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Discussion Starter #1 (Edited)
I have a 1966 mustang, and I am looking to replace a few things on it. I need to figure out my engine size. I know that the numbers from the head and on the block will tell you the year but not much more than that. I know C stands for 1960, and the next number stands for the exact year. My problem is that in one place it says C8 which would mean 1968, but in the other place it says C9 which would mean 1969. These years came with different types of engines. Anyone got any ideas of the size or what type of engine this is??
749620
749621
mustang engine 2.jpg mustang engine.jpg
 

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It looks like your '66 has an engine out of a '69 or later. The C8 and C9 only mean the first year that the particular part was used. So a 200 cu in 6 out of a late 70's Fairmont may very well have a 1968 exhaust manifold if that manifold was never updated.
It is obviously a 6 cylinder so I am going to say it's a 200.
 

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Magnus is correct. 5 freeze plugs = 200 cid
mid '64 on up had 7 main bearings. virtually indestructible.
Fifth digit on the Vin would be a "T"
3 water pump bolts were used on the 144, 170, and 200. 4 bolts on the 250 cid.
 

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Ford discontinued the 170 in August, 1964 and the 144 was discontinued prior to that. The 250 is "taller" than the 200 so extreme measures are required to fit it underneath the hood of a '65-'68 Mustang. I can say with about 90% probability you have a '69 or later 200. If you can find the casting or engineering number (it's NOT a part number) that is cast into the side of the block and then find the 3 or 4 character date code close by we can narrow it down closer.
 

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OK, your block casting/engineering code is D8BE-6015-GA which tells us it was a 1978 redesign of the original part. As I recall the Fairmont continued to use the 200 up through the late 70's or early 80's. Somewhere near that casting number is a date code that will be in the format of NLNN- numeral, letter, numeral (numeral). Since the engineering number is D8 the first numeral will be a 7 (1977), 8 (1978), 9 (1979), 0 (1980), etc. The letter will be A-M for Jan-Dec with I not used. The last numeral (numerals) will be 1-31 for the day of the month.
 

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Discussion Starter #10 (Edited)
I think I found the number you were talking about. It looks like it is 7C22, but I had a hard time trying to see. Here is the picture. I hope this helps to find out what engine it is.
749651
 

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That looks like 7C22 which would be March 22, 1977 but that is strange. The engineering code of D8 means it was designed for the 1978 model year and March of 1977 was still the 1977 model year. 1978 model year production would have begun in August of 1977. Maybe that 7 is a 9? It doesn't really matter as it's a late 70's 200.
I see that it does not have a Duraspark II distributor. Whomever put it in your Mustang must have put the original '66 distributor in it.
 

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Here's my two cents - take it for what it's worth.

Your carb is a Holley 1940. It is an acceptable replacement for the original Autolite 1100. Some people don't like them. I have one and don't have any big issues with it. I don't think there is a need to change it unless there are some underlying problems. The hose that goes to you heater should run through the base of the carb. The place it should attach is covered in that teal colored duct tape. The hose running to the heater (it's running close to parallel with the exhaust manifold) has been spliced. The front of the hose goes into the carb and the back should attach to the back of the carb - straight back from the inlet.

I'm not sure why a prior owner would bypass the carb unless there was some kind of problem.

The carb also has a spark control valve (SCV), which would match up with an original '66 distributor as awhtx suggests.

Good luck.
 

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The heat source in the base of the carb is only needed if you're driving your Mustang in cold weather. In warm weather it reduces efficiency and power. If it is routed across your choke housing, well, that would be a different story. But my, and I think most, of these sixes get their choke heat from the exhaust manifold. I haven't run my heater hose through the carb spacer for quite a while now, I even switched to a version that never had the tube. I haven't waited for all these pictures to load yet, so I'm not sure what you have, but in 1969 there was a running change made to the six cylinder heads. Probably the most noticed change is the carburetor inlet, increasing from 1.5" to 1.75", and the mounting studs moving a little further apart. Something to pay attention to when carb swapping. If you have the spacer with the water tube, you may have the earlier small version, I don't think I've seen the big hole style with a water tube.
 

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Went and did some stuff, waited for pics to load. "C9DE-6090-J" code means you got the early '69 head, with the smaller carb bore. "M" instead of "J" is the later head.
 

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Discussion Starter #16
Thankyou a ton for all the help. I had one more question. I talked to the mechanic and he attempted to rebuild my carb, but said that it was to messed up to fix again. If anyone knows the carb that I need to get please send me a link. Thanks a ton
 

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Well, as alluded to earlier in this thread, your distributor may limit your carb choices, as some are designed to work as a set. You need to first determine for sure what distributor you have, and then decide if you want to keep or change it.
 

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Discussion Starter #18
with my current distributor does anyone know of a carb that would work with it that I could trust?? aftermarket is good with me I jus need to find a carb that would work.
 

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From what I see in this thread, you've got a real dogs breakfast of an engine. The head is early '69, the block late 70's, that valve cover looks like it could be from '66, so who knows what you have for a distributor. Pop the cap off and take a picture. If it's the original Load-O-Matic you need a carb with the spark control valve, if it's a later distributor you do not. The Load-O-Matic system has its fans, but some users think it's a load alright, but not of distributor parts. (Sorry Tony) I hope you're not in a hurry to get this done, but can take some time to do the research you need to arrive at an informed decision that is right for you and your future plans for this car.
 

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Discussion Starter #20
Hey guys thanks for all the help.
Just some info for you. I just turned 17 and my dad has had this 1966 mustang convertible in the shed for a really long time. My dad is giving it to me, but I just need to get it running.
With yalls help and my local mechanic we got the car running but said the carb needed to be replaced. Talking with him today he said we could clean the fuel line easily, but we need to buy a new gas tank and carb. Right now I know it is a holley 1940 carb with a spark control valve. The engine is a 200 ci, 5 freeze plugs, the distributor is the original distributor. We replaced the points and plugs, and we replaced the fuel filter. The mechanic stated that we could get any aftermarket or refurbished carb. I was just wondering if there was a certain one yall know that will work well, or a brand and product that would be good?
Im hoping to get the car running for the summer. If iI get this running im hoping to find a 69 fastback to be my first car that I can build in full. Thankyou for all yalls help!!!
 
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