Cylinder Head Identification 170 vs 200

ags290

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I am finally taking my replacement cylinder head to the machine shop for an inspection and freshen up. I pulled out the Performance Handbook to go over everything I wanted to get done and came across a question.

How can I tell if the head is from a 170 or 200? The casting number is C7DE-6090-A. In looking at the chart on page 7 of the handbook, the 65-70 170 head and the 65-69 200 head have the same size valves, and the combustion chamber volumes fall within spec of one another. The difference is in the intake log volume if I am understanding the chart. Is this correct?

The head that I am replacing is a C4DE so it would have the smaller valves correct?

I am planning on having the three angle valve job with the 30 degree back cut on the intake valves done as well as milling the head to compensate for the thicker head gasket. What else am I missing?

I has been a long time of saving my pennies to get to the machine shop so I want to make sure that I get it right.

Thanks,

Kevin
 

CZLN6

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Howdy Back Kevin:

Yup, you've got it on IDing. But at least do a visual comparison of the two heads. There is a better than even chance that the C4xx casting will have the larger volume log.

And Yup, you've got the big three covered in machining. You might want to consider having the carb hole drilled out to the later 1.75" diameter and rounding the edges of the "T" at the bottom of the hole where it transitions to the logs in each direction. The incoming charge likes to follow a rounded edge. a sharp edges will cause the charge to tumble. You don't need to worry about turbulence to keep the gas in suspension in the new charge. There will be more than enough turbulence still.

You may want to spend a little time smoothing the combustion chambers. A smooth surface in the chambers helps to reflect heat and reduces hot spots to prevent pre-ignition.

How much are you planning to mill the head? What carb? Ignition? exhaust? are you using.

Good luck and keep us posted on your choices and progress.

Adios, David
 

ags290

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David,

Thank you for the confirmation on the ID. The C4xx head that is currently on the car appears to have the smaller intake log but it is just a visual inspection. I have not removed it yet. I bought a replacement from a member on the forum that is supposed to have been freshly rebuilt with very low miles. It is the C7DE head that I am taking to the machine shop for tear down and inspection. I am not sure how much has been milled previously, so the plan was to cc the combustion chambers and mill accordingly to end up with a volume of as close to 50 cc's as I can get. I would like to end up with a compression ratio of 8.5 to 9.0 to 1.

As for your questions:

1) The carburetor is a Motorcraft service replacement for the Autolite 1100. It has a fresh rebuild on it with parts from Mikes Carburetor Parts. It is the smaller bore and I need to reuse it. It has the spark control valve.

2) The ignition system is still the Ford Load-O-Matic. I have installed a Petronix's pickup in place of the points and condensor and have removed the resistor wire and have a 12v coil. I have a new set of Motorcraft spark plug wires and Autolight 46 spark plugs to install with the rebuild on the head.

3) The exhaust is the stock Ford cast iron manifold with a single pipe.

The C7DE head that I purchased has the exhaust port divider installed. It was tack welded in at 3 points across the top and at the bottom of the "T" at the bottom. If I am planning on keeping the stock cast iron manifold should I remove it? Or should I just keep it in place and have the machine shop just true the mating surface up with a light pass?

Thanks for the Help,

Kevin
 

CZLN6

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Howdy Back Kevin:

All sounds good. I should have asked you what you will be using this engine for? Any down-the-road plans for more mods?

The installed divider is fine, actually a slight improvement. Do you have the C7xx exhaust manifold? If so, use it. Which ever, spend a little time opening up the 2" outlet. Get a short piece of 2" exhaust pipe to stick into the outlet like a firewall fitting. You will notice excess casting protruding over the tip of the pipe. This extra casting should be ground away to provide a full 2" outlet. At some point, in the future you may want to upgrade to a 2" exhaust system with a turbo type muffler.

I'd sure be leaning toward a 9:1 CR.

When assembling use .030" valve spring shims to tighten spring pressure.

I am not a fan of the Holley #1940 service replacement carb but some on this forum have used them successfully. On the LoM distributor, be sure to check the advance mechanism to make sure it is working as designed. Set the initial advance a 5 more degrees above your stock specs.

I hope that helps you. Keep us posted on your progress.

Adios, David
 

ags290

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Howdy All,

Got a call back from the machine shop today. The head magna fluxed out OK so I am proceeding with the rebuild. From the best I can tell it is a 66-68 Falcon or Comet head, casting number C7DE-6090-A. I had already purchased new valves, so we are going to install them all. ( There was stem wear on 2 of the intakes and 3 of the exhausts). The valve guides all check out to be within spec. I had also bought new SBF valve springs so we will install those as well with .030 shims.

Machine Work:
1) Replace exhaust valve seats with hardened ones for today's gas.
2) Mill the head .020" to compensate for the thicker head gasket and cc the chambers to see if additional material needs to be removed.
3) Mill the exhaust manifold mating surface to make sure it is true.
4) Cut the valve guides to accept the positive lock valve seals.
5) 3 angle valve job and 30 degree back cut on the intake valves
6) Smooth out the lower edge of the intake below the carb where the charge enters the log.

My new questions are:
1) Which rocker shaft setup should I use? I have a new reman non adjustable shaft and arms assembly that I would need to buy push rods for, or I can reuse the adjustable setup that I currently have on the car.
2) Which head gasket should I use? I have a Felpro 7916 PT-1 gasket only and a Ford C90Z-6079-A upper end set.

The car is just a pleasure cruiser/daily driver my son and I built for him to drive to High School, he is away at College now and the car has stayed home with me. I don't foresee any performance modifications in the future, but I certainly don't want to give up and performance in the process.

As Always, Thanks for the Help,

Kevin
 

Matthew68

Well-known member
CZLN6":2skfxd0y said:
Howdy Back Kevin:

Yup, you've got it on IDing. But at least do a visual comparison of the two heads. There is a better than even chance that the C4xx casting will have the larger volume log.

And Yup, you've got the big three covered in machining. You might want to consider having the carb hole drilled out to the later 1.75" diameter and rounding the edges of the "T" at the bottom of the hole where it transitions to the logs in each direction. The incoming charge likes to follow a rounded edge. a sharp edges will cause the charge to tumble. You don't need to worry about turbulence to keep the gas in suspension in the new charge. There will be more than enough turbulence still.

You may want to spend a little time smoothing the combustion chambers. A smooth surface in the chambers helps to reflect heat and reduces hot spots to prevent pre-ignition.

How much are you planning to mill the head? What carb? Ignition? exhaust? are you using.

Good luck and keep us posted on your choices and progress.

Adios, David

Hi David,

I realize this is an old thread, but I too have this head casting ID (C7DE-6090-A). I have a 1968 Mustang, the head and block are original to the best of my knowledge. Is my head a 170 head or a 200 head? I have paperwork from a previous owner that says "head rebuilt" in the 80s, but it doesn't say it it was swapped out. I have a 200 block, with 5 freeze plugs. According to the Falcon Handbook, this head casting # is from a 66-68 Falcon/Comet 170ci. However, on the Classic Inlines Tech Archive, that head is listed as a 200ci.

Which is correct? If I do indeed have a 170ci head on my 200ci block, will this cause me any issues? I'm planning for a 77-79 head for a 2V conversion, but just wanting to know for the immediate if there's anything I should be aware of.

Cheers,
Matthew
 

CZLN6

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Howdy Back:

Kevin- I'd use the adjustable rocker arms. Make sure to disassemble and clean the inside of the shaft.

On the head gasket, I don't know what make FoMoCo is using in their kits, but which ever you choose measure the thickness and use that as your guide in deciding how much to mill the head.

Matt- This head was used on both 170 and 200 engines in that model year(s). To the best of my ability to decern a difference, there is no difference.

Adios, David
 

bmbm40

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Interesting to read about your head mods and would like to hear your driving impressions when all said and done. Just food for thought but the Falcon Handbook mentions an 1101 from early 60's sixes with the SCV feature with 210 cfm and 1.69 throttle bore so could be a nice compliment to your head work for some more performance. Don't know the cfm of your current Holley 1940.
Good luck
 

chad

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here's frm X over on 4-eyed pride (he's havin trouble login on here). As usual I (he) gives extra info but U should B able 2 wade thru it easily:

"...Holleys 1904,1908,1909 before the Autolite replacement Holley 1940, and well before the 1978 to 1983 200 3.3 Holley 1946

1952 = 1904 215/223/262 and 1960=144. 130/150/170cfm for the 1904,
1960 late 1908 144 and 170, 135/150cfm for the 1908,
Early Holley 1909 series was rated at 170 CFM and 125/150cfm for the small 1909.
1962 1909 was 170

Autolite 1100 Sizes and Applications
1100 and 1101 Autolite 1-bbl 1.00-, 1.10-, and 1.20-inches. Mustangs had either 1.10- or 1.20-inch depending on model year and configuration. Basic bore size was 17/16-inches.
1.00 Venturi(120 CFM): 144 ThriftPower Six, 1.4375 Throttle, 84 to 90 hp
1.10 Venturi(150 CFM): 170 ThriftPower Six, 1.4375 Throttle,105 or 101 hp, then derated 68-69 200's
1.20 Venturi(185 CFM): 200, 250 Six, 1.4375 Throttle
The 1101 TB measures 1 11/16". Venturi measure 1.29" It is rated at 210 cfm. 1.6875" throttle 1969 only 250

The Carter YF first saw use on California emissions 170 and 200ci sixes in 1967. In '68-'69, only 170 and 240ci sixes got the Carter YF, which means you will never see one on a Mustang .
YFs came in 150, 187, 193,195 and 200-cfm sizes.
YFs came in 150 cfm 170 CID 1970 Maverick
YFs came in 187cfm in 1970 200 cid Mavericks
YFs came in 193, or 200 cfm, 195 cfm in 1975 -1979 L-code 250'S
1970-1973 250 Carter RBS L-code Only one size-215 cfm-was produced

Last ones are the ones to target at car yards."
 
I am finally taking my replacement cylinder head to the machine shop for an inspection and freshen up. I pulled out the Performance Handbook to go over everything I wanted to get done and came across a question.

How can I tell if the head is from a 170 or 200? The casting number is C7DE-6090-A. In looking at the chart on page 7 of the handbook, the 65-70 170 head and the 65-69 200 head have the same size valves, and the combustion chamber volumes fall within spec of one another. The difference is in the intake log volume if I am understanding the chart. Is this correct?

The head that I am replacing is a C4DE so it would have the smaller valves correct?

I am planning on having the three angle valve job with the 30 degree back cut on the intake valves done as well as milling the head to compensate for the thicker head gasket. What else am I missing?

I has been a long time of saving my pennies to get to the machine shop so I want to make sure that I get it right.

Thanks,

Kevin
I thought the 200 heads had D shaped chambers and 170’s had kidney shaped.
 

chad

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3 y/o thread: could add that I believe some very early 2.8s hada shape like that U mention, rare to find. Also w/same certainty - all heads fit all blocks (no thanks tho).
(& "hope he cc the head B4 final mill pass")
 
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