Exaust valves

[coronadon]

1966 Ford Musatng FB Sprint 200. Engine mod's as follows:
Clifford 264H cam w/hydraulic lifter kit,Weber DGES carb with Clifford adapter,Jacobs mileagemaster electronic ignition w/Ultra coil and Energycore wires,Duraspark distributor.Clifford six into one header w/port divider,2 1/4" exaust with Dynomax Ultra Flo muffler # 17282(straight thru),1965 non-smog head. Ported and polished with 1.75 intake and 1.475 exaust valves(complete valve job).
I installed the head only 4200 miles ago and recently blew the head gasket (Felpro) directly between cylinders 3&4 through the fire rings. It blew from 4 into 3 judging from the material displacement.
I have purchased a Corteco composite head gasket from Classic Inlines but have some reservations before I re-assemble. Would appreciate any and all input on the following questions:
1. Since I only enlarged the intake valves,is it possible not enlarging the exaust valves contributed to the blown head gasket, considering the rest of the exaust system?
2. The head was resufaced when I did the valves and port/polish. Recommendations for the Corteco gasket is to shave more off the head to compensate for the additional thickness of the gasket. My concern is removing too much material and screwing up the valve train geometry. I can't find any specs on factory head measurements and how much can safely be removed. How can I tell if I'm removing too much? What's my risk if I don't resurface. There is no degradation on the block or head where the blowout occured.

 

[Lazy JW]

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1. Since I only enlarged the intake valves,is it possible not enlarging the exaust valves contributed to the blown head gasket......

This is not even remotely a possibility, something else caused the blown head gasket but most definitely NOT the stock size exhaust valve.
Joe

 

[coronadon]

.....
1. Since I only enlarged the intake valves,is it possible not enlarging the exaust valves contributed to the blown head gasket......

This is not even remotely a possibility, something else caused the blown head gasket but most definitely NOT the stock size exhaust valve.
Joe

Thanks for you input Joe.

 

[mugsy]

As for your second question, I've had two head that 0.030" was taken off without any problems. I do have an adjustable rockers, so valve train geo is not an issue. And the reason you want to clean the head surface up is to make sure its flat. I've had machine shops take a little as 0.004" off a head. Which isn't enough to really change the CR or valve train geo. And it's possible to measure how flat the head gasket surface is, but its a fairly cheap procedure and the added insurance is worth it. Its more of a cost avoidance thing; how would you feel if you put it all back together and the HG failed again due to a warped surface? You'd be throwing away more money for another gaskets and stuff.

 

[coronadon]

Thanks for your input Mugsy. I just picked my head up from the machine shop. I had em shave .015 off, which is the difference between the crush thickness between the Felpro(.038) and Corteco(.053) head gaskets. The last time I did all the headwork they took off .005 to clean it up, so .020 total now.
I have adjustable rockers so I should be okay on the geometry issue as you stated.
Appreciate your help!