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Old 02-12-2007, 05:44 AM
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'66 911 #304065 Irischgruen
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Ex-'88 Carrera (Sold 3/29/02)
Ex-'91 Carrera 2 Cabriolet (Sold 8/20/04)
Old 02-12-2007, 05:47 AM
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A few short comments at the moment. First, a HUGE thank-you to Dr. John Colasante, who was of invaluable assistance with the teardown. Note to readers: It is IMPOSSIBLE for one person to break the cam nuts free.

1) With the exception of cylinder #4, EVERY top compression ring was broken, some in multiple places. When the engine was rebuilt in 1982, the previous owner did not replace the pistons. Just like it says in all the books, if the top ring gap is too wide, new rings will break. Which is exactly what happened.

It's also comforting to actually FIND the problem-- remember from my other thread that two leakdown tests performed at different times indicated this engine was leaking down 30%, with the noise coming from the crankcase breather. Open it up and. . . broken rings on FIVE cylinders.

2) Look at the blue heat distortion on the #8 main bearing. Now obviously the bearing cannot have "spun" because it's held in place with a dowel pin. It is possible, however that it was installed incorrectly, with the locator pin in the oiling hole, or that the bearing is otherwise clogged. I don't have a photo of the snout of the crank just yet, but there's definitely scoring on the end, only the micrometer will tell.

3) Main bearings and journals looked good! No scoring or evident wear, the only spot where copper was showing is at the chamfer around the oil holes, probably put there on installation.

4) Just like the idler sprocket pictured above, the intermediate shaft sprockets are worn to a point and will be replaced.

5) The pistons will be replaced with a modern slipper skirt design, invisible to all. You can see all kinds of crazy things on the factory pistons, most notably, scuffing of the skirt and carbon buildup on around the pin bosses.

6) Black silicone was used as a sealant for the cam box to head junction, and it appears as though it was also used to seal the case. Very, very, very incorrect. In other photos you can see black-squeeze-out dangling from the case seams.

7) Look at the cute little oil pump! It's going on a shelf, will be replaced with an SC pump along with the oil bypass mod and squirters.

8) Most of the headstuds in the port case half came out, only two remain that wouldn't come out with the stud-puller or vice grips (!) Given the age of the studs and the cost of new steel studs it did not make sense to take a chance, 41 years of heat cycles is plenty. I would like to remove ALL the case studs to inspect and black-oxide passivate them but that's a much more complicated job down the line.

9) Look at the little rocker shafts! Note the short one, it has a 5mm pinch bolt and an 18x49mm shaft. In 1967 the factory went to a 6mm pinch bolt and an 18x53mm shaft. The torque required to seal the pinch bolts put the 5mm bolt in the plastic deformation range. All these rocker shafts will be replaced with the newer type.

10) Note the FORGED rockers with internal bushing, showing decent wear. These were rebuilt but I'm not sure they got sufficient oiling. Also in 1967 the factory put three more holes in the cam spraybars for better lubrication.

11) Original Solex cams showing decent wear pattern, this was the only bad lobe. Cam choice TBD, see other thread.

Again, thanks to JC and all who have contributed, this was a great learning experience. As one oustanding mechanic and engine builder told me, "the engine tells you a story" when its torn down, that will help you when you build it back up. Many items that were are a mystery before are now clearly understood.

Stay tuned. . .
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Old 02-12-2007, 06:02 AM
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My cams and pistons looked similar to yours John. I ended-up sending the cams to John D., and I replaced my pistons with J E 's. Of course, seeing the pitting on my cams, I decided that I had no choice but to pull the spray bars. The previous owner appears to have gotten full-value from the sprockets. I'm glad to see you making progress, and I'm anxious to see how she'll go back together.
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Old 02-12-2007, 06:25 AM
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Thanks Jon! It was a very informative process. Half the time was spent tagging and bagging everything.

Next steps will to thorougly clean, inventory and inspect everything. I'll put up my master checklist when it's finished, but the big items are. . .

Case-- Oil bypass mod, SC oil pump, squirters
Crank-- Clean, measure journals, measure radii, magnaflux, micropolish, clean
Cylinders- Clean, measure with bore gauge.
Rods- disassemble, clean, check for straightness with surface plate/comparator gauge
Pistons-- conversation pieces. JE to suit bore diameter.

How do you like the JEs? Any noise on startup? What is the cylinder wall clearance?
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Old 02-12-2007, 06:47 AM
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John, If I remember correctly. clearance was .0025", but I'm not positive. I'll have to check the paperwork. I remember being alarmed about having too much clearance, but so far the engine runs very well, and no noise. I don't have enough miles to render an opinion beyond that. About 300 is all. In fact, even though it was recommended to go 500 before re-torque, I'll probably do it later this week along with the other service items. While my pistons were worn-out, as yours, I have not been able to discard them. Not sure why- Maybe the cost of new ones, maybe just the novelty of seeing a piston with the oil contorl ring in an odd place. I've tried several times, but my hand won't release them.... staying tuned-in.
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Old 02-12-2007, 07:55 AM
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Weird question: Why not regroove pistons for oversize rings?
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Old 02-12-2007, 08:07 AM
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Kenik, even if those pistons weren't severely scuffed, more modern piston designs have:

1) a reduced skirt area for lower friction, this is free HP
2) oil ring up next to the compression rings for better oil control
3) other features like double forced pin oilers, reinforced skirts, split oil return and advanced coatings both on the sides and top.

There is one other explanation for the broken rings, of course. . . DETONATION will break the rings like that, as has been posted here . . . once I have an opportunity to measure the ring grooves I should have a better sense of the root cause.
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Old 02-12-2007, 09:00 AM
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This is like reading my teardown notes, I had broken rings because the lands were were too large (PO also did a re-ring on mine in the early 90's). My bearings were discolored and blue in places, the material on the main bearings could be scraped off with my fingernail. I also had a 30% leak on all but on cylinder.

Good luck on your rebuild! I'm just about finsihed with mine, my mechanic is doing all of the hard work since I ran out of time. I can't wait to watch your progress.
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Old 02-12-2007, 09:02 AM
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I am lucky to have escaped. Note to anyone contemplating "helping" Mr. John Cramer. He treated me like a prisoner at a Siberian Gulag. Forced to work in a freezing quonset hut with no food or water for six straight hours, often with the risk of great injury to myself with inadequate safety equipment and tools. While Mr. Cramer read Wayne's rebuild book and snapped photos. Beware.
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Old 02-12-2007, 10:15 AM
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Nice thread John. How many miles were on the engine before teardown?
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Old 02-22-2007, 08:29 AM
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Nate, about 20,000 as far as I can tell.

The engine was rebuilt in 1982 by a race shop in southern lower Michigan. The receipts show that the cylinders were honed, rings replaced, rods reconditioned, rod journals ground (the rod bearing part number is for a .50mm under set). Obviously the rings were out of spec as they broke with no other obvious signs of detonation, e.g. no damage to the top compression ring land. They probably broke within 500 miles of the rebuild.

What is really interesting, for those considering their own engine rebuild, is how accurate at diagnosis the leakdown tests I performed turned out to be. Remember I said I found broken rings on all but the number four cylinder? These are the results from a leakdown I did back in April of 2005. . .

I 40%
II 12%
III 45%
IV 7%
V 45%
VI 45%



Clearly, the leakdown test was spot-on.

Leakdown Results 1966 911 Normal
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Old 02-22-2007, 09:07 AM
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Yeah but how carboned up were the valves? What was the source of the cylinder leakage?
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Old 02-22-2007, 12:06 PM
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The source of the cylinder leakage was through the breather. Also, when the engine was running there was a significant oil mist blowing from the breather hose. When I would disconnect it from the oil tank you would see copious airflow and smoke from the hose.

None of the valves was burned, no pie-shaped slices or valves locked open by carbon. I should be able to tell better when the heads are cleaned, but I was surprised to find all the valves in good shape.
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Old 02-22-2007, 12:09 PM
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Quote:
Originally posted by john_cramer
I'll put up my master checklist when it's finished, but the big items are. . .

Case-- Oil bypass mod, SC oil pump, squirters
Crank-- Clean, measure journals, measure radii, magnaflux, micropolish, clean
Cylinders- Clean, measure with bore gauge.
Rods- disassemble, clean, check for straightness with surface plate/comparator gauge
Pistons-- conversation pieces. JE to suit bore diameter.
Since you are in there already I'd also consider:

-Boat tail case (and since you are there consider installing pins also)

-Knife edge the crank

-Port heads
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Old 02-22-2007, 12:20 PM
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Not to knock you, Juan, but boat tail and knife-edge is really $$....good for a race motor, perhaps not really worth it on the street. I really think shuffle-pinning is a good idea, and if there's one out of the 3 that you should do, I would do shuffle-pinning first before windage mods..

John, interesting tear-down. Have you decided what configuration (bore & stroke ) you might run?
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Old 02-22-2007, 03:00 PM
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Gents, thank you for the suggestions. As I eventually came around to concluding on my very long thread 901/05 Thread , it is not possible to make too many improvements without making the engine no longer appear original. OK, that wasn't a grammatically correct sentence but you get the idea.

For example, running Mahle Nikasils makes the cylinder fins different. Upgrading to later 2,2 heads makes the casting numbers different. Many other performance-oriented changes would increase the power well beyond the 160 HP limit imposed by the lack of a front oil cooler, which itself is driven by originality.

The original title should have been, "How can I improve the performance of a perfectly stock-appearing engine?" But I have learned a great deal since it began.

I am concerned not merely with the cost of knife-edging, mooning, boat-tailing and the other "Kremer" mods but with the impact on the engine's longevity. Were this a 9,000 RPM Appendix K screamer motor with a two-race rebuild cycle and an $100K/season budget, you bet. Instead, this is an occasional use autocross and rally car that will be shown in local PCA concours events, the Parade, and driven to the ALMS races in the summertime. A perfectly fitting mission for a true SWB classic: not afraid to be driven, but with reasonable limits on use designed to preserve originality for the next generation to enjoy.

Anyway, once I mic the crank and bore-gauge the cylinders I'll be in a better position to make decisions. If the crank is kaput I may go to a 2,1; if the cylinders are already at 81mm from their 1982 boring, perhaps a 2,2; if both, perhaps a 2,4

Stay tuned: inspection specs will appear here.

And thanks for stopping by. Now Juan, about those race engine ideas, did I mention I have a 2,2E race car with every suspension mod known to man and dual 911R coolers?
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Old 02-22-2007, 03:47 PM
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Very cool .
This thread makes me want to crack open my engine.

Thanks for documenting the work and please keep 'em coming.

John
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Old 02-22-2007, 05:23 PM
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No worries Scott, I was just trying to address areas where John could get longevity (pins) and power (albeit minimal increases) but in his original program he wanted to rev it to 7K safely but due to the non oil cooler issue I wanted to give him some "internal" mods that should yield some returns. As to cost, well you are correct my friend!

Now John, the 2.2..... that's the subject of a different thread altogether...
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Old 02-22-2007, 05:42 PM
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Quote:
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Now John, the 2.2..... that's the subject of a different thread altogether...

I know - I tried muscling in on John C's thread but I guess I will have to start my own.

John F
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Old 02-22-2007, 05:47 PM
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