Timing Chain Cover crankshaft opening is the wrong size

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fulltank

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I bought a new timing chain cover and I thought I had the right one as the timing marks lined up on the drivers side but as it turns out the new opening for the crank shaft is larger than the original, will it still work ? or am I better off getting another one that is the same size opening as the original. I never realized there were so many variations . This is a 68 LA 318 engine, in my Dart. When it was rebuilt they used a 73 318 block but kept the 1968 components, the water pump is the original 68 style. The timing cover rotted out from coolant corrosion so I have to change it all out . I read some of the install process on the forum but didn't come across this scenario tks.
 
fulltank said:
I bought a new timing chain cover and I thought I had the right one as the timing marks lined up on the drivers side but as it turns out the new opening for the crank shaft is larger than the original, will it still work ? or am I better off getting another one that is the same size opening as the original. I never realized there were so many variations . This is a 68 LA 318 engine, in my Dart. When it was rebuilt they used a 73 318 block but kept the 1968 components, the water pump is the original 68 style. The timing cover rotted out from coolant corrosion so I have to change it all out . I read some of the install process on the forum but didn't come across this scenario tks.
Click to expand...
Post a photo showing the part number on the cover. Arn't there two different seals?
 
There are at least 3 timing covers.

67(maybe 64) to 68 no timing marks on the cover. Seal installs from the inside (Uses a bolt on timing mark on the pass side)

Screenshot_20240504-161247.png

Screenshot_20240504-161436.png
Screenshot_20240504-161458.png



69 one year only. Timing marker is part cover BUT on the pass side (red)

Seal installs from the inside (green) smaller external opening
Screenshot_20240504-154821.png



70 to 73? timing marker is part of the cover and on the driver's side. Seal installs from the inside.

Screenshot_20240504-155011.png


73? And up timing marker is part of the cover and on the driver's side. Seal installs from the outside (this one has a 78 date mark on it)

Screenshot_20240504-160141.png




Somewhere the the seal went from installed from the inside to the outside.

Inside seal is smaller then outside seal.

Rock Auto suggests 12/72

Screenshot_20240504-153904.png



If you have a 68 setup and 68 damper it should have a bolt on timing mark on the passenger side.

You mentioned the block is a 73 and I assume they used the 73 damper. If so you have to use the 70 up cover, or change the damper to a 67-69 style and get a 67-68 cover and marker.


BTW...

The 69 and older damper timing mark does not line up with the 70 up marks on the cover.
 
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One has the seal install from the front and one has the seal install from the backside. That new one is like the later model version (76-and later I believe?) which installs the seal from the front.
 
This is the backside of the harmonic balancer, is the cap ring attached to it going to interfere with
the crankshaft seal for the new timing chain cover, just trying to cover all the steps.

Harmonic Balencer.jpg
 
fulltank said:
This is the backside of the harmonic balancer, is the cap ring attached to it going to interfere with
the crankshaft seal for the new timing chain cover, just trying to cover all the steps.

View attachment 1716245476
Click to expand...
Looks like it needs a repair sleeve or get a new balancer. See the wear marks in the balancer snout?
 
RustyRatRod said:
I'm blown away that you cannot see that the first timing cover HAS a seal in it. That's the hole in the SEAL you're measuring. Damn.
Click to expand...
I saw the seal but even if I take it out the opening is still smaller than the new timing cover
 
The seals for a 68, 69, 70... are all the same. They only changed HOW they install. Later ones go in from the front. Just get one and pound it in. Don't overthink it.
 
fulltank said:
I bought a new timing chain cover and I thought I had the right one as the timing marks lined up on the drivers side but as it turns out the new opening for the crank shaft is larger than the original, will it still work ? or am I better off getting another one that is the same size opening as the original. I never realized there were so many variations . This is a 68 LA 318 engine, in my Dart. When it was rebuilt they used a 73 318 block but kept the 1968 components, the water pump is the original 68 style. The timing cover rotted out from coolant corrosion so I have to change it all out . I read some of the install process on the forum but didn't come across this scenario tks.
Click to expand...
Okay, first off if you have timing marks on the driver's side, it's not a '68 318 timing cover. A '68 front cover will use a cast iron water pump with a driver's side inlet. With driver's side timing marks, it should be using the later aluminum water pump with a passenger side inlet. using the wrong pump on the wrong timing cover will hide your timing marks behind the loser radiator hose and pump inlet, making them very near unusable. Not to mention the fact that if the timing covers were swapped, your balancer needs to have it's timing mark relocated, since it will be nearly 90* off with the timing marks switching sides.
 
Thanks, so I just need to order a seal from a 68-70 and it will fit the new one great !
the water pump is the original 68 style cast with the main inlet on the drivers side (Pre 1970)
Are 318 harmonic balancers with the timing alignment on the left interchangeable or are there specific years
that will only work.
 
Professor Fate said:
Okay, first off if you have timing marks on the driver's side, it's not a '68 318 timing cover. A '68 front cover will use a cast iron water pump with a driver's side inlet. With driver's side timing marks, it should be using the later aluminum water pump with a passenger side inlet. using the wrong pump on the wrong timing cover will hide your timing marks behind the loser radiator hose and pump inlet, making them very near unusable. Not to mention the fact that if the timing covers were swapped, your balancer needs to have it's timing mark relocated, since it will be nearly 90* off with the timing marks switching sides.
Click to expand...
Ive used a timing light to set my distributor until now I never realized the timing cover was changed from passenger side to drivers side timing. (it was done before I bought it and Ive owned it for almost 30 years) If I changed the water pump to a passenger side outlet the radiator would not connect, does it mean Id have to change the rad as well ?
 
fulltank said:
If I changed the water pump to a passenger side outlet the radiator would not connect, does it mean Id have to change the rad as well
Click to expand...
The timing cover is water pump independent.

If your setup is working leave it.

I would check that TDC is TDC on the damper.
 
fulltank said:
Ive used a timing light to set my distributor until now I never realized the timing cover was changed from passenger side to drivers side timing. (it was done before I bought it and Ive owned it for almost 30 years) If I changed the water pump to a passenger side outlet the radiator would not connect, does it mean Id have to change the rad as well ?
Click to expand...
If you've got the iron water pump on the '70 and up timing cover, I'm shocked that you can even see the timing marks to use the timing light- kudos! The marks should be accurate (reasonably) as long as you've got the '73 damper on it with the '70 and up timing cover. No need to change anything as long as you can see the timing marks.
 
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