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Cylinder head set up

Paul_G

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The 383 is apart prepping for refresh. It ran great, just smoked some and fouled plugs. Great oil pressure. The bottom is in great shape, the heads not so much. They are a set of old 346 heads, each have valves sinking. I have a set of 452 heads from a 78 motor home 440 I would like to use on the 383.

I am re using the cam, Crane HMV 278 2 NC, 222/234, 467/494, LSA 114. My question is the valve springs. First thought is to just swap the springs from the 346 heads in to the 452 heads. The stock springs in the 452 heads are smaller wire diameter that the springs in the 346 heads, stand taller on the work bench next to the springs from the 346 heads, and are a single spring. Like wise the springs in the 346 heads are a larger wire diameter, shorter, and have an inner spring.

Any way to makes sure the springs from the 346 heads are correct for the cam? Who knows what was done in the past? I called Crane, they recommend spring 99839-16 for the HMV 278 2 cam I am reusing.
 
Is the inner spring on your 346 springs flat-sided? If so, it is only a damper spring, to control resonance only, not really increase spring pressure.
The only real way to know, is have a couple of each spring checked on a spring tester, to find out spring pressure and rate, to compare to the recommended spring. An auto machine shop should be able to check out your springs.
It might be easier, and better for peace of mind, to just get the proper new springs .
 
Was there any problem with the sprigs with the 346 heads? 346 and 452 are pretty much the same so unless either head has had the seats machined on either head you'll need to check the heights and make sure they will be OK.

Regardless, I pretty much did what you are asking, I replaced a worn out set of 906 heads with re-done 452s on stock 1968 383. Yes, the 452s I got had puny little springs so I swapped the ones that were on the 906s, seems to work OK. As long as the current set you have are not completely worn out, you should be OK.

But like said above, if you want to eliminate any questions, just get new new springs, they're not that much. That way you are starting from scratch and not trying to make something work.
 
The 452 heads have the gigantic intake guide bosses.
I usually trim that away and cut for posi seals.

3EA4049C-208F-44C9-976B-C7875B3FD216.jpeg 0AE95269-0AFA-47E1-90EB-E45703A781C9.jpeg 0C152381-3754-4C60-9496-6372832210A6.jpeg
 
I believe they are too tall for the OP's application also. They were for mine. Those springs might not go over the guide bosses either IIRC.

I shortened the ones in the pic........ there is enough room for .700+ lift now.
The chunky intake boss doesn’t fit inside the height mic, so to avoid any headaches with set up, I pretty much always cut them down.
 
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