Head Modification Questions

6

65_Stang_170

Well-known member
Howdy!

I have a '69 M-code head sitting in my garage awaiting modification, and have a couple questions:

1) With the large flat intake on this head, will there be low spots that need "filled" like the hex heads when doing the 2v conversion? Example photos from tech archive below...
2) If I upgraded to the 1.75" intake valves, will that require modification? Worth it?
-Does the 1.75" refer to width? (I'm still trying to learn about the internals of an engine)

-Usage will be mostly around town stuff with the occasional long highway trip
-I'm planning on upgrading my cam while head is off in addition to the mainstays (valve job/back cut, etc...)

Thanks all!
 

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Howdy 65 Stang:

Q- With the large flat intake on this head, will there be low spots that need "filled" like the hex heads when doing the 2v conversion?
A- Probably not. Less filling for sure, if needed. It will also depend on which 2V carb you use and which adapter. Also, head castings vary on internal dimensions.

Q- If I upgraded to the 1.75" intake valves, will that require modification?
A- Probably not, but check carefully to make sure the 1.75" intake valves clear the smaller bore of your 170. Also be sure to use a 200/250 head gasket on assembly.

Q- Worth it?
A- I would say yes. How much? Well that depends on other factors in your engine build.
In addition to larger valves be sure to add a back-cut to the intake valve regardless of which intake valves you use. FYI, 1.75" intake valves became standard from the Ford factory on all six cylinder engines in the early 70s. If FoMoCo thought they were worth the added expense that is a good indication of their worth.

Q- Does the 1.75" refer to width?
A- Yes, the width across the face of the valve head.

I'll be interested to hear your other plans along with a new cam. Compression ratio? cam specifications? what rear end gear ratio?

I'm enjoying your project and planning. Keep us informed.

Adios, David
 
CZLN6":195ipbhd said:
Howdy 65 Stang:

Q- With the large flat intake on this head, will there be low spots that need "filled" like the hex heads when doing the 2v conversion?
A- Probably not. Less filling for sure, if needed. It will also depend on which 2V carb you use and which adapter. Also, head castings vary on internal dimensions.

Q- If I upgraded to the 1.75" intake valves, will that require modification?
A- Probably not, but check carefully to make sure the 1.75" intake valves clear the smaller bore of your 170. Also be sure to use a 200/250 head gasket on assembly.

Q- Worth it?
A- I would say yes. How much? Well that depends on other factors in your engine build.
In addition to larger valves be sure to add a back-cut to the intake valve regardless of which intake valves you use. FYI, 1.75" intake valves became standard from the Ford factory on all six cylinder engines in the early 70s. If FoMoCo thought they were worth the added expense that is a good indication of their worth.

Q- Does the 1.75" refer to width?
A- Yes, the width across the face of the valve head.

I'll be interested to hear your other plans along with a new cam. Compression ratio? cam specifications? what rear end gear ratio?

I'm enjoying your project and planning. Keep us informed.

Adios, David
Click to expand...

David, as always, thanks for the info.

It's hard to pick a carb based on all of the differing opinions and information. It seems like they all get you to pretty much the same end though. I have been leaning toward the Weber 32/36. I do like the varying CFMs of the Autolite 2100 and being able to match it to what the specific engine needs... But the availability of parts/jets/etc, based on what I have read, aren't the easiest to acquire?

I'm still digging into what the different cam specs mean, and how they affect idle/power/etc, so more to follow. Same with the compression ratio. I want to run pump gas obviously, but I don't think I care whether it's regular or premium.

I have 3.20 rear end, and will be putting in a WC T5 once I get back from the middle east. I believe the gears are: 3.35, 1.99, 1.33, 1.00, 0.68. I have 205/70r14 tires. I will also be installing the ebay dual outlet headers (still deciding on dual vs single exhaust though...) when I get back. I will drive it around like that while getting the work done on the head.

-Shawn
 
Howdy Back Shawn:

I like the way you are thinking. Cam selection is critical given your small displacement 170 engine choice. Be sure to investigate input from others that have been down this road.

I personally favor 2100, but I've been collecting them since the seventies when there were millions of small block Ford V8 laying around. There has never been a more easily tuned and maintained carb. The Holley/Webers have been around for awhile too. Many here have/are using them. They are more expensive and a little fussier to get tuned right. The Holley 2300 two barrels came in many sizes too, although a little harder to find in smaller sizes. They are very tunable and parts are available.

Choosing a CR on pump gas is easier. 9 to 9.5:1 is a good goal range given your driving needs. In a smaller diameter bore of a 170 ping, or knock is less of a concern. You can mill your "M" head up to .090" to achieve your CR goal. Milling that head is the cheapest HP and torque you can buy. And with a cam upgrade more CR is a good idea.

I really like the trans and gearing plan. You will too. Good luck and keep it coming.

Adios, David
 
"...ebay headers…"
many of us use Matt's at vintage inlines (a member here).
We believe they're the same as the 'speed daddy' (crossh).wrenced screwdriver/
U can C the design in the above 'tech archive' at the big blue box (crossed screwdriver/wrench).
 
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