cams and timing after complete overhaul engine
03-19-2016, 12:33 PM
#16
Rennlist Member
wow, thanks MrMerlin for this detailed description! It becomes much clearer to me now. I have quite some experience in the electrical wiring of my 928 since I did a full rewiring of my 928 as it was a Christmas tree on the dashboard when I bought the car. So this has no secrets to me. On the other hand, the engine is quite delicate to restore. And you need to do everything by the book , if not, it might become quite expensive when engine fails afterwards.
btw : I searched 3 years to find a good replacement engine as the 4.7l 300hp Kjet engines are becoming rare, especially in Europe.
btw : I searched 3 years to find a good replacement engine as the 4.7l 300hp Kjet engines are becoming rare, especially in Europe.
03-19-2016, 03:03 PM
#17
Nordschleife Master
Factory states that all 16V cars are non interference.
I have verified that one 85 euro 16V was non interference, as well as an 84 euro (LH) was non interference as well (broken camshaft).
Erkka has stated on here that there was a cut off in the piston design that happened in mid 84 (VIN was posted) and that all before this are non interference.
It is always best to verify when the belt is off if it is non interference or not so that you know. But it is obviously better to treat it as if it is than it is not.
I've never heard of or seen bent valves on a 78-83 euro, but have on a 85/86 euro 16V.
But carbon build up, and prior mechanical repairs can easily turn a non interference engine into one.
I have verified that one 85 euro 16V was non interference, as well as an 84 euro (LH) was non interference as well (broken camshaft).
Erkka has stated on here that there was a cut off in the piston design that happened in mid 84 (VIN was posted) and that all before this are non interference.
It is always best to verify when the belt is off if it is non interference or not so that you know. But it is obviously better to treat it as if it is than it is not.
I've never heard of or seen bent valves on a 78-83 euro, but have on a 85/86 euro 16V.
But carbon build up, and prior mechanical repairs can easily turn a non interference engine into one.
03-19-2016, 03:21 PM
#18
Team Owner
I replaced 5 valves on my 85 Euro 16V 3 intake and 2 exhaust were bent
03-19-2016, 05:57 PM
#19
Former Vendor
Factory states that all 16V cars are non interference.
I have verified that one 85 euro 16V was non interference, as well as an 84 euro (LH) was non interference as well (broken camshaft).
Erkka has stated on here that there was a cut off in the piston design that happened in mid 84 (VIN was posted) and that all before this are non interference.
It is always best to verify when the belt is off if it is non interference or not so that you know. But it is obviously better to treat it as if it is than it is not.
I've never heard of or seen bent valves on a 78-83 euro, but have on a 85/86 euro 16V.
But carbon build up, and prior mechanical repairs can easily turn a non interference engine into one.
I have verified that one 85 euro 16V was non interference, as well as an 84 euro (LH) was non interference as well (broken camshaft).
Erkka has stated on here that there was a cut off in the piston design that happened in mid 84 (VIN was posted) and that all before this are non interference.
It is always best to verify when the belt is off if it is non interference or not so that you know. But it is obviously better to treat it as if it is than it is not.
I've never heard of or seen bent valves on a 78-83 euro, but have on a 85/86 euro 16V.
But carbon build up, and prior mechanical repairs can easily turn a non interference engine into one.
I should have thought more about my thinking and explained myself more.
Since I'm frequently building some hybrid version of these engines, I prefer to not take chances, by changing how I do things, and treat all of these engines as interference engines. This is just a safer procedure, for me.
Installing the cams (and carriers) is the same....regardless if the engine is at TDC or at 45 degrees BTDC. Installing the belt is the same....just need to count three teeth.
As always, individuals can do what they choose to do.
03-19-2016, 10:09 PM
#20
Nordschleife Master
I've seen bent valves on USA engines....certainly from carbon, but bent valves all the same.
I should have thought more about my thinking and explained myself more.
Since I'm frequently building some hybrid version of these engines, I prefer to not take chances, by changing how I do things, and treat all of these engines as interference engines. This is just a safer procedure, for me.
Installing the cams (and carriers) is the same....regardless if the engine is at TDC or at 45 degrees BTDC. Installing the belt is the same....just need to count three teeth.
As always, individuals can do what they choose to do.
I should have thought more about my thinking and explained myself more.
Since I'm frequently building some hybrid version of these engines, I prefer to not take chances, by changing how I do things, and treat all of these engines as interference engines. This is just a safer procedure, for me.
Installing the cams (and carriers) is the same....regardless if the engine is at TDC or at 45 degrees BTDC. Installing the belt is the same....just need to count three teeth.
As always, individuals can do what they choose to do.
I'm just stating my own observations. And past discussions on the matter here on RL.
On the 85 euro I had, I put each piston to TDC, and then rotated the appropriate camshaft, there was no interference, and the engine ran well after.
On the 84 euro, the drivers side cam snout snapped right off due to a prior belt repair job being done incorrectly (4 years prior to my meeting the gentleman who owns it). I did a leakdown test after pulling the cam, perfect leakdown. Runs great to this day.
I have also seen bent valves on non interference engines due to decking, carbon etc. And I always tell my customers to treat the car as if it is interference as there is no real extra cost to do so, yet if they bent, the cost is very high.
03-19-2016, 11:18 PM
#21
Former Vendor
I totally agree, and would treat every engine as if it were an interference engine personally.
I'm just stating my own observations. And past discussions on the matter here on RL.
On the 85 euro I had, I put each piston to TDC, and then rotated the appropriate camshaft, there was no interference, and the engine ran well after.
On the 84 euro, the drivers side cam snout snapped right off due to a prior belt repair job being done incorrectly (4 years prior to my meeting the gentleman who owns it). I did a leakdown test after pulling the cam, perfect leakdown. Runs great to this day.
I have also seen bent valves on non interference engines due to decking, carbon etc. And I always tell my customers to treat the car as if it is interference as there is no real extra cost to do so, yet if they bent, the cost is very high.
I'm just stating my own observations. And past discussions on the matter here on RL.
On the 85 euro I had, I put each piston to TDC, and then rotated the appropriate camshaft, there was no interference, and the engine ran well after.
On the 84 euro, the drivers side cam snout snapped right off due to a prior belt repair job being done incorrectly (4 years prior to my meeting the gentleman who owns it). I did a leakdown test after pulling the cam, perfect leakdown. Runs great to this day.
I have also seen bent valves on non interference engines due to decking, carbon etc. And I always tell my customers to treat the car as if it is interference as there is no real extra cost to do so, yet if they bent, the cost is very high.
And I think that the message we should send to the novice engine people....not details about what "technically" is true.
Which is why I made my initial post.
