Can I machine the heads for dual coil springs with the heads still on the car?

I have a set of Comp 987 dual coil springs that I want to use, but understand that I have to machine the heads to fit them. Can that be done with the heads on the car? Or would it make too much mess to be worth it?

 

I dont think that's possible. If you dont want to remove the heads, you should be able to find a spring that work with the stock pockets.

 

I guess I'm a little worried about the stesses on a 95k mile shortblock when removing and reinstalling the heads.

I would think that removing the heads from the car would cause the block to change shape and possibly cause bearing problems to arise sooner than if I leave them on the motor.

And I was wrong, I don't have Comp 987's, I have Crane 10308's. They're in a Comp 987 box..

 

I did heads/cam on 110,000 motor and have not spun a bearing yet even after missing gears and spinning to 7000+ several times.

 

I don't think this is a realistic concern. People change heads all teh time. Even if the block does change shape with the heads off, you won't run it like that. When you torque the heads back on it should all be good again.

 

You dont have to machine the heads... you just need to notch the locators where the head casting ridges get in the way. There are between 1 and 2 of these spots per each seat and with a good grinder or metal cutter it doesnt take but a few seconds to shave off enough material for them to clear. The springs OD is the same size as that of the stock springs so they fit fine.

I was told that unless a machine shop has the right tool to open up the seats that it costs quite a bit of time and money to complete the job. Most shops I guess dont have that tool.