Valve Springs??

[William B.]

Situation: I purchased a 66 327/300 a year ago. The previous owner had the engine updated and converted from flat tappet to roller rockers and had an aggressive Comp Cam installed. He does not have the cam's number. This was not to his taste and tried another Comp cam that was less aggressive. He later tried a Crane Cam that met his OE expectations. The cams were the only engine components that were changed.

My question is: With the valve springs for the original aggressive Comp Cam still in the engine and now there is a OE equivalent cam, do the springs need to be changed? If so what is recommended and where to purchase? Or do I continue to drive as currently configured

Thanks

Ken Bryant

[Duke W.]

Re: Valve Springs??

If it's an OE equivalent 300 HP cam it should pull 18-19"Hg manifold vacuum at 500 in neutral. Measure and post your results. You need to have at least a bit of evidence that it's an OE cam before you select different valve springs. You also need to know if it has OE valve spring retainers or something else.

Duke

[Domenic T.]

Re: Valve Springs??

Another thing that may help is to remove 1 spring and have it tested. when I rebuilt engines I tested all the springs for height and pressure. I still do this with aircraft springs especially to make sure they don't drop a valve.
The cam manufacturer should have the spring info and you can see if your spring matches.

Dom

[William B.]

Re: Valve Springs??

Thanks Duke, at 500 in neutral it's showing a solid 18 on the vacuum gauge. Since I'm not a mechanic, much less and engine expert, this is about the limit of my knowledge. The thought just occurred to me when the previous owner explained his changing the cams he didn't mention the valve springs and I did not know enough to ask the question. I'm quite sure he took the shortest route which to only change the cam. If further information is needed, I'll have to get local help that knows more than I.

[Duke W.]

Re: Valve Springs??

Sounds like assuming an OE cam is okay and OE cams only need OE springs, about 80 pounds on the seat an close to 200 open. Dom's advice to pull at least one spring and measure is a very good idea. Also try to ID the retainers. Aftermarket may cause different installed height and may even need different than OE locks.

Duke