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To recap, I have a 1983 Esprit Turbo which I owned from 2007-2013, I sold it to another guy and he failed to change the timing belt as I advised. His mechanic dismantled it and the project was abandoned. This left it with a scored cylinder, a slightly damaged head, two bad pistons, missing valves/springs and many other parts. I just bought the basket case back with the intent of fixing it.

I also bought another 910 engine (1984) from another source. It had compression in all cylinders, and seemed ok. My plan was to "pop" that engine in and run it while slowly rebuilding my original engine. But then I became convinced that I needed to remove its crankshaft and bore it out to solve the needle bearing issue. So NOW my tear down has revealed that I have a crack in one of those pistons between the rings. Inexplicably, no damage at all to the cylinder wall, on which I can still see crosshatching. As I turned to my original engine for a potential used piston to replace it, I realized that my original engine has HC pistons and aluminum HC liners which must have been installed by a previous owner prior to 2007. So now that I'm considering new pistons/liners in the 1984 temporary motor, I'm really questioning why I'm not simply rebuilding the 1983.

Problem: need a motor!
Resources: I have an 83 block and an 84 block. The 83 block has aluminum HC liners (one requiring replacement) and 2 good looking Mahle HC pistons. The 84 block has the iron liners (all seemingly good) and 3 remaining AE/Hepolite pistons. The 83 block is the original engine to my car.

Anyone have a used AE/Hepolite piston for sale?

Advice?

-Jason
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Discussion Starter #2
I should mention, I emailed JAE and I do have the prices on replacing all the pistons and on replacing the liners. While I may do that later on the 83 engine, I thought I would have an easier and cheaper project in reviving the 84.
 

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Since the '84 motor is bad and you can't "just pop it in" and you were going to eventually rebuild the '83 motor and put that one into the car, my advice now would be to just do the '83 motor and keep your car original. You should not have to replace all of the pistons and liners, just the bad ones. You "may" be able to use the '84 head on the '83 motor if you want to keep the cost down or at least many of the parts. Since a lot of the work will be done by a machine shop, the amount you would do in either case is about the same. You will spend more money fixing the '83 but you won't have to spend anything rebuilding the '84 motor. You also save all of the work later swapping the '84 out for the '83 motor. Later you should be able to sell off what is left of the '84 motor to recoup some of your expenses. Fixing up the '84 motor will not get you enough back to cover what you will spend on it especially if you don't use it and run it so it should be sold as parts so the next person can do it and know what goes into it and that it is good. BTW that piston was overboosted so there may be other parts that are in need of replacement. Like ALL of the pistons. Just my $0.02
David Teitelbaum
 

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David, thanks for that. What leads you to say overboost? (Could easily be, as this replacement motor was missing its turbo.) To my stupid eye, it looked more like a casting flaw on the bottom inner edge of the section between the rings. Before I started fiddling with it and reinserting it in incredulity to make it magically reattach, there was residue built up along one half of the crack as if it had operated that way for a while and my removal of the piston is what finally did it in. It fits super snug between the rings and they basically pulled the shard out as it was removed.

Here are pics of the head and block as they were separated.

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I am in the process of building up an '87 long block for use in my '83 specifically to get the aluminum liners. I am on borrowed time on the '83 engine as my wastegate has a leaky diaphragm and I overboost a lot. It's fun by the way.... I expect the #4 piston to crown and eventually fail, but the danged engine runs like a train, so I haven't been too motivated to swap it out. I would recommend going with the block that has already been modified for the aluminum liners and go with forged pistons. You can safely run more boost that way, even on carbs. You will need to tune your carbs to run a bit richer if you do go with more boost.

If you decide you are going to part out the '84 engine, I would be interested in the crank, con rods, oil feed pipe & associated bits and the cam carriers/tappets.
 

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Cracked piston lands are a hallmark sign of combustion chamber overpressure.Because of the sharp change in shape, stress gets concentrated there. The fix is to go to forged pistons or just not let the boost levels get that high.Since one of the pistons did fail because of being overboosted you can figure that the other pistons also experienced severe stress too.The good news is the motor was pulled out of service before it experienced catastrophic failure. Whoever was running it must have noticed the blue smoke and excessive oil consumption though and knew what happened. This is one of the possibilities when you buy a used motor that you didn't see run. At the very least you want to pull the spark plugs to see what is going on and do a compression test if you can. Otherwise you have to figure the motor is just for parts or a complete rebuild. No way to know how many miles on it.
David Teitelbaum
 

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Ring land failure can be from engine knock, so look out for lean mixtures & overly advanced timing as well as too much boost.

I seem to recall the pistons have fit classes, so you may need to check which one you need for your liner.
 

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Hi,

By chance, with all this talk about 910 engines, does anyone have a crankshaft timing gear(half moon tooth variation) for a 910 engine for sale?

Thanks,
Rich
 

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Discussion Starter #9
'87 long block for use in my '83 specifically to get the aluminum liners.
The more I've thought about it the more I like the idea of abandoning the 84 iron lined in favor of recovering the original 83 which has the aluminum liners. 3 liners look good and I need to accurately measure them. One has a score inside almost a mm deep , 2 mm wide, and... Say 6-9cm long. So. Gotta figure that.
 

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Engine knock, detonation, would burn the pistons and valves. The combustion chambers would look much whiter.On a motor with a turbo this looks like overpressure.
David Teitelbaum
 
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