So, I thought I could get away with a casual rebuild of my spare DFZ. Turned out I would need to deck the block and liners as the chamfered sealing face was corroded from the flat right the way down. I kept the pistons and crank, which has just been checked over and polished keeping the std/std journals.
In my due haste trying to get a smoke-free engine to get down to 2 regos with upcoming baby no1, the current DFZ in the car was ripped out. I suspected it would have had more frequent coolant changes even though it has 100k more on it. Sure enough it isn't too bad but I have work to do:
The machinist is too busy with other people's messy projects so he told me I should be getting some Devcon Aly epoxy. Theres a 500g pack of 10610 Aluminium putty for ~$150, or 184g pack of 19770 Fasmetal 10 for ~$50. Both are almost identical in properties on the spec sheet, apart from chemical resistance. I'm still unsure as to why there is a wet and dry max operating temperature of 49deg and 120deg respectively.
If anyone has repaired one of these alloy blocks with epoxy please chime in. The machinist has said he has seen far worse on Alfa engines that have been repaired and are still operating today.
While I waited for the engine to get blasted I went about cleaning the engine bay.
Brake fluid had managed to lift the paint under the clips for the hardlines but didn't start rusting yet. Interestingly I found the start of rust on the seam above the exhaust. The same seam that was completely rotten from wheel to wheel on my old car.
A bit of rust converter a rattle can and clear engine enamel on the tunnel, the bay is the cleanest it's ever been.
I still need to think about the head. I've got an Si head, a virgin DFZ head and another DFZ head (from this engine) that's 1mm shallower than the virgin head. I don't think I have the appetite to deal with 10.5:1 CR on a street engine, but if I am getting a valve cut job, can the machinist not mill the chamber to increase CR and thus retain the slightly bigger valves of the Si head?
Since the skimmed head has about 5cc less than the standard DFZ head that would bring its volume to an estimated 44cc with a 1mm gasket so I've effectively been running 9.1:1 - might explain why the dizzy advance was blocked off when I got the car but I've never detected pinging on 95 since I reattached it.
More to come, hopefully..
In my due haste trying to get a smoke-free engine to get down to 2 regos with upcoming baby no1, the current DFZ in the car was ripped out. I suspected it would have had more frequent coolant changes even though it has 100k more on it. Sure enough it isn't too bad but I have work to do:
The machinist is too busy with other people's messy projects so he told me I should be getting some Devcon Aly epoxy. Theres a 500g pack of 10610 Aluminium putty for ~$150, or 184g pack of 19770 Fasmetal 10 for ~$50. Both are almost identical in properties on the spec sheet, apart from chemical resistance. I'm still unsure as to why there is a wet and dry max operating temperature of 49deg and 120deg respectively.
If anyone has repaired one of these alloy blocks with epoxy please chime in. The machinist has said he has seen far worse on Alfa engines that have been repaired and are still operating today.
While I waited for the engine to get blasted I went about cleaning the engine bay.
Brake fluid had managed to lift the paint under the clips for the hardlines but didn't start rusting yet. Interestingly I found the start of rust on the seam above the exhaust. The same seam that was completely rotten from wheel to wheel on my old car.
A bit of rust converter a rattle can and clear engine enamel on the tunnel, the bay is the cleanest it's ever been.
I still need to think about the head. I've got an Si head, a virgin DFZ head and another DFZ head (from this engine) that's 1mm shallower than the virgin head. I don't think I have the appetite to deal with 10.5:1 CR on a street engine, but if I am getting a valve cut job, can the machinist not mill the chamber to increase CR and thus retain the slightly bigger valves of the Si head?
Since the skimmed head has about 5cc less than the standard DFZ head that would bring its volume to an estimated 44cc with a 1mm gasket so I've effectively been running 9.1:1 - might explain why the dizzy advance was blocked off when I got the car but I've never detected pinging on 95 since I reattached it.
More to come, hopefully..