Valve spring differences between roller cam and flat tappet cam.

[Kern Dog]

I have a 1987 318. The heads I had rebuilt are from an earlier 318. I'm curious if I need to use the stock valvesprings from the roller cam engines. My machinist thought that the factory roller cams are really tame and that the flat tappet spec springs would be fine.
What do you all think ?

 

[Professor Fate]

Go with the early flat tappet springs. The roller motors used exhaust valve rotators and those springs are a hair shorter. So just use the standard retainers and springs.

 

[Kern Dog]

Thank you. That saves some time and effort.

 

[TT5.9mag]

I wouldn’t. The roller lifters are heavy and the the stock springs were barely adequate for the stock cam. Mixing and matching used stock springs usually doesn’t end well especially above 5000 rpm. Springs are cheap, engines are not. Buy a set of springs to match your cam.

 

[Kern Dog]

I have the heads from this engine but can't use them. I took a grinder to one to gain clearance for an exhaust manifold and cut through to a water jacket. I can swap those springs over.
The stock 318 2 barrel engines peaked around 4500 rpms.

 

[Darter6]

The stock 318 2 barrel engines peaked around 4500 rpms.

I run the same roller LA 318 in my 88 truck. The head shop did the heads, checked all the stock springs and said they are fine for the stock spec factory roller cam.So I would say at that rpm stock springs will be fine.

 

[Professor Fate]

I have the heads from this engine but can't use them. I took a grinder to one to gain clearance for an exhaust manifold and cut through to a water jacket. I can swap those springs over.
The stock 318 2 barrel engines peaked around 4500 rpms.

I did the same thing, trying to get clearance for an early A manifold- DAYUM, those water jackets are close to the surface. Ruined a nice fresh head, too.

 

[rumblefish360]

If the spring pressure is good…..

 

[PRH]

In my SBI parts book, all non-HP, non-4bbl, non-rotator.......318’s from 67-89 call for the same springs.

 

[MOPAROFFICIAL]

Stock roller spring seat pressure is 80-90 and only 190-200lbs open