452 head transplant help

[Phoenix440]

Have a pair of rebuilt 452 heads I bought recently.
The heads should be an improvement over the 906s that have been removed.
The heads have new guides, some bowl and port clean up and multi angle valve seats, so expecting them to run better than the standard ( worn out) 906s.

The motor has a reasonable cam but the specs are unknown. The car doesn't make power until around 3000 rpm.
The 906 heads that were removed have single springs with dampers and there was one broken spring.
I suspect the springs were inadequate for the cam. The car always ran rich and may have been partly due to valve float.
The new heads have slightly wider diameter single springs with dampers and was told they can handle.480" lift.

Does anyone have an idea of standard spring diameter and how these compare? Just trying to figure if the springs are up to the job before installing.
Springs on 452s when measured with caliper across diameter are almost 7/32" (5./mm) Springs on 906s are 13/64"(4.8mm).

A couple of other questions:
From pics: 906 head with removed valve;, is this a shim on the guide with spring removed, ( cant remove so assume it isn't but trying to figure if shims were installed on old heads).

The heads are the same thickness where the caliper is in the pic.
Does anybody have a standard head they could measure at the same spot. Im trying to see if the heads are shaved and if rocker arms would need shims( none were installed on the original heads)? Measurement on my heads is1/1/64" roughly ( 25.8mm).

I have been watching Nicks videos on youtube and he says 120lbs closed and 230 -280 lbs open spring pressure is good for a 440 with a .450 or .460 lift cam.
Im thinking this is a good guide considering the cam specs are unknown. The 440 is a hp block and may even have the original cam but who knows,any thoughts on this?

Any ideas much appreciated.
Thanks

 

[493 Mike]

Have a pair of rebuilt 452 heads I bought recently.
The heads should be an improvement over the 906s that have been removed.
The heads have new guides, some bowl and port clean up and multi angle valve seats, so expecting them to run better than the standard ( worn out) 906s.

The motor has a reasonable cam but the specs are unknown. The car doesn't make power until around 3000 rpm.
The 906 heads that were removed have single springs with dampers and there was one broken spring.
I suspect the springs were inadequate for the cam. The car always ran rich and may have been partly due to valve float.
The new heads have slightly wider diameter single springs with dampers and was told they can handle.480" lift.

Does anyone have an idea of standard spring diameter and how these compare? Just trying to figure if the springs are up to the job before installing.
Springs on 452s when measured with caliper across diameter are almost 7/32" (5./mm) Springs on 906s are 13/64"(4.8mm).

A couple of other questions:
From pics: 906 head with removed valve;, is this a shim on the guide with spring removed, ( cant remove so assume it isn't but trying to figure if shims were installed on old heads).
The area around the guide is a machined flat for the spring to sit upon.

Use your caliper to measure the tappet at full lift and on the base circle to get the lift. Then multiply by 1.5 (assuming stock rockers are used) to get lift at valve.
Mike

The heads are the same thickness where the caliper is in the pic.
Does anybody have a standard head they could measure at the same spot. Im trying to see if the heads are shaved and if rocker arms would need shims( none were installed on the original heads)? Measurement on my heads is1/1/64" roughly ( 25.8mm).

I have been watching Nicks videos on youtube and he says 120lbs closed and 230 -280 lbs open spring pressure is good for a 440 with a .450 or .460 lift cam.
Im thinking this is a good guide considering the cam specs are unknown. The 440 is a hp block and may even have the original cam but who knows,any thoughts on this?

Any ideas much appreciated.
Thanks

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[Jerry Hall]

452 heads on stock engines are the same heads as 906's, but with hardened seats. What has been changed on them in the last 50 years will have to be figured in out. To me what you have described is basically just a straight swap with upgraded springs.

 

[ruffcut]

Without knowing camshaft lift, how do you know you have the correct valve springs? Sounds like the springs on the 906 head may have had coil bind to break it. Don't really know without more info on the cam. Shot in the dark,so to say.
Lots of help here if you can provide enough info.
Good luck.

 

[PurpleBeeper]

1. What’s important is spring pressure closed & spring pressure open.
2. That’s not a shim, it’s part of the vave guide.
3. If the cam is really unknown, you’re better off with a stiffer spring. Too stiff wears out cams fast, but too weak can cost you an engine
4. Double check for spring “bind” when installed on the motor at maximum cam lift
5. Pushrod length (or if you need/don’t need rocker shins) is best determined with the engine assembled

 

[PRHeads]

The typical intake guide boss on a 452 doesn’t lend itself to a lot of seal options(as they come from Mopar).
I’d also check to see what kind of retainer-to-seal clearance you’re working with.

 

[33 IMP]

Measure your valve lift at the valve on your 906s before you pull em off.