NEW UPDATE:12/08/16 - pulling heads MORE QUESTIONS!

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bobmarlojill

Well-known member
Joined
Aug 16, 2013
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Location
Illinois
My Car
1973 Mustang Convertible, 351C 2v, Full restoration
I am going to pull the heads of my 351C in my 73 and was wondering if there is a way to know what year the engine is by the casting numbers on the heads. I don't think its original to the car. Im taking them in to be rebuilt and wondering if he is going to ask me what year.

Also want to make sure I get the correct head gaskets.

Thanks

UPDATE 12/07/16


Started removing parts to pull heads and now I have a couple casting numbers. See pictures. First picture of head, second of intake. So to me this shows its a 69 correct? Would this be out of a 69? Or was it made in 69 and probably put into a 70?


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Bob,

The heads have a date code on them...see pic below. On my head it shows 3E24 which equates to May 24,1973.

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Both of your date codes are October of 1969, which would make sense for a 1970 MY engine. If I had to guess, your motor is a '70 model....


Ha, took me too long to type!

 
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Bob as other have said it is an early 70 engine

Just incase you didn't know your early rockers do not have the oil splash shields. You need rocker covers with the shields on them, or you can add the ones on the rockers during the rebuild.

Don

 
Bob as other have said it is an early 70 engine

Just incase you didn't know your early rockers do not have the oil splash shields. You need rocker covers with the shields on them, or you can add the ones on the rockers during the rebuild.

Don

Don, Is there much difference between the 70 i have compared to the 73 engine that would have came in my car as far as HP?

Im not familiar with the splash shields....are they just for keeping the rockers lubricated better? Do I just add them to what I have? Where are they available and is the a better brand I should look for?

Thanks for the help!

Bob J



Bob the date codes on heads and intake indicate October 1969 which would have been used in a 1970 vehicle.
thanks Jeff....any idea if 1970 would be ready to burn unleaded fuel? Im not sure when they started switch from leaded. I am wondering if my exhaust valve leakage is because it doesn't have hardened seats.... I bought this from someone that drove about 5000 miles on unleaded fuel and they don't know if anyone put hardened seats when the engine was built.

 
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the reason I was taking the heads of is because I had low compression in a couple cylinders.... the worst being the 3rd one from the front. After a leakdown test I came up with the conclusion that the exhaust valve was the problem. This engine was supposedly built shortly before I bought it but it did sit for about 4 years before I ran it and it smoked mainly out of passenger side. After pulling the head I don't see much with the initial look at the head:chin:...

The engine does seem really clean. The honing in the cylinder doesn't look like it has many miles.

Does anything jump out at you all when looking at these new pictures?

Can anyone tell if this has hardened seats by the picture?

I have never rebuilt a Cleveland.....what is the deal with the intake gasket like this? looks like a heat shield?

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the reason I was taking the heads of is because I had low compression in a couple cylinders.... the worst being the 3rd one from the front. After a leakdown test I came up with the conclusion that the exhaust valve was the problem. This engine was supposedly built shortly before I bought it but it did sit for about 4 years before I ran it and it smoked mainly out of passenger side. After pulling the head I don't see much with the initial look at the head:chin:...

The engine does seem really clean. The honing in the cylinder doesn't look like it has many miles.

Does anything jump out at you all when looking at these new pictures?

Can anyone tell if this has hardened seats by the picture?

I have never rebuilt a Cleveland.....what is the deal with the intake gasket like this? looks like a heat shield?
That gasket is the "Valley Pan" I have heard several different explanations on its purpose. These two seem to be the most plausible.

1. To keep the exhaust crossover in the intake manifold from heating up the oil. (seems to be the best explanation to me)

2. To keep the hot oil from heating up the bottom of the intake manifold.

Also the 1970 engine should have higher compression and more HP than a 73.

 
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Bob, it's hard for me to say for sure whether or not you have hard exhaust seats, but from what I see, I'd say no. Borrow a valve spring compressor from one of the auto parts stores (autozone and o'reilly typically loan this sort of tool) and pull the valves on the suspect cylinder.

One thing I notice is the plug in that cylinder looks to be lean or nearly a brand new plug. The exhaust valve appears to be sunk into the seat, but again, hard to tell from a picture. The top of the valve should be slightly above the portion of the seat just beyond the valve head OD.

5000 miles on unleaded isn't enough to cause a problem with exhaust seats. The smoking could be a sign of an intake runner sucking in oil and leaning out a cylinder. The valley pan (intake gasket) has a raised rib just inboard of each port opening. This gets crushed when the intake is torqued....take a look and see if you can find a portion of that rib that isn't flattened out.

There's a tiny mark on the exhaust valve relieve in the pic with single cylinder/piston shown...check the push rods to see if any are bent....a telltale that a valve contacted a piston for whatever reason. Was there any clattering from the engine?

Lots of knowledge on this site...I'm sure you'll get some good input from others.

 
I believe you had a blown head gasket-though the pictures make it hard to see.

Also the turkey pan can make sealing the intake manifold a little tricky. If the intake gaskets are bad, they will allow the intake to suck oil into the cylinders.

Hardened valve seats are something not everyone agrees on. While they do have advantages, they also have the drawbacks of possibly cutting into the water jacket when installing them and if not installed properly they can come loose and cause all kinds of damage. While not having them will likely mean a valve job after 50,000 miles of use-that's a lot of mileage for a hobby car.

My advice would be a valve job with new 1 piece stainless valves and have it done by someone that is willing to do it right, then reassemble with fresh gaskets without using the turkey pan.

 
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Bob, it's hard for me to say for sure whether or not you have hard exhaust seats, but from what I see, I'd say no. Borrow a valve spring compressor from one of the auto parts stores (autozone and o'reilly typically loan this sort of tool) and pull the valves on the suspect cylinder.

One thing I notice is the plug in that cylinder looks to be lean or nearly a brand new plug. The exhaust valve appears to be sunk into the seat, but again, hard to tell from a picture. The top of the valve should be slightly above the portion of the seat just beyond the valve head OD.

5000 miles on unleaded isn't enough to cause a problem with exhaust seats. The smoking could be a sign of an intake runner sucking in oil and leaning out a cylinder. The valley pan (intake gasket) has a raised rib just inboard of each port opening. This gets crushed when the intake is torqued....take a look and see if you can find a portion of that rib that isn't flattened out.

There's a tiny mark on the exhaust valve relieve in the pic with single cylinder/piston shown...check the push rods to see if any are bent....a telltale that a valve contacted a piston for whatever reason. Was there any clattering from the engine?

Lots of knowledge on this site...I'm sure you'll get some good input from others.
The engine runs very smooth and quite....that's why im having a problem with tearing this motor down. Just smokes and low on compression. Thanks for the ideas



I believe you had a blown head gasket-though the pictures make it hard to see.

Also the turkey pan can make sealing the intake manifold a little tricky. If the intake gaskets are bad, they will allow the intake to suck oil into the cylinders.

Hardened valve seats are something not everyone agrees on. While they do have advantages, they also have the drawbacks of possibly cutting into the water jacket when installing them and if not installed properly they can come loose and cause all kinds of damage. While not having them will likely mean a valve job after 50,000 miles of use-that's a lot of mileage for a hobby car.

My advice would be a valve job with new 1 piece stainless valves and have it done by someone that is willing to do it right, then reassemble with fresh gaskets without using the turkey pan.
thanks for the help


what do you guys think about the carbon missing around the edges of the piston top? I have heard people say in the past that that is a sign of ring problems. Do you think these look normal?

 
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I think the carbon is cleaned off by the oil, but if it is a result of a leaking gasket drawing oil in, then the rings aren't necessarily bad.

I would rebuild the heads and reinstall everything with good gaskets. Compression numbers with poorly seated valves or a blown head gasket won't be up to snuff-so once you fix that I think you have a good chance of having a nice running engine-if You still have issues after that you've wasted some gaskets and the other work would have been just as necessary.

 
In regard to Jeff's thought about a head gasket: What color is the smoke coming from passenger side and does the "smoke" linger or does it rapidly dissipate? If it's blue and lingers, then it's oil of some sort (could be trans fluid coming from a blown vacuum modulator, for example). If it dissipates, it's steam and supports the leaking head gasket. I don't see any piston tops that are clean. Generally, a coolant leak into a cylinder will clean up the affected cylinder(s), but not always. Did you scrape the carbon off the center of the picture which shows only 1 piston top and the .030 stamp is visible?

Do all of the plugs look like the one shown in the picture and are the plugs new? As I said before, that plug looks lean or very new. A lean cylinder is certainly a cause for a burned exhaust valve and could be the root cause of your issue.

As far as the carbon, this looks to me like an engine with low miles.

 
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In regard to Jeff's thought about a head gasket: What color is the smoke coming from passenger side and does the "smoke" linger or does it rapidly dissipate? If it's blue and lingers, then it's oil of some sort (could be trans fluid coming from a blown vacuum modulator, for example). If it dissipates, it's steam and supports the leaking head gasket. I don't see any piston tops that are clean. Generally, a coolant leak into a cylinder will clean up the affected cylinder(s), but not always. Did you scrape the carbon off the center of the picture which shows only 1 piston top and the .030 stamp is visible?

Do all of the plugs look like the one shown in the picture and are the plugs new? As I said before, that plug looks lean or very new. A lean cylinder is certainly a cause for a burned exhaust valve and could be the root cause of your issue.

As far as the carbon, this looks to me like an engine with low miles.
The exhaust smoke is blue and lingers....oil for sure. I did scrape the one piston to see what it had been bored out to. The plugs are all new wit h just a few miles. I really appreciate everyone's feed back!

 
I'm by no means an expert, so I don't know what value my thoughts have, but a couple of things:

1. The picture of the bores makes it look like a quickie hone job over a bore with some wear. I think I see cross hatch over ring wear ( taper) at the top of the bore, and to me that sounds like a re-ring job, not a true rebuild. It could be that since it's already at 0.030" over it was decided to not do another overbore.

2. It does look like the valve seats have some wear and the valves are sinking. An easy way to tell us to look at the tip height of the valve or installed height, but this is harder to eyeball on a Cleveland with its compound valve angles. How do the valves look in the chambers from cylinder to cylinder?

-Matt

 
What Matt is saying about the hone marks looks true. I would measure the bore and see what the recommended clearance is for the type pistons in the engine. Might be honed way too big and rings would be very slow to seat if they are.

I never did see all the casting numbers on the heads are the DIAE with the GA which would be the 64 cc closed chamber?

Don't you just hate when you don't know what they did. A guy once told me he rebuilt his engine and after pumping him for info all he did was take it apart and put back to together with new gaskets. No overbore no crank grind nothing. That was his version of a rebuild.

David

 
A quick and dirty leak check would tell you if the seats are leaking....level off the head and fill each combustion chamber with solvent, diesel, kerosene...something with low viscosity that won't cause corrosion and inspect inside each port for fluid on the other side.

Good advice from David to mic the bores. I'm not seeing anything unusual about the cross hatch...cross hatch wears most at the top of the stroke where cylinder pressure forces the rings against the cylinder walls, but like Matt said, I'm no expert. It did make me think of something else....notice how the hatch has worn the most at the top of the stroke and you can see where the top and 2nd ring top out....if you see a cylinder that doesn't have that wear pattern, it's an indication a ring was installed upside down...and that would definitely cause lower compression and blue smoke....I know this from personal experience :) Was my first 4-stroke rebuild when I was 15.

 
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