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Could there be a 2.6L based on a 2.2L
I'm going to pick up a 71 tomorrow, engine is out, and was in stages of re-build into something better than the 2.2 that it was. It's alway fun to speculate, but I can't fit the pieces I've been given into one concise picture.
After being mostly buttoned down, the project got shoved away and stored in a garage for 25 years. History became legend. Legend became myth. And for two and a half decades, the engine passed out of all knowledge. Which is a Lord of the Rings way of saying that the details of what have been done are long lost. The Engine builder that knew all that was being done has died. The owner remembers a few details worth mentioning on the engine rebuild: 2.2 was pulled because it jumped time. Bigger pistons and Cylinders were installed. The Pistons were fly cut to make clearance for the valves S cams were installed (Heads are unknown) He remembers the new displacement as 2.6L Now I can't figure out 2.6L But I can make 2.5 SS fit most of those pieces of the puzzle. Of course the cams and Heads could be S cams and heads together. How would I be able to identify S Heads without disassembly? Or they could be the stock 911T heads rebuilt, but with some big unknown cams. All in all, it's going to be a fun Mystery to solve. Thoughts? Help Identifying valuable parts? Wild A$$ speculation on what I'll REALLY find when I get there? Thanks, Richard http://forums.pelicanparts.com/uploa...1323271930.jpg |
Maybe it is 92mm cylinders from an RSR 3.0 with a 66mm stroke. I have not done the math yet but maybe that is 2.6 liters after rounding.
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What size is the biggest bore before the cylinder bases need modified to clear the case thru bolts on a 2.2L? Richard |
I built a 66 X 93 mag case to get a 2.7 short stroke MFI engine. Cylinders were from LN Engineering.
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3.0 RSR cylinders won't fit. They are 95mm anyway, which would make a 2.8 with a 66mm crank.
A 92mm 2.8 RSR cylinder would fit, though. There was also a 91mm cylinder. 25 years ago we didn't have Nickies or J&E, though there were other makers of pistons around. |
I have the engine and car home. From the numbers the cases look to be from a 1969 911T. It will be next weekend before I'm able to do any in depth study of the engine, like measuring the volume of one cylinder at BDC, or measure the lift of the valves.
So far I've been just cleaning up the car itself, and trying to figure the value if I decide to flip it instead of putting it back together. http://forums.pelicanparts.com/porsche-marketplace-discussion/643628-bringing-home-71-friday.html Here are pics of the engine. Please advise what I can do without teardown to figure out what is in this thing.. http://forums.pelicanparts.com/uploa...1323545296.jpg http://forums.pelicanparts.com/uploa...1323545307.jpg http://forums.pelicanparts.com/uploa...1323545322.jpg Thanks, Richardhttp://forums.pelicanparts.com/uploa...1323545424.jpg |
Intake and exhaust port diameters in millimeters, please.
Are the heads twin plugged? Pull the vertical (from the bottom of the case) oil pressure regulator plug and take a picture of the spring, piston, and other parts you find in there. From your photo it looks like not all of the rockers are of the same type: http://forums.pelicanparts.com/uploa...1323547334.jpg The kind of rocker shafts a guy wants should have 6mm diameter pinch bolts, and one end of the shaft should be flush with the housing where it is fastened. The housing has a thick side and a thin side, and it is the thin side where the shaft end is flush. I'd pull a rocker or two to see what you have. Especially to check to see if all rockers have brass bushings. How do you plan to measure displacement? You could do so directly, by measuring how much Marvel Mystery Oil you can pour in. You'd measure what it takes to fill everything (including the cylinder head)at TDC for the cylinder chosen, and then what more it takes when you rotate the crank down to BDC. You'd want to pull both valve rockers before doing this. From the results you can calculate the displacement, and as a bonus the compression ratio. Calls for careful measuring, though, with radings at least as good as one cc. The cylinders should have some casting/stamping markings around their bases. Those might (or might not) provide clues. The cylinders look to be aluminum. Izzat so? You have the desireable early exhaust manifolds. If you can borrow a boresocpe, you might be able to look inside the engine for some clues: is the crank counterweighted or not? Cast or forged? Knife edged? What rods? (Probably not Carillos, but you never know). And what letters/numbers are cast into the underside of the pistons? I've not tried this, but just maybe, by removing the oil sump pan (if it has the removeable screen), to measure the crank throw. Likely choices are 66mm or 70.4mm. Is the flywheel held on to the crank with six bolts? But for a barn find, that motor is a whole lot more appealing looking than the sad car. |
Well, my marking on the photo didn't work out. I marked the center rocker as being somewhat odd in appearance.
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What am I looking for once I pull the oil pressure regulator? Yep Marvel Mystery oil is my plan for the displacement trick. No need to remove rockers, just be sure it's on the compression stroke. I'll loosen the rocker adjusters just to be sure. I figure to measure the stroke directly with a feeler wire down the plug hole. Measure how far the wire moves up and down. Viola! Stroke. Of course this only works if I can hold the wire parallel to the bore. Richard |
You can tell by the lenght of the spring in the vertical oil pressure system, and by the piston in both the vertical and horizontal, whether the oil pressure modification has been made. Any motor done after about 1977 should have had this simple modification made to it, at least for high performance purposes. If you don't have Anderson or Dempsey's books to look at pictures of this, just post one.
I am dubious about coming up with an accurate measurement of stroke in this way, given where the spark plug holes are located. I have wondered if one could compensate for this by purposely placing the measuring rod into one "corner" of the piston/cylinder interface, and using trig to compensate for measuring a hypotenuse. I have also thought that perhaps a plastic knitting needle might be appropriate for this purpose, as being unlikely to scratch anything. But maybe I worry too much. I think of these things in terms of measuring other people's race engines to insure they are within the rules. One would want to test such a system on a motor of known dimensions before trusting it. Pulling a head off would allow you to represent accurately the bore and stroke, as well as the valve sizes. Is a fair amount of work, though with a clean engine not such a hassle. |
It looks like 5 out of 6 rocker arms on that side are the early forged type? They have an adjustment screw though. Wasn't that for the early engines while the 906 used forged rocker arms with shim valve clearance adjustment?
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I measured some things, and got numbers off everything.
Heads: Single plug 36mm intake 33mm exhaust ports directly at the heads New Valves and guides Heads Part number 911.104.306.0R Cylinders have these numbers cast in at the base: 907N9 W3 - CORRECTION - the casting reads 90ZN2 W3 (bottoms were shaved off) Stamped in they have a "M" symbol (Mahle?) with 714 above and 083 below Height mark 5 there are 11 fins, that are curved on top and bottom and the head bolts run through the fins. I'm not sure what the cylinders are, and I forgot to do the magnet test, but they look aluminum. Crank to flywheel is a 6 bolt 65mm diameter end. Cases are from a 69 911T so says the engine SN 6195950 What do we have for heads? Thanks, Richard http://forums.pelicanparts.com/uploa...1323574907.jpg http://forums.pelicanparts.com/uploa...1323575063.jpg http://forums.pelicanparts.com/uploa...1323575170.jpg http://forums.pelicanparts.com/uploa...1323575225.jpg |
Ported? If so then for what?
From Wayne's book, I can't find any stock heads that match these port diameters 36mm intake and 33mm Exhaust? It was so odd, that I went and double checked it again. Then I went and double checked the calipers were not lying to me. Sure enough the intakes are 36mm and are carburated (no MFI hole) Too bad I didn't get any carbs. The closest I got were six jets. So they have to be ported, which supports the claim of a set of hot cams. Now I gotta go map the cam lift, angles and duration. http://forums.pelicanparts.com/uploa...1323577243.jpg Calipers are resting on the exhaust manifold stud, making the calipers appear wider than the port. it's an optical illusion. http://forums.pelicanparts.com/uploa...1323577401.jpg |
OHH it might just be a 2.5 SS !!!
So now I'm a bit excited!
90mm cylinders, Ported out 2.2L heads, and 2.2L cases. If the crank is still 66mm, then I got myself a 2.5L SS!! now I gotta get a bore scope into the plug hole to see the pistons. Gotta do a CR check. Gotta map the cams, Probably worth taking the timing chain covers off to see the cam part numbers ans see if there is an aftermarket grind to them. Fun Fun!!! Richard |
Awesome.
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See if you can get a bore scope up through the oil sump plate opening and try to read the casting number on the bottom of a piston. If I recall correctly, my OEM 92mm RSR P&Cs had the same 90ZN casting numbers on them as well, so your engine may in fact have 92mm which would give you the 2.6L displacement.
As well, it looks like someone went to the effort of finding and fitting the early forged rockers, porting the heads, later oil tensioner setup, etc - finding the 92mm setup wouldn't suprise me at all. Regards, AM |
Perusing Anderson's table, the only heads with 36/33mm ports stock were some of the 1969 MFI motors. But from the casting date, these were cast in '70, most likely for a '71 motor (same difference, though).
The '70-71 E and S motors were MFI, but these heads aren't drilled for that. So most likely they are T heads (32/32 port size) which have been bored out. You should be able to see that machine work. Valves most likely 46/40, which was the standard size for all street 911 motors from '70 through the 2.7s up through '77. The S ports for the 2.2s were 36/35, and for the 2.4s were 36/36. So these have for sure been ported, as you and others have noted. |
Interesting things found
While digging through all the parts everything, I found the following interesting things.
Two brand new 40mm valves. I opened the packages myself. I found the one forged rocker that was missing. The adjuster was messed up from some ham fisted screwdriving monkey, so they replaced it with the modern version of the same. and my favorite, the two pull pins that come with Carrera tensioners. Which means the tensioners are likely brand new. Well brand new, never used 31 years ago.. http://forums.pelicanparts.com/uploa...1323732835.jpg |
The crank is a 2 liter
So it's a 2.5 with 90's or a 2.6 with 92's |
Aaron
How do the pictures and dimensions of a 66mm six bolt crank distinguish it from a 70.4mm 6 bolt crank? Walt |
The flywheel end of the crank has aluminum plugs.
2.0/2.2 have 2 plugs 2.4/2.7 have 1 plug However you cannot tell if the crank is counterweighted. Odds are it is not based on the engine being a T. |
She turns over using a lever arm against the flywheel bolts! I soaked the rings in Marvel Mystery oil for an hour each side.
Now one side gets to soak for days. I'll have to wait till this weekend to open up the sump and see idf I can determine counterweight or borescope of piston innards. Going out of town for business (damn the day job). More to come this weekend! Richard |
Thwarted!
So close! yet so far.
Is this screen original? It sure does a great job of keeping the borescope from being able to bend around and see the underside of a piston :( I did my best to angle the bore scope to get shots of the pistons themselves through the plug holes, but the bore scope head is too big to actually fit through the plug hole. The pistons inside are rough surface texture, and you can see the machine work where someone did indeed fly cut the pistons for valve clearance. Can anyone identify the pistons? I guess it's volume checking time. one cc at a time :) http://forums.pelicanparts.com/uploa...1324069284.jpg http://forums.pelicanparts.com/uploa...1324069293.jpg http://forums.pelicanparts.com/uploa...1324069301.jpg |
Richard
Bummer. Early cases had that screen. I think it got supplanted by a much finer mesh screen which surrounded the area from which the pump sucked. Later pumps had a screen with what looks like the early screen's mesh size permanently attached to the pump suction intake. Race motor builders using early cases typically discard the screen which is in your engine and use the later style of screen or screens that attach to the suction tube. Or did you remove a screen with the sump plate and so on? That would make sense, since the screen dividing the engine into upper and lower areas wouldn't catch debris from the valve and rocker area - like an adjuster nut which came loose and got through the return tubes. I'd say that this motor was not built with a later oil pump. Certainly not something really nice, like a 930 pump. Though in that case you would need a medical grade of small diameter laparoscope or the like to get around its permanent screen and upper plate. |
Walt,
Yes I did remove the sump pickup fine screen with the sump plate. and though you are right, I cant get anything past the coarse upper / lower screen, I did creatively put a flashlight right down onto the coarse mesh screen, and was able to illuminate a piston skirt and could actually read some numbers!! Though I can't read them very well. One side of the piston skirt definitely reads Mahle the other side there is a 5 digit "number" though what I guessed it to read didn't come up in the pelican search or a google search. My best guess is that it says 82106. |
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which at least one pelican thread says are 2.7L 8.5:1 CR pistons 90mm diameter. Which in turn, TaDa! says 2.5L SS motor!!! http://forums.pelicanparts.com/911-engine-rebuilding-forum/406641-mahle-90l61-pistons-what-they.html Though that CR won't be right with my ported and possibly modded 2.2 heads with these pistons. where's my pippet! gonna fill up a cylinder today and answer the displacement and CR once and for all! |
Playing around today, I did a leakdown on the 69 engine that I believe is a 2.5L SS
Leakdown was about as you would expect for a newly rebuilt engine. Cylinder % leakdown 1 5% 2 2% 3 4% 4 5% 5 2% 6 10% out the exhaust I suspect that # 6 exhaust valve was open for 31 years and forms a patina of surface rust, and therefore didn't seal as well as the other ones. I took a timing cover off to see if I could read any numbers off the cams. Nope, no numbers stamped on the end of the cams. Darn. Tomorrow I'll check the CR if I'm lucky. |
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93mm pistons??
I measured everything three times, and I keep coming up with 93mm Diameter pistons, and 66mm stroke.
Here's the method I used: Measures stroke with two "tools" measuring the distance change from TDC to BDC Both of them measured 66mm repeatedly, even though the tool was down through the spark plug hole, and at an angle to the piston. Tool 1 was a 1/4" diameter plastic dowel I marked it at TCD relative to the cam carrier, then marked it again at BDC. Measured 66mm with about 1mm error. Then just for fun, I used a 1/32" diameter steel cable (Think bicycle brake cable) and held it up against the cam carrier while rotating to BDC. 66mm again. Volume. I mixed kerosene and Auto transmission fluid together and poured it in the cylinder at TCD to find the combustion chamber volume I got 70cc once I perfected the method. I then measured at BDC, and repeatedly got 520cc of total volume. 520cc minus the 70cc gives 450cc cylinder swept volume. 450cc =Pi x R^2 x Stroke gives a radius of 46.5mm = 93mm diameter Additionally the 520cc total volume divided by 70cc at TDC gives a whopping 7.5:1 CR So recap. I think I have a 66mm stroke 93mm diameter 2.7L engine with a whopping 7.5:1 CR Oh and the cams are S type cams... Thoughts? |
Spark plug takes up some volume. Did you account for that?
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Richard |
here are the cam measurements, taken directly at the valve, and duration angles are crank shaft measurement angles
at 1mm lift: Intake / Exhaust 256 deg / 243 deg Duration .444" / .403" lift at .050" lift 248 deg /237 deg duration The closest I can come to making these match is early S type cams. Anyone know of other cams that would have been available 30 years ago that might fit these numbers? |
Well, the 66mm fits with what Aaron told us - from the end of the crank you can tell if it started life as a 66 or a 70.4mm crank. This is a 66, it seems unlikely that it would have been ground to get some other dimension, and that fits nicely with your measurements.
Despite the obstacles, did your borescope allow you to see part of the crank to determine if it was counterweighted or not? Hard to say if CW is good or bad - some like the non CW crank because of its smaller MOI for race motors. The CR calculations and swept volume calculations do fall nicely into a possible cylinder diameter - 93mm. There are flies in this ointment. 1) Although Mahle did (per Anderson) make a 93mm P&C, it was pretty rare I think. Used by SCCA GT2 racers with 914s (1mm overbore allowance for the allowed 2.8). SCCA did not allow twin plugging these race motors back when, and apparently this isn't twin plugged, so that does fit. 2) But the CR - who would build such a motor with such a low CR? 70ccs is the upper limit of what Anderson cites for 2.7 heads he had measured. But your measurement includes the effect of the piston dome, suggesting (assuming there is a dome) that the head volume is rather larger than this, which doesn't make a lot of sense. And 7.5 CR? Would not be a snappy motor. 3) Then there are those numbers cast inside the pistons, which seemed to indicate a 2.7 CIS piston? Your bore scope through the plug hole ought to let you determine if the pistons are for CIS (which means they are 90mm max), or something fancier, like RS MFI or RSR pistons. All of which casts some doubt on the displacement determination. I am hardly expert in the use of a burette for measuring, but I did have the ability to grease around the piston top circumference to try to keep leakage to a minimum. I used Marvel Mystery Oil (everyone should have this stuff in his garage, if only for the name) on the recommendation of a local shop. I got readings which I believed, then wondered how to get the stuff out without making a mess. I let it sit for some days. When I pulled the head off to swab it out, it was mostly gone! It had to have seeped by the rings (crappy old ones I installed just for this test) despite the grease, and spread out on the inner surfaces of the case rather than dripping out the open other side spigots. This was only enough for the cylinder filled heads, too. Encouraged by what CGarr did, though lacking his machining skills and machines, I took an old spark plug and bashed its innards out. I then inserted a clear plastic tube from the junk box into the hole and epoxied it in place. When filling through a spark plug hole I could fill until the fluid rose up into the tube where I could see it. I then marked that spot, removed the apparatus, and measured what it took to fill just the tube to the line. Next time around I measured first so I could draw a line, and filled to the line. So not too hard to account for the spark plug hole one way or another. Anderson says he has measured 2.7 heads at between 66 and 70cc, with the RSR head at 76cc. He notes that putting Euro Carrera 2.7 (RS) 90mm pistons on a 66mm crank would give a calculated 7:1 CR, though machining the heads could bring that up to 7.5:1. Too bad that unnecessary stock screen is there, because maybe the difference in cylinder spigot wall thickness between 90mm cylinders and 93mms is something you can tell just by looking if you know what one or the other ought to look like. Anyway, the effort of 93mm Ps and Cs with that low a CR doesn't make sense outside of a turbo. |
That would make a helluva turbo engine!
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Or the other answer. I did a crappy job measuring. Last thought. Someone (not me) is going to have to disassemble the heads and P&Cs for two reasons: 1)The Sheetmetal air guide tin was not installed between the cylinders. 2) the beveled thru case washers were not used when the larger cylinders were put on, so I fear the cylinders are resting on the washers and not sealing against the copper gasket. I have to punt. I could have convinced myself to keep the 71 If the engine was nearly bolt in ready. But the distraction level is too high. it's too easy to play guess the CR for hours instead of earning the daily bread. I'm going to sand down the primer surface rust on the car, re-prime and sell the 71 and engine either together or separately. :( |
AFAIK 2.2 and 2.7 combustion chambers are exactly the same, only difference is a chamfer on the 2.7 heads on the heads of squish area.
2.0 heads have deeper combustion chambers. |
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if so then I'll delete my completely misleading picture above. and then go back to scratching my head.. |
2.2 thru early 2.7 have identical combustion chambers and valve sizes. late 2.7 heads have a deeper spark plug recess and a chamfer. I do not remember what year the 2.7 changed but around 1975.
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2.0 liters are the ones with the deeper dome.
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