getting to know more about the car. I've learnt that stock is best for my car which is nice cause it's also the cheapest! Thanks for your time
 

CBODY67

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Anybody with a proper valve spring tester can re-shim things as needed. BUT unless you might have done it before, probably about the only place you might find a proper/traditional spring pressure tester would be at an automotive machine shop.

Even if you bought new springs, they would need to be checked prior to installation, typically. Best to use what you already have.

Enjoy!
CBODY67
 

BigBlue

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rd92west

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The shims are there to get the proper " installed spring height"
I wouldn't get real excited about them unless you plan to be over 4000 rpm on a regular basis.
Yes they are part of a good valve job, but you either need to get access to a couple of special tools or take the heads to a shop and have it done.
 
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