Alfa Romeo Forums banner
1 - 7 of 7 Posts

·
Registered
Joined
·
148 Posts
Discussion Starter · #1 · (Edited)
Hello everyone.
I am in the process of having my cylinder head rebuilt as the head gasket was blown and I wanted to be sure the head was straight. I brought it to Norman Racing in Berkeley where they suggested to have it completely rebuilt as the components have never been changed in 45 years of service. While they are working on that I decided to dismantle every component around the engine and freshen them up, clean the mating areas and replace the gaskets with new ones. My intention is not to remove and rebuild the block, just freshen up the surrounding components. However, I have a couple of questions regarding the timing chain and the pistons.

My question is: is it normal to have so much slack in the timing chain and side movement play of the pitstons when at TDC? The pistons do not move at all when lower in the liner, only when they reach the top. They all have the same amount of play.
I made a video, which you can view below, illustrating these possible problems. You will also find photos of the pistons and liners for reference.

I checked the liners inside and they are smooth and I can't feel any grooves created by the piston rings. I believe the head gasket blew because the head was not torqued properly. In fact the head bolts were very easy to remove.
As I never removed the head of an engine before and do not have the knowledge or experience to recognize if this amount of timing chain slack and piston play is normal, I am kindly asking the alfabb comunity to chip in with its extensive knowledge.
Thank you all in advance.
Igor
















 

·
Super Moderator
Joined
·
12,090 Posts
is it normal to have so much slack in the timing chain
That does look like a lot of play in the lower timing chain. Either the chain has stretched due to wear in its pivots, or someone line-bored the crank main journals which shifted the crank upward. I'd get a new chain, and see what difference it makes. Before installing the new chain, compare the lengths of the old and new.

side movement play of the pitstons when at TDC? The pistons do not move at all when lower in the liner, only when they reach the top. They all have the same amount of play.
It's tough to see the piston side-side play in your video. You might bring it to Norman Racing and ask them.
 

·
Registered
Joined
·
13 Posts
Salve Samana,

the timing chain is too loose. It needs to be replaced.

Pistons and liners:

Do they still have the honing texture? If it is not visible anymore, it indicates that the liners are quite worn out. Do you can see/feel scratches? If so, the liners need to be replaced as well. Then would be the most economical way, installing new liners and pistons. They are available for a reasonable price.
How was the engine before disassembling? Oil consumption? Exhaust fumes blue smoke? Do have a compression-diagram? Milage?

In your place, I would take the engine out of the engine bay. Most of the work has been done already anyway. Only open the Motor / Gearbox bearing. Take off the gearstick. It is alot easier to work, and you get better results.


Saluti

Barista
 

·
Administrator
Joined
·
15,014 Posts
That does look like a lot of play in the lower timing chain. Either the chain has stretched due to wear in its pivots, or someone line-bored the crank main journals which shifted the crank upward. I'd get a new chain, and see what difference it makes. Before installing the new chain, compare the lengths of the old and new.
Agree.

If the crank main journals have been line-bored it is not the end of the world, just bore for a sleave and then machine for bearings where the chain idler shaft (not sure of the name) runs so that it also has been moved up the same amount. You would have to do this in the block and timing chain cover. This would mean that "slack" has been moved to the top/upper chain but that has adjustment.
Pete
 

·
Registered
Joined
·
964 Posts
Time to restore yet another old thread, eh. With 90K on the engine and given the fact the it has not been running for 15 plus years the rings, liners and wrist pins will need to be replaced. The pistons really done ware, eh? So why replace them other than they come in a kit?
 

·
Premium Member
71 Berlina 74 GTV 17 Giulia Q4
Joined
·
6,667 Posts
It's a 45 year old motor! You put a new head on top of old stuff and there's pretty much only one outcome. Do yourself and the car a favor, rebuild it right the first time you won't regret it. As far as the slack goes the intermediate gear is only supported on one side with the front cover off so it will have more slack. Even so....
 
1 - 7 of 7 Posts
Top