All Small Six Early 1969 1.5" intake bore log head vs mid 1969 1.75 intake bore log head

[78_200_C4]

Were the early 1969 1.5" intake bore heads small log heads?
Were the mid year 1.75" intake bore heads large log heads?
I have read that the early 1969 log head engines used a smaller base YF carb. and an air cleaner with a smaller throat.

 

[mustang6]

I don’t remember ever seeing a 1969 head with the 1.5” intake bore, but since every other intake with a 1.5” bore is a small log and every 1.75” intake bore is a large log, I’m pretty sure that 1969 head with the 1.5” bore would be a small log.

Also note that the large log heads had different intake shapes- there is the flat top intake, the hex shaped intake, and (on the later heads) the flat top intake with emissions bungs. The differences matter if you are trying to machine the top and install multiple carbs. While the 200/250 shared open combustion chamber heads, the 170 heads (both small and large log) had smaller closed combustion chambers that supposedly flowed better and didn’t require as much milling to support higher compression on a 200. I’m running a milled large log 170 head (DODE-A) head on a 200, patterned after this article Six-Cylinder Performance & Economy Guide.

 

[bmbm40]

I see on page 7 in the Handbook that:
65-69 200 1100 cc manifold volume
69-74 200/250 flat 1240 cc manifold volume
77-80 200/250 flat 1345 cc manifold volume
And also states that the C9DE - M has 1.75" throttle bore and a flat-topped log and that early 69 heads, C9DE - C,F,J and J casting are smaller 1.5" throttle bore.
So it appears that the later 69 heads were large log compared to the early 69 (1240 cc vs 1100 cc). Then in 77 went to 1345 cc so that must be the really large flat log heads.
At least that is how I interpret it.

 

[78_200_C4]

Was there a 1969 1.5" intake bore 250 head ( C9DE-C,F,J,K) or is that just another mistake?

 

[bmbm40]

Not sure. Can't determine based on information in the Handbook. This is where Bubba could have helped.

 

[bmbm40]

From the archive this shows 69-71 250 having 1240 cc log which is a flat topped log and generally considered a large log I believe.​

SMALL SIX SPECS - 144/170/200/250ci​

General Specs

YEAR	CI	Chamber	Intake	Exhaust	Log CC	Adv HP	Adv TQ
60-64	144	44-51	1.467	1.266	850	90	138
61-65	170	48-53	1.522	1.266	890	105	158
65-72	170	48-53	1.649	1.380	890	105	158
65-69	200	51-53	1.649	1.380	1100	120	190
69-71	200	62	1.649	1.380	1240	120	190
72-74	200	62	1.649	1.380	1240	85	154
77-80	200	62	1.750	1.380	1345	85	154
69-71	250	62	1.649	1.380	1240	155	240
72-74	250	62	1.649	1.380	1240	99	184
77-80	250	62	1.750	1.380	1345	99	184
80-up	250	62	1.750	1.380	1420	99	184
AU only	221	62	1.649	1.380	1345	UNK	UNK

Further, this is a tag from the archive indicating production in December 68 for the 250 although not sure how this helps:

Below is an example of the tags used on engines from 64 on. This is the tag from a 1969 250ci engine. They are quite similar to those found on carbs, rear ends and transmissions. They are usually quite accurate, and were normally installed on one of the coil bracket bolts. Unfortunately they are commonly lost or left off after a rebuild.

- 250 is the displacement of the engine.

- 69 is the model year of the engine.

- 1 is the change level.

- 8-L is the year & month produced (68-Dec).

- K45-S is the engine code number.

The engine code number & change level were intended to assist engine shops when they ordered parts. In actual practice very few paid any attention to these numbers, as they only served to complicate the ordering process. Therefore we will not discuss them in greater detail.

 

[bmbm40]

OK now this shows the casting id for the 69-74 250 head as C90E-M 1.75" bore only. Yet the Head ID page you provided states that C9DE-C,F,J,K head casting id for 1969, all engines including 250 is 1.5" bore. Not sure what to make of all this.

Year	Size	Block	Head	Crank	Notes
60-64	144ci	????	????	????
60-64	170ci	C0DE-C4DE	????	????
1965	200ci	C5DE-H	C5DE-B, C6DE-A	1H	4 Bolt Bell
66-67	200ci	C6DE-A	C6DE-A, C7DE-A	1H	6 Bolt Bell
68-69	200ci	C8DE-8	C6DE-A / C8DE-B C9DE-R / C9DE-M	1H	6 Bolt Bell
70-74	200ci	????	????	????	6 Bolt Bell
75-80	200ci	D8BE-GE E1BE-FA	D5DE-BA	1H	6 Bolt Bell
81-83	200ci	E1BE-BB	E0BE-BB E1BE-CC	3H	Big Bell
69-74	250ci	C9DE-B D2DE-AA	C9OE-M	2H	SBF Bell
75-80	250ci	D8BE-JA / 8DE-CC D7DE-CA /D6DE-CA D5DE-AA	E0BE-BB / D5DE-BA D7BE-AB / D3BE-AA D8BE-BA / C9OE-M	3HA	SBF Bell

 

[78_200_C4]

"In 1969 the factory made a running change in the cylinder heads. The carb bore was increased from 1.5" to 1.75".
C9DE-6090-C,F,J, and K casting numbers are the smaller 1.50" carb bore. The C9DE-6090-M has the 1.75" throttle bore and a flat-topped log manifold."
The Ford Falcon Six Cylinder Handbook page 7 Cylinder Heads

CZLN6​

Sep 14, 2004

 

[AKBronco]

All,

Any reason to steer away from the 81-83 head years? Falcon performance book lists the 80 mustang year as "Undesirable smog fitting head" but does this also apply to 81-83 as well? How does the smog impact performance if it is deleted? I do not plan to mill it down to accept anything but would plug any holes if necessary. Thanks in advance.

 

[bmbm40]

That applies to the 80 head only. I contacted Dave S about that and he was going to make that clearer in the next revision of the Handbook.

 

[TrickSix]

I have read that the early 1969 log head engines used a smaller base YF carb. and an air cleaner with a smaller throat.

For what it's worth - I have an 1101 carb supposedly off of a late 1969 Mustang with a 250. Air cleaners that fit on that 1101 will fit on an 1100 as well, so they must have the same size throat. That doesn't mean Ford never made an even smaller opening version though, but I wonder why they would.