Could there be a 2.6L based on a 2.2L

[RichHawk]

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

[Flieger]

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.

[RichHawk]

Originally Posted by Flieger

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.

Yep that would get to 2.6L 2632cc to be exact. Sheesh what a monster that would be if properly set up!

What size is the biggest bore before the cylinder bases need modified to clear the case thru bolts on a 2.2L?

Richard

[356RS]

I built a 66 X 93 mag case to get a 2.7 short stroke MFI engine. Cylinders were from LN Engineering.

[Walt Fricke]

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.

[RichHawk]

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.

Bringing home a 71 Friday

Here are pics of the engine.

Please advise what I can do without teardown to figure out what is in this thing..




Thanks,
Richard

[Walt Fricke]

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:



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.

[Walt Fricke]

Well, my marking on the photo didn't work out. I marked the center rocker as being somewhat odd in appearance.

[RichHawk]

Originally Posted by Walt Fricke

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.

How do you plan to measure displacement? You could do so directly, by measuring how much Marvel Mystery Oil you can pour in. Y

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.

Thanks Walt, all good thoughts.

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

[Walt Fricke]

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.

[Flieger]

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?

[RichHawk]

Originally Posted by Walt Fricke

Well, my marking on the photo didn't work out. I marked the center rocker as being somewhat odd in appearance.

Yep the center one looks just like the newer style rockers in the 3.2L I built for my 1987.

[RichHawk]

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

[RichHawk]

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.




Calipers are resting on the exhaust manifold stud, making the calipers appear wider than the port. it's an optical illusion.

[RichHawk]

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

[gearheadgreg]

Awesome.

[andrew15]

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

[Walt Fricke]

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.

[RichHawk]

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..

[BURN-BROS]

The crank is a 2 liter


So it's a 2.5 with 90's

or a 2.6 with 92's