Info needed with my 71 Mach1

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Dirconmach1

Well-known member
Joined
Nov 14, 2019
Messages
76
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Location
Fort Valley,Virginia
My Car
1971 Mach 1 351 Cleveland, 4 barrel, ram air, 4 speed, factory a/c, 77 k original miles in bright red with black.

Drive it like you stole it!
There seems to be a lot of info out there going back and forth as to the type of motor in my Mach1. Vin is 1F05M224463. The door tag is dated 7/71. From what I read, in may of 71 they changed the 351 Cleveland to open chambered heads and called it the 351 cj motor. The guy I got this from swears it’s a high compression engine. But the cj where 9.0 to 1 compression. Then I read there were Q codes this year that came out late in 71. I also saw contradicting info that stated only M code was used that year. This is a 77k car that has never had the engine out. I know the carburetor is wrong( Hollie). I’m trying to install the correct type. It’s supposed to be a Autolite 4300, or 4300D. The other info on the car is 351 C with ram air, 4 speed with factory A/C. What’s your thoughts on this gray area? Thanks for any help you can give. Forgot to mention, I’m a virgin to the 71 To 73 era. Still sporting my 69 convertible. Been a ford guy for the last 40+ years. This is my 6th stang.This 71 gave me a cubby when I saw it. Had to get it for my soon retirement. Thanks

 
Based on my limited knowledge, on the head in one corner you should see a 4 with a dot or no dot. The info I have says:

4 no dot - data so far says "closed chamber 1970 model" - maybe very early 71


no need to look too much further.


 


4 dot - pull the valve cover and check the date code - if it says 1F** or earlier, data says it will be closed chamber.


 


4 dot - date code later than mid year 71 date code, you'll have to confirm the casting number to guarantee closed chamber vs. open.


 


4 dot - date code later than 1972 date code 2***, probably open chamber unless some rare service head is in the mix.


The M code came out before May 71 and was 10.7:1 compression and 285hp. The Q code was after May 71 and was less compression and 280hp.

You would probably need to check the casting nbr for after May 71 as mentioned above.

You can also verify if it really is the engine for the car by crawling underneath and looking for the vin number on the back of the engine block on the drivers side.

 
Your VIN says you have an M code engine (5th digit), and M codes in 1971 were the closed chamber heads. The CJs were Q code engines in 1971, and later. Because your car has a Holley carburetor it likely is a square bore carburetor, which was used on M codes. Q codes used the spread bore 4300D carburetor. The information in these threads should help you.

https://www.7173mustangs.com/thread-ford-code-numbers?pid=347340#pid347340

https://www.7173mustangs.com/thread-casting-numbers-and-engine-codes?pid=203996#pid203996

To check if it is the original block you'll need to look at the partial VIN on the back of the block, driver's side, right below the head gasket. You'll need a mirror or cell phone picture to see it.

 
Thanks steve O-71 and Don C, in the age of fake news, it’s hard to believe anything is correct that you read. I would rather seek info from the guys that live and breathe the cars everyday. I will look tomorrow for the numbers. Thanks again

Dave

 
No grey area here, you have an M-code car and if the engine is original as you stated, then it's the M-code high compression engine. If your car came factory with the Q-code engine, then you'd have a 1F05Qxxxx VIN tag. M & Q code were produced concurrently until the end of the '71 model year production.

Overall, as a package, the 351CJ was a much better engine as it came with a long duration performance cam, dual point ignition, proper rear gears and a slippy converter with the automatic. Ford totally pooched the M-code powertrain setups.

FWIW, save yourself the hassle and keep the Holley over a Motorcraft 4300. The 4300 had lots of issues and if you get a crap one, it'll always be crap.

 
No grey area here, you have an M-code car and if the engine is original as you stated, then it's the M-code high compression engine. If your car came factory with the Q-code engine, then you'd have a 1F05Qxxxx VIN tag. M & Q code were produced concurrently until the end of the '71 model year production.

Overall, as a package, the 351CJ was a much better engine as it came with a long duration performance cam, dual point ignition, proper rear gears and a slippy converter with the automatic. Ford totally pooched the M-code powertrain setups.

FWIW, save yourself the hassle and keep the Holley over a Motorcraft 4300. The 4300 had lots of issues and if you get a crap one, it'll always be crap.
 
No grey area here, you have an M-code car and if the engine is original as you stated, then it's the M-code high compression engine. If your car came factory with the Q-code engine, then you'd have a 1F05Qxxxx VIN tag. M & Q code were produced concurrently until the end of the '71 model year production.

Overall, as a package, the 351CJ was a much better engine as it came with a long duration performance cam, dual point ignition, proper rear gears and a slippy converter with the automatic. Ford totally pooched the M-code powertrain setups.

FWIW, save yourself the hassle and keep the Holley over a Motorcraft 4300. The 4300 had lots of issues and if you get a crap one, it'll always be crap.
The July door tag I clear. I read somewhere that all V4 351 Cleveland’s in mustangs used only  the M code for 1971, except boss 351. It also stated the Q code was first used in 1972. I plan on doing a compression test soon. That will clear things up without having to pull a lot apart.

 
Ford does model changes during the July 4th. holidays so your car was made at the end of the 1971 model run. Like stated your M designation in VIN tells what you should have. But never say never with Ford. Check the casting numbers and dates and if you ever pull them will tell the tale. 

You should order a Marti Report you can get the cheap one for $18.00 and will be pretty quick reply. It will tell everything that is on your car when original. If you pull the interior out to do some work look for the build sheet, might be stuffed in rear seat cushion, under carpet, under sound deadening or even stuffed int seat riser. 

When they do model changes parts get used up and parts get substituted if they run out of what the normal is. They do not shut the line down until the last car is built. 

Even the last car is deceiving. Ford assigns a VIN# when an order is received. Your car might get built earlier or later out of the VIN# sequence while waiting for optional parts to show up for the actual build. The Marti will tell you all those dates. 

One of our club members has the last Fox Body Mustang built down the line but was not the last VIN# assigned. Confusing for sure but happens everyday. 

This is one of the best references we have on Ford casting and part numbers. Like I said there is always exceptions to every rule. 

http://mustangtek.com/heads/Heads.html

 
Ford does model changes during the July 4th. holidays so your car was made at the end of the 1971 model run. Like stated your M designation in VIN tells what you should have. But never say never with Ford. Check the casting numbers and dates and if you ever pull them will tell the tale. 

You should order a Marti Report you can get the cheap one for $18.00 and will be pretty quick reply. It will tell everything that is on your car when original. If you pull the interior out to do some work look for the build sheet, might be stuffed in rear seat cushion, under carpet, under sound deadening or even stuffed int seat riser. 

When they do model changes parts get used up and parts get substituted if they run out of what the normal is. They do not shut the line down until the last car is built. 

Even the last car is deceiving. Ford assigns a VIN# when an order is received. Your car might get built earlier or later out of the VIN# sequence while waiting for optional parts to show up for the actual build. The Marti will tell you all those dates. 

One of our club members has the last Fox Body Mustang built down the line but was not the last VIN# assigned. Confusing for sure but happens everyday. 

This is one of the best references we have on Ford casting and part numbers. Like I said there is always exceptions to every rule. 

http://mustangtek.com/heads/Heads.html
Great link, save to my desk top. Thanks

 
First, hello and welcome to the Forum.

I could have missed it, but did you go to "Introductions" and introduce yourself... with pictures of the car?? We LOVE pictures!!

I own a Feb 71 M code Mach 1. From what others have told you, the car ought to have Closed Cambered heads, but to be sure, there are the casting numbers to go by, but some are not easy to get to without stripping the intake off. For some 'reason' Ford decided it would be a good idea to cast the head codes UNDER the intake ports. Here are a couple of pictures that might help.

I don't have a lot of time right now, so I may expand on this later.

Geoff.



Block number and date code.



Casting code



Engineering level GA



Not easy to read, but it's 0M4 1970/Dec/04

More later, got to go now.

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Just ordered a Marti report, I plan on pulling the car out of my enclosed car carrier during the long Thanks giving weekend. I will try to locate the number then, I will also be looking for the original build sheet. Thanks

 
Just ordered a Marti report, I plan on pulling the car out of my enclosed car carrier during the long Thanks giving  weekend.  I will try to locate the number then, I will also be looking for the original build sheet. Thanks
 Now I'm back,

here is a pic or two of the build sheets I found in my car. I actually had 3, all in pristine condition. One under the front driver seat and two under the carpet underpad behind the driver seat.

It gets really interesting going through and digging up information on your car. 

Do you have the engine tag? It is a small aluminum tag, 2.5" X 3/4" and if there, will be under the coil hold-down bolt. If your engine has never been "touched", it should, if you're lucky, still be there. Mine was, but I now keep it with my other original documents. Also is the Buck Tag still there? It will be located on a 71/72 on the passenger side in front of the rad support. I was unlucky with this one as it was broken off. These can be replaced from Marti Auto Works.

The partial VIN on the block as described in another post is vital to proving the engine IS the original.

Geoff.



Front one, just the corner showing



One of the two. The other one was laying on top of this one.

 
The block number is a little difficult to see, it's located above/behind the starter on the passenger side.
 Thanks for adding that Don.
I knew you would have if you hadn't been in a hurry :)
….. or it could be my failing memory!!

There's got to be more to add, but I can't think of anything right now. Time for a beer to refresh the mind.

 
A good source for casting and date code info is this website, www.mustangtek.com  I have found it pretty reliable, but like all, not 100% correct.

On my engine, the heads are D1AE-GA. Date code is 0M01 (not 04 as previously mentioned). They are 4 dot (4*) listed as 71 351C Mustang / Torino, 4V with 2.19" intake, 1.71" exhaust, 64cc closed chamber, in port 2.5" x 1.75", ex port 2.00" x 1.74" It shows a Ford number as D1AZ-6049-B, not sure if that is correct though.

If you can, please list your intake ID info as it all helps.

What Holley carb is fitted and dose it have a factory distributor, points or upgrade to electronic. This is for future help we all know you're going to need.

These can be fun or frustrating for sure, so enjoy your new toy.

Geoff.

 
The July door tag I clear. I read somewhere that all V4 351 Cleveland’s in mustangs used only  the M code for 1971, except boss 351. It also stated the Q code was first used in 1972. I plan on doing a compression test soon. That will clear things up without having to pull a lot apart.
Lots of bad info out there from people that heard from a guy that heard from another guy that heard from another guy - ad nauseum. Lots of bad info in magazines and books as well. If I find less than five errors in an article on a 71-73 Mustang, I'm actually sort of impressed.

M-code ran the full '71 model year, your July '71 built M-code car supports that. There are others here with post-May '71 model year M-code cars as well.

Compression test won't tell you anything other than the cranking compression of the engine and the general health of the rings and valves.

 
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