Thickness of valve spring pad

[wsa111]

Does anyone know the thickness of the head under the valve spring on a C or D head. 78-82 era.

How much can the valve spring seat be lowered by machining before you get too close to the water jacket?

Any pictures of a sectioned cast head to show the thickness. Thanks Bill

 

[CNC-Dude]

How much extra installed hgt. do you need,sometimes even just cutting the spring pockets for larger OD springs can hit water.

 

[wsa111]

I need to spot face the seat to at least 1.700". That would be a .020" cut.

 

[CNC-Dude]

I would think that is plenty safe! I was thinking you were looking at .075 or .100 or more, that could be questionable.

 

[ap-engines]

Bill,
I found a cut away pic somewhere online a week or two ago. Scarey thin Also very thin on the rocker side of the pushrod tube. I hope its not too late, I just found this thread.

 

['68falconohio]

I'm a little late too.... but I have a C7 head that has several cracks in it and I tossed it in the bandsaw today. I cut through the exhaust valve guide on cylinder #1. I know this isn't the 78-82 era head you wanted but you asked for C or D. Also, if anyone would like to see a cross section of a different part of the head, tell me where to cut and I'll get you some pics.

Stephen

 

['68falconohio]

Alright, I know the intake section view is in the sticky above..but here's the intake on #1 of a C7 log head.

Valve Spring Seat Intake #1 C7 log

Lastly, Water Jacket to Mating Surface of log head on Intake #1 cylinder C7 log. I don't know if this head had been under the knife before and I didn't CC the chambers. But figured this dimension would be good to know.

Stephen