Engine Identification

[Sparky]

Good Morning - I am looking for a little help with my 1973 Mach One. The car was originally an H code 2 barrel but has had a 4 barrel swapped in. The heads are 4 barrel as denoted by the 4 cast into them. There is no adjacent little bump so I assume they are closed chamber heads. I have no other information beyond a 2005 appraisal stating the engine is a “351 Cobra Jet” I cannot get any further information as I purchased the car from the previous owners widow after he passed away. Does anyone have any idea where I can find casting numbers on the block to identify it’s year or other data? I will be replacing the oil pan as the drain plug is in very poor shape - it is a universal one and leaks unless extremely tight - I do not trust it and the current pan has been hit a few times as well. Thanks for any help or suggestions!

 

[Sheriff41]

Closed chamber heads were used on 70 and 71 M-code engines. Many people confuse the M-code with the Cobra Jet title. To the best of my knowledge, the 351C Cobra Jet engines all came with open chambered heads. There are many debates over which engine is better.

One of the more knowledgeable members here will let you know where on the lower part of the block the numbers are and what they indicate. The casting numbers I look for are near the starter on the block.

 

[Sparky]

Thank you for the info - car is on a lift so I will look in that area this morning and see what I can find for casting numbers and post them.

 

[Hemikiller]

The factory block in your car would have a D2AE-CA casting, which can be found above the starter. Ford used the same casting for 2V and 4V engines, they were just machined differently depending upon 2 or 4 bolt mains. You'll also want to get the casting date. in order to verify whether or not it's the original block, there will be a partial VIN stamped into the driver's side rear of the block, just below the head. If it's original, it should read 3Fxxxxxx, which is: year (1973) - assembly plant (Dearborn) and the consecutive unit number of your VIN.

Most appraisals aren't worth anything more than the paper they're printed on. The 351-4V Q-code was "technically" the CobraJet engine in '73, Ford just didn't use that term on the Mustang.

The "4" with no "dot" cast into the heads indicates that you have a 99% chance of a set of 1970 M-code closed chamber 4V heads (D0AE-G, M, N or R). These heads are 63cc nominal, vs the 67cc nominal of the 71 M-code head (D1AE-GA).

The dot does not guarantee that the heads are closed chamber, regardless of what people say or what you've read. The initial run of 71 M-code closed chamber heads also had no dot, but it was added in July '70. Some say it indicates a cooling revision. One thing that can be said for certain, is that all open chamber 4V heads will have the dot.

Regarding the oil pan, I'd repair what you have. The aftermarket pans are okay, but the factory pans are top notch. Knock out the dents and use a thick sealing washer on the drain plug.

 

[Sparky]

Good Morning - Thank you for that detailed response as well as the picture. I was told the entire engine was a transplant but who knows. I will look at the casting numbers today and post them once I have them.
Thanks again for the great info!!

 

[Stanglover]

On the heads, you could remove the valve covers and be able to see the date codes. The casting codes unfortunately can't be seen without pulling the intake manifold. However the date codes will give you some idea as to whether they match the block date code.

 

[Tnfastbk]

When you do find numbers here is a good site for information.

https://www.mustangtek.com/FordDecode.html

 

[Sparky]

Hi - I removed the started and the block is D2AE-CA probably no surprise. date code is 3A29 and I will pull a valve cover as soon as I can get some new gaskets. Head has an R in pin punch marks on rear but I am trying to to read the rest of the numbers and will post soon. Thanks All!!

 

[rackerm]

The factory block in your car would have a D2AE-CA casting, which can be found above the starter. Ford used the same casting for 2V and 4V engines, they were just machined differently depending upon 2 or 4 bolt mains. You'll also want to get the casting date. in order to verify whether or not it's the original block, there will be a partial VIN stamped into the driver's side rear of the block, just below the head. If it's original, it should read 3Fxxxxxx, which is: year (1973) - assembly plant (Dearborn) and the consecutive unit number of your VIN.

Most appraisals aren't worth anything more than the paper they're printed on. The 351-4V Q-code was "technically" the CobraJet engine in '73, Ford just didn't use that term on the Mustang.

The "4" with no "dot" cast into the heads indicates that you have a 99% chance of a set of 1970 M-code closed chamber 4V heads (D0AE-G, M, N or R). These heads are 63cc nominal, vs the 67cc nominal of the 71 M-code head (D1AE-GA).

The dot does not guarantee that the heads are closed chamber, regardless of what people say or what you've read. The initial run of 71 M-code closed chamber heads also had no dot, but it was added in July '70. Some say it indicates a cooling revision. One thing that can be said for certain, is that all open chamber 4V heads will have the dot.

Regarding the oil pan, I'd repair what you have. The aftermarket pans are okay, but the factory pans are top notch. Knock out the dents and use a thick sealing washer on the drain plug.

Hi - I removed the started and the block is D2AE-CA probably no surprise. date code is 3A29 and I will pull a valve cover as soon as I can get some new gaskets. Head has an R in pin punch marks on rear but I am trying to to read the rest of the numbers and will post soon. Thanks All!!

Also, look on the front edge of the block on the Passenger side near the water pump and Timing pointer. I found a partial date code there on my 70 Metuchen built car with an M code Cleveland block.

 

[Stanglover]

Hi - I removed the started and the block is D2AE-CA probably no surprise. date code is 3A29 and I will pull a valve cover as soon as I can get some new gaskets. Head has an R in pin punch marks on rear but I am trying to to read the rest of the numbers and will post soon. Thanks All!!

Making progress I see. Jan 29 1973 casting date. Could be a 4 bolt then.
For valve cover gaskets, I like the rubber ones over cork. They can be reused...... sometimes!

 

[Sparky]

Hello - I have attached the block casting number and a picture of the head with an "R" stamped into it as well incase that helps with identification. Thanks

 

[Sparky]

Good Afternoon - Okay now I am confused! Could these be aftermarket pedestal mounted roller (tip only) rockers that were installed by the previous owner? I bought aluminum valve covers with "351 Cleveland" cast into them and they will not sit down onto the head properly I suspect due to the rocker size - any info if anyone has seen this setup would help? date code on head shows "9J20" so I assume 1969 October 20th?

 

[detritusmaximus]

They seem to have an old Crane Cams logo on them, not factory.

 

[Hemikiller]

Those are Competition Cams Magnum roller tip rockers with a Crane Cams stud & guideplate conversion kit.

Some valve covers have oil drippers that need to be removed to work with larger rockers and studs.

The heads are 70 model year 4 barrel closed chamber heads by the casting date.

 

[Sheriff41]

Yep, some CC heads with some work done on 'em. 9J20 = 20 Sept, 1969. Here's one option for the valve covers: https://www.jegs.com/i/B-B/128/63920/10002/-1

 

[Spike Morelli]

Just an observation here.......the rocker arm nuts are installed upside-down,except 3rd from rear, and the exhaust rocker pivot ball, second from the front, in the photo, is broken. Replace stock pivot balls with grooved balls. This was not done by a knowlegeable mechanic. Wait, did someone double-nut those rockers? WTF? If so, fix that, single crimp nut, crimped end UP. Yes, the aftermarket nylon pushrod guides are Crane. The screw-in studs have only the 5/16ths threads going into the un-machined head as stock, and allow adjustability, but should not be used with spring tension above a certain amount. Check to see if any of the rockers are "blueing" around the ball socket area.

 

[Sheriff41]

Amazing what experience and a trained eye detects!

 

[Sparky]

the rockers were all “double nutted” and when trying to remove the top nut the studs came out of the block. I then removed all the passenger side ones and red locktited the stubs back in. Looking at the small threaded end in the block I decided to remove the heads and have them machined for studs and guide plates. Before I could start I found a set of rebuilt 1970 4 barrel heads on face book and grabbed them. I pick them up Monday and will have them machined and then swap the heads and sell the originals. See attached photos.

 

[Hemikiller]

If you're going to swap the heads, have new one piece valves installed. The OE Ford valves are a known failure point on these engines.

Scorpion makes an adjustable bolt-down rocker for 351C engines that might be something to look at once you get a quote on machining the pedestals.

https://scorpionracingproducts.com/product/3224-1-73-bbf-rocker-arms-adjustable/

 

[Sparky]

If you're going to swap the heads, have new one piece valves installed. The OE Ford valves are a known failure point on these engines.

Scorpion makes an adjustable bolt-down rocker for 351C engines that might be something to look at once you get a quote on machining the pedestals.

https://scorpionracingproducts.com/product/3224-1-73-bbf-rocker-arms-adjustable/

Hi - the quote for machining is $ 300 and the shop owner has done work for me for 30 plus years and runs 6 second dragsters. Add the cost of studs and guide plates and I am still under $ 600. This also allows me to change the cam as I have no idea what is currently in there. I may have to buy pushrods and will buy full roller rockers but will have a great engine when done. I can also sell the existing heads to recover some of my expenses. Which valves were the issue - intake or exhaust? I looked at some manly units online and may go that route. Thanks