420A engine assembly

[studabaker]

I am documenting my 420a rebuild in the sacramento area forum. I have a question that I would like to expose to everyone. I have installed up to the cams and as I was installing the clutch i was rotating the crank and pistons and it would rotate only to the same spot almost and seem to catch on something. One piston was not oriented the same as the other three but they seem perfectly symetrical. The writing was upside down. All the valves are closed. I need to be sure this is ok before putting the engine back in the car...
Thank you

 

[bryanwheat]

So you put one of the pistons in backwards?

 

[studabaker]

thank you, yes.
I did not want to take the head off again.
The orientation of the dot is i guess an indicator. It seems that they require to be in a consistent direction because without the one that had the dot on the clutch side and the rest had the dot on the oil pump side then the crank will rotate continuously in either direction. I knew the driections said to follow the arrow however mine have a dot. My pistons have the lightening bolt which is sealed power.

 

[bryanwheat]

Take it back apart and fix that.

 

[studabaker]

The engine rotates in either direction easily now more than one revolution with all indicator dots to the oil pump side. This allows me to put just the block in without the head which will be easier to manouver with 30 less lbs and smaller. It will be no problem torquing down head inside with motor mount on and bolted to transmission. The clutch is on obviously and I am going to press on the crank pulley and harmonic balancer. I was going to try an under drive pulley and my harmonic balancer has a chip out of the edge but I have to wait for cash.

 

[962ndgen]

thank you, yes.
I did not want to take the head off again.
The orientation of the dot is i guess an indicator. It seems that they require to be in a consistent direction because without the one that had the dot on the clutch side and the rest had the dot on the oil pump side then the crank will rotate continuously in either direction. I knew the driections said to follow the arrow however mine have a dot. My pistons have the lightening bolt which is sealed power.

on aftermarket pistons any "dots/marks" on the piston skirt is a indicator of which way the piston should face towards either the front or rear of the engine you will HAVE to take the head back off OR drop the oil pan turn over the engine drop the piston put it back on how it should sit and put her back in.

 

[bryanwheat]

on aftermarket pistons any "dots/marks" on the piston skirt is a indicator of which way the piston should face towards either the front or rear of the engine you will HAVE to take the head back off OR drop the oil pan turn over the engine drop the piston put it back on how it should sit and put her back in.

Watch it with the bad information, pistons don't come out thru the bottom. that green dot will turn red real quick with answers like that.

 

[studabaker]

I guarantee the pistons wont come out the oil pan. He did mean that the engine needed to be turned which must have meant that when the engine is on a stand you would have to unbolt the connecting rod and push the piston out gently. If you tap on the connecting rod do your best to make sure it is not at an angle as it will only push the piston against the side of the cylinder. Also fyi it will not rotate in place. I tried it because I am borrowing the piston ring compressor from parts stores and I wanted to try and rotate the piston before I removed it which does not work...

Mine has a mark that is a divot out of one side of the surface. There is a lightning bolt on the side but I think its the same on both sides. I don't remember. I have put about 20,000 miles on them the image is slightly worn on one. This dot is actually carved out of the top surface.

This actually helped me because I just put the block in the car and attached it to the transmission. I think I would have had more trouble with the head on. Also none of the brackets could be on during engine to transmission attachment. exhaust mount maybe.

I had two connecting rods replaced and the crank ground and over sized bearings. My crank bolt went missing which I am working on finding at a hardware store eventually. It will be close enough anyway. I think mine may have been slightly bent anyway. I will press on the belt pulley and harmonic balancer using a 150 mm bolt of the same size which is m12 1.75 120 mm (stock bolt).

Anther fyi I am using a chain hoist to put the block in and it needs an angle lifting up on the passenger engine mount to fit the clutch in the transmission housing. I attached the engine mount and then put a jack under the transmission mount and lifted it slightly.

My thread is called "diagnostic help" in Sacramento region.

Thank you for being there I credit this site fr my ability to accomplish this task.

 

[studabaker]

I have learned to set the timing on a stand and install the engine without the harmonic balancer and putting the clutch inside the transmission housing before lowering the engine. The clutch can be bolted on with the engine mounted to the trans.. The engine has to be lowered to install the harmonic balancer but it fits much better and the timing was not set perfectly with the harmonic balancer on because I could not see the mark on the gear to line it up. I have also had a significant problem with oil leaking out the rear main seal which is seated correctly in this picture. I had been installing it too far and resulted in a pretty bad leak. The seal is approximately the size of the end of the crank so if there is more than a mm exposed it may be that much over on the block side.

 

[Blackfuse]

Do whatever is necesarry to turn that piston around. Make sure they are oriented correctly.


Nore that the pins on the pistons are not on the center of the piston this defines the direction of the rotation after the combustion occurs. One piston backwards is not good.

Also make sure you rings are gapped correctly and ring gaps are opposite of each other.