The Ford Barn

Ol' Ron · 05-18-2023, 07:35 AM

Great job Zig. I'm trying to find a shope near me to Braze fill smoe part of the combustion chamber. I have a way to move the spark plug, and angle milling is pretty common today. The results would be a 258 with 9:1 cR and better breathing thhan any aftermarket head at 1/2 the price. Thus was a common modification to a stock head back in the 50s&60s the Danbery rules said NO aftermarket heads. This was to reduce the cost of racing. After this rule was eliminated, we went to the aftermarket and found the these heads limited RPN power. I think the stock heads have some class.
Gramps

Ziggster · 05-18-2023, 08:24 AM

Thanks. I’m just a novice, but it is websites like this and folks like you that are willing to share their knowledge that has made this an incredible journey. I agree that raising the CR will be important in raising hp. I was actually surprised to see the sparkplug indentation over the exhaust valve. You certainly wouldn’t expect that looking at the head. I think with my setup (0.060” with the stk 3.75” stroke, and the C7RA stk heads), my CR is a measly 7.14. Good enough for my purposes, but certainly not where you want it to be if more power is your goal.

Ronnieroadster · 05-18-2023, 01:58 PM

Quote:

Originally Posted by Ziggster

Thanks. I’m just a novice, but it is websites like this and folks like you that are willing to share their knowledge that has made this an incredible journey. I agree that raising the CR will be important in raising hp. I was actually surprised to see the sparkplug indentation over the exhaust valve. You certainly wouldn’t expect that looking at the head. I think with my setup (0.060” with the stk 3.75” stroke, and the C7RA stk heads), my CR is a measly 7.14. Good enough for my purposes, but certainly not where you want it to be if more power is your goal.

You did an outstanding job documenting with pictures how easy it is using clay to get the actual dimensions. Also seeing what's going on with the spark plug is a great example of how things can get interesting inside such a simple combustion chamber.

When it comes to spark plugs especially with the NGK brand which I prefer over all others I always add one more spark plug washer. This helps reduce the possibility of the valve coming in contact with the plug electrode if I miss a shift. Funny things happen when the revs are getting near 6 grand valves like to float.

Ronnieroadster

Jack E/NJ · 05-18-2023, 07:07 PM

Ol'Ron>>>angle milling is pretty common today>>>

Still worry a bit about studs & bolts without enlarging the holes. I'd rather mill flat & install an angled gasket with an angle of my choosing. 8^)

Ziggster · 05-19-2023, 06:17 AM

Quote:

Originally Posted by Ronnieroadster

You did an outstanding job documenting with pictures how easy it is using clay to get the actual dimensions. Also seeing what's going on with the spark plug is a great example of how things can get interesting inside such a simple combustion chamber.

When it comes to spark plugs especially with the NGK brand which I prefer over all others I always add one more spark plug washer. This helps reduce the possibility of the valve coming in contact with the plug electrode if I miss a shift. Funny things happen when the revs are getting near 6 grand valves like to float.

Ronnieroadster

Thanks Ronnie. That’s quite the compliment coming from you.

Bored&Stroked · 05-20-2023, 01:28 PM

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One thing to note on the valve clearance: You need to check BOTH sides of the engine. Due to the different valve angles (side to side), the valves on the driver's side are usually about .040 or so higher than the passenger's side. The area you are most concerned about is all the way at the top.

Piston to head clearance: Given that you're at .073 or so, if it was my engine, I'd have the heads shaved to reduce the clearance to 0.045 (minimum for all areas over the piston crown). This is the final quench dimension - with the head gasket in place.

Valve to Head Clearance: As you noted, due to the valve angle, they are closest to the head at the very tops. So, if you mill the heads .030, then depending on your final measurements, you may need to do the manual clearance work on the heads for valve clearances at the top of the chambers. The amount you have to clearance will usually be different on one head versus the other (again, due to valve angles the valve heights are different as they relate to the deck).

Manual Head Clearance Work - for Tops of Valves: I'd use a carbide tool to rework the TOPs of the chambers (the eyebrow area) to give myself about .060 over the tops of the valves (to the head). If you need any examples of the type of bits I use, just ask. I can't remember if your heads are aluminum or cast-iron (while writing this), so the types of rotary files/bits to use will differ depending on the head material.

05-18-2023, 07:35 AM	#21
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,862	Re: Safe Way to Check Valve-Head Clearance? Great job Zig. I'm trying to find a shope near me to Braze fill smoe part of the combustion chamber. I have a way to move the spark plug, and angle milling is pretty common today. The results would be a 258 with 9:1 cR and better breathing thhan any aftermarket head at 1/2 the price. Thus was a common modification to a stock head back in the 50s&60s the Danbery rules said NO aftermarket heads. This was to reduce the cost of racing. After this rule was eliminated, we went to the aftermarket and found the these heads limited RPN power. I think the stock heads have some class. Gramps

05-18-2023, 08:24 AM	#22
Ziggster Senior Member Join Date: Aug 2018 Location: Ottawa, ON Posts: 857	Re: Safe Way to Check Valve-Head Clearance? Thanks. I’m just a novice, but it is websites like this and folks like you that are willing to share their knowledge that has made this an incredible journey. I agree that raising the CR will be important in raising hp. I was actually surprised to see the sparkplug indentation over the exhaust valve. You certainly wouldn’t expect that looking at the head. I think with my setup (0.060” with the stk 3.75” stroke, and the C7RA stk heads), my CR is a measly 7.14. Good enough for my purposes, but certainly not where you want it to be if more power is your goal.

05-18-2023, 07:07 PM	#24
Jack E/NJ Senior Member Join Date: May 2010 Posts: 2,173	Re: Safe Way to Check Valve-Head Clearance? Ol'Ron>>>angle milling is pretty common today>>> Still worry a bit about studs & bolts without enlarging the holes. I'd rather mill flat & install an angled gasket with an angle of my choosing. 8^)

05-20-2023, 01:28 PM	#26
Bored&Stroked Senior Member Join Date: Jan 2011 Location: Central Ohio Posts: 5,073	Re: Safe Way to Check Valve-Head Clearance? Sponsored Links (Register now to hide all advertisements) One thing to note on the valve clearance: You need to check BOTH sides of the engine. Due to the different valve angles (side to side), the valves on the driver's side are usually about .040 or so higher than the passenger's side. The area you are most concerned about is all the way at the top. *Piston to head clearance:* Given that you're at .073 or so, if it was my engine, I'd have the heads shaved to reduce the clearance to 0.045 (minimum for all areas over the piston crown). This is the final quench dimension - with the head gasket in place. *Valve to Head Clearance:* As you noted, due to the valve angle, they are closest to the head at the very tops. So, if you mill the heads .030, then depending on your final measurements, you may need to do the manual clearance work on the heads for valve clearances at the top of the chambers. The amount you have to clearance will usually be different on one head versus the other (again, due to valve angles the valve heights are different as they relate to the deck). *Manual Head Clearance Work - for Tops of Valves:* I'd use a carbide tool to rework the TOPs of the chambers (the eyebrow area) to give myself about .060 over the tops of the valves (to the head). If you need any examples of the type of bits I use, just ask. I can't remember if your heads are aluminum or cast-iron (while writing this), so the types of rotary files/bits to use will differ depending on the head material.