Diagnosing Valve Train Clatter
Cargo Master
Joined: Dec 2015
Posts: 2,543
Likes: 322
From: Harned, Ky
Yes the springs for the valve rotators are different and have a coil bind height of 1.220 verses the non rotators spring bind at 1.330
So there you go, one can not trust the stock springs unless you physically measure them with a spring tester, something the average shop doesn't do unless requested
The spring you have recommended is similar to the Melling VS280 that's recommended for that cam
As I stated install the recommended springs, or ones from a different maker with similar specs like what you have now recommended
I will add that before using stock springs on cams nearing or exceeding .500 lift have them tested, you won't get spring pressures but one can check lift capabilities and coil bind height with a vice and pair of calibers.
So there you go, one can not trust the stock springs unless you physically measure them with a spring tester, something the average shop doesn't do unless requested
The spring you have recommended is similar to the Melling VS280 that's recommended for that cam
As I stated install the recommended springs, or ones from a different maker with similar specs like what you have now recommended
I will add that before using stock springs on cams nearing or exceeding .500 lift have them tested, you won't get spring pressures but one can check lift capabilities and coil bind height with a vice and pair of calibers.
Cargo Master
Joined: Oct 2020
Posts: 2,675
Likes: 784
Yes the springs for the valve rotators are different and have a coil bind height of 1.220 verses the non rotators spring bind at 1.330
So there you go, one can not trust the stock springs unless you physically measure them with a spring tester, something the average shop doesn't do unless requested
The spring you have recommended is similar to the Melling VS280 that's recommended for that cam
As I stated install the recommended springs, or ones from a different maker with similar specs like what you have now recommended
I will add that before using stock springs on cams nearing or exceeding .500 lift have them tested, you won't get spring pressures but one can check lift capabilities and coil bind height with a vice and pair of calibers.
So there you go, one can not trust the stock springs unless you physically measure them with a spring tester, something the average shop doesn't do unless requested
The spring you have recommended is similar to the Melling VS280 that's recommended for that cam
As I stated install the recommended springs, or ones from a different maker with similar specs like what you have now recommended
I will add that before using stock springs on cams nearing or exceeding .500 lift have them tested, you won't get spring pressures but one can check lift capabilities and coil bind height with a vice and pair of calibers.
Thread Starter
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Laughing Gas
Joined: Aug 2010
Posts: 1,049
Likes: 230
From: Amarillo, TX
My intake & exhaust springs seem Identical, as well as valve stems & retainers.. Going to take my head up to a machine shop to get precise measurements to select the proper springs. I'm way in over my head here trying to pick out anything other than a stock replacement
Laughing Gas
Joined: Dec 2020
Posts: 869
Likes: 186
From: Near my truck
Cam manufacturers usually provide specifications for springs with their cams.
You can give your cam specs to Melling and ask them for the spring specifications.
Failing that, Edelbrock, Summit, and others I think, supply cams with the exact same lift as your cam, so those specs can be used.
If that fails, say so, and I'll post up part numbers for EXACT springs for your cam.
Each spring must be checked for a given pressure at a given height, and shims, to an extent, may be used to correct any that are out of spec.
Ensure that you, or your machine shop, does this, especially as there is a specific simple tool to do so.
Replace ALL of the springs.
Without realizing it, you already stated in your first post why your one spring failed.
Cargo Master
Joined: Dec 2015
Posts: 2,543
Likes: 322
From: Harned, Ky
Exact Melling springs for his cam are the ones I listed # VS280.
Looked them up in my 1991 & earlier Melling parts book I picked up at the PRI trade show in Indianapolis a couple years ago
Looked them up in my 1991 & earlier Melling parts book I picked up at the PRI trade show in Indianapolis a couple years ago
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Cargo Master
Joined: Oct 2020
Posts: 2,675
Likes: 784
Why would you run that spring when a stock spring is really a better fit?
Cargo Master
Joined: Dec 2015
Posts: 2,543
Likes: 322
From: Harned, Ky
Because he doesn't have the stock springs your talking about, he doesn't have the valve rotator or the smaller springs it takes
He probably has the ones like the Cleveland springs you mentioned
And I didn't say to run those springs, I said that's the ones Melling recommended
He can go with the Qualcast 32-909-D springs you recommended for all I care
He probably has the ones like the Cleveland springs you mentioned
And I didn't say to run those springs, I said that's the ones Melling recommended
He can go with the Qualcast 32-909-D springs you recommended for all I care
Laughing Gas
Joined: Dec 2020
Posts: 869
Likes: 186
From: Near my truck
Sorry ! I had initially read your earlier VS280 suggestion, but forgot about it when I posted later. 
Logistics Pro
Joined: May 2015
Posts: 4,469
Likes: 964
From: Tri Cities, TN
This is what you have stock: INT. D1AZ-6513-A, closed 80# @ 1.820, open 226 @ 1.39, solid @ 1.33
EXH. D8AZ-6513-A, closed 45# @ 1.8, open 205 @ 1.3, solid @ 1.22
The VS280 is closed 85# @ 1.82, open 270 @ 1.32, solid @ 1.26
Prior to 1978 the 400's used the D1AZ spring on both valves without the rotators on the exh.
Buy yourself a decent set of springs.
And get rid of those rotators. I doubt the things ever worked anyway.
Last edited by Crop Duster; Apr 6, 2022 at 05:28 AM. Reason: more words
Cargo Master
Joined: Oct 2020
Posts: 2,675
Likes: 784
They can't be identical if you have rotators on the exhaust. Destroked450 is right the Melling VS280 is what is recommended for your cam. That spring is the same spring used on 351C 4bbl engines and 428 FE's.
This is what you have stock: INT. D1AZ-6513-A, closed 80# @ 1.820, open 226 @ 1.39, solid @ 1.33
EXH. D8AZ-6513-A, closed 45# @ 1.8, open 205 @ 1.3, solid @ 1.22
The VS280 is closed 85# @ 1.82, open 270 @ 1.32, solid @ 1.26
Prior to 1978 the 400's used the D1AZ spring on both valves without the rotators on the exh.
Buy yourself a decent set of springs.
And get rid of those rotators. I doubt the things ever worked anyway.
This is what you have stock: INT. D1AZ-6513-A, closed 80# @ 1.820, open 226 @ 1.39, solid @ 1.33
EXH. D8AZ-6513-A, closed 45# @ 1.8, open 205 @ 1.3, solid @ 1.22
The VS280 is closed 85# @ 1.82, open 270 @ 1.32, solid @ 1.26
Prior to 1978 the 400's used the D1AZ spring on both valves without the rotators on the exh.
Buy yourself a decent set of springs.
And get rid of those rotators. I doubt the things ever worked anyway.
