Top-end Recommendations

[Wayne 962]

Originally posted by Damomma
I tell you I'm spooked, Wayne's recommendation on this board and in the rebuild book is to leave them together and do not disturb if they are Alusils. I don't know what they are yet because I can't find a 46mm crowsfoot in stock, so I can't tear the rest of the motor down.

That recommendation is straight from the mouth of Walt at Competition Engineering.

-Wayne

[HarryD]

Originally posted by HarryD

I think alot of the cost issues relate to the degree of machine work required. For the early engines, the magnesium cases tend to stress relieve over time. If you spilt the case, you need to machine the halves to get the faces to align properly on reassembly. Am I mistaken in thinking that the later, aluminium cases do not have this issue?

Originally posted by Wayne at Pelican Parts
You can't compare machining costs on a magnesium case to machining costs on an aluminum case. Typically the aluminum cases require nothing but a cleaning.

-Wayne

Am I to understand that if you have a Magnesium case, the cost of doing the bottom end does entail some hefty costs due to the addtional machine wrok required?

Assuming this is true, when do you decide to go into the bottom end of a magnesium case? I can see the need due to spun bearings, or other obvious damage but how about when there is no damage indicated? As I stated before, I "took a chance" with my 116,000 mile engine and did the only the valves. There is not indication that I needed to go further. How would I tell if more work is needed? Also, if I do need to go into the engine again, for the next 50,000 miles or so, can I "get by" with gaskets, rings, and machine work on the bottom end and leave my heads alone?

[Wayne 962]

Let me add some more. My thoughts on the bottom end are based on the fact that you can tear it down quite easily when it's out of the car. An aluminum case *should* not require any machine work, although your Euro Carrera may not have the updated oil pump in it (I can't recall if the switchover was mid-year 1976 or if any early 1976 cars squeeked through with the old pump).

You can tear down the bottom end and measure/inspect the bearings. I know people who have reused bearings if they measured 100% in spec. While I wouldn't do it on my own engine rebuild, it's difficult to argue against keeping parts that are still in spec. It gives you a good chance to measure and check your rod bearings, and your intermediate shaft bearings, which seem to wear on these engines (they are only $30 or so to replace).

So, an alternative option would be to tear down the bottom end, inspect, and reuse any bearings (after measuring them with the case bolted back together, minus the crank) if they all meet the specs. This is not what I recommend, but it's not a horrible path either. At least you know what's good and what's bad in the engine, and might be better than simply ignoring it.

Then again, it might be perfectly fine in there, and the bottom end may last another 100K. If it were me, I would take a look, but I typically want everything to be 100% perfect.

-Wayne

[HarryD]

Originally posted by Superman
Nope, it sure will not double your cost. In fact, part of what Wayne and others are reporting is that the engine's bottom end is clearly the simplest part of the engine. Not much there to replace in fact, except the hardest working parts in your engine. The bearing shells. Measure (machine if necessary) the rods, and measure/inspect the crank, and you're into it for another $500, maybe.

Originally posted by Wayne at Pelican Parts
Yes, all magnesium cases have the potential to need extensive machine work. The earlier cases less so, because they were exposed to less stress. Typical cost to have everything done is about $1500 at Competition Engineering (although they are so backed up right now). Check out the machine shop costs table in the Engine Rebuild Book.

I think these two posts clarify some of the back and forth we see on the issues relating to doing the bottom end "while you are in there".

From this I would surmise the cost difference in doing a full rebuild is $500 for a 3.0/3.2L aluminum block engine and $2,000 for a 2.xL magnesium case engine. This is a hefty jump in cost and for us early eninge owners, we may choose to defer the extra cost.

Funny how a few blind guys can describe an elephant so differently.