Flywheel 180° Out

Dear therapy group, I mean, ... Dear Sir's, Ha! Ha! just a note: Remember that a Jag engine is different from most other engines. The number six cylinder as they call out in the manual is actually the cylinder closest to the radiator. So as I understand it, with the front cylinder @ top dead center, your timing marks should line up and the brass tip of the distributor rotor should be right under the wire connected to the front cylinder ( number 6) ( closest to the radiator). Yes? No? - Edgar Blake

..AND both valves should be closed. - Mike Eck

The #1 piston will also be TDC. True TDC is determined by the cams. - George Badger

Hi, Edgar -

What you said is true IF and ONLY IF the engine was properly assembled, with the CAMSHAFTS in correct relationship with the crankshaft; that is, with both camshaft lobes for the front cylinder pointing toward the outside of the engine (top of the compression stroke, just before the start of the power stroke). As I can attest to from personal experience (my first engine reassembly; I'm not proud) it's easy to assume that number one cylinder is at the front of the car and proceed accordingly! Everything lines up, but the distributor's 180 degrees out of phase! First thought was to remove the head, rotate the crank once, and reinstall, but I did not have a spare head gasket then; second thought was to loosten the distributor and rotate it 180 degrees, but the vacuum pipe wouldn't reach or dress properly (this was in 1965, I think, in a 1955 XK-140 MC-ww DHC). My soon-to-become BW suggested that I just exchange the distributor wires across the distributor cap!! Problem solved! No mechanical damage (I raced the car in club racing for a couple of years thereafter). Just be aware, with a Jaguar, anything can happen and usually does (why do you think Sir William included those neat, complete tool kits?)! Best of luck! - Larry Schear, Twin Cam, Inc.

I have to agree with Mr. Jim Warren, gas pedal function will be reversed but another little known side-effect of having one's XK flywheel on 180 deg. out is that the windshield wiper arms will function 180 deg. out of synch from each other, one there for Mr. Martin Jacobsen to consider perhaps. - John Morgan

I guess that I have to reply to the 180 degree out flywheel comments. The flywheel can be put on the car in two positions. 0 degrees and 180 degrees are the two positions. The timimg mark on the flywheel would show up as either a TDC or BDC for the 1 and 6 cylinders. If the clutch/flywheel assembly is balnced properly (This is the key!), it doesn't matter to the motor if the flywheel is mounted in either of the two positions. It does matter if the flywheel mark is used for timing purposes. I have seen several cars with the 180 degree mounted flywheel with no other ill effects to running. One reason for a flywheel being mounted at the 180 degree point is the starter teeth wear. Generally when a Jaguar motor is turned off, the motor will stop a one of three spots. If a worn flywheel is inspected, you can easily see the three spots. With worn teeth on the flywheel at the initial mesh point between the starter and flywheel, the starter may not engage or engage roughly doing more damage. Rotating the flywheel places a different set of three spots as the initial starting point for the starter. This was a cheap way back in the 70s and 80s to fix a car that had a starter engagement problem. Its not doing the repair properly, but that is the history of a lot of the 180 degree rotated flywheels! Another reason: It would also show that the mechanic changing a clutch probably did not research the car or did't care about the position of the flywheel when reinstalling. - Cleo Bay, XK120 OTS, XK140 OTS, E-Type OTS, S-Type 3.4

George, early XK engines like mine have the TDC timing mark on the flywheel, nothing at all on the damper. Bill, Page B29 in the manual certainly leads me to believe it is possible to put the flywheel on 180 degrees out, at least on the early engines. But if you then timed it according to this erroneous mark, the engine would probably never start. But going back to Rob C's overheating 140, he didn't mention whether his timing marks are on the flywheel or on the damper, but either way, I seem to remember his car was running good, and then suddenly started this overheating, so we're not looking for something wierd like flywheel out of phase. Rob, I don't think your heater hose flow routing is it either since you haven't changed it. Better to think about removing the intake manifold and look for blockages, then you can get a better look at those core plugs on the RH side of the block and decide if you want to try tackling them. You might be able to solve this without pulling off the head. Has anybody removed the three hex socket core plugs in the head valley between the spark plugs, any experience to relate? And just to cheer you up, Rob, the other day I found a 1959 Perfect Circle calendar in an antique shop, and the picture on it was of a light blue XK140FHC with body color wires, black drums and wide whitewalls on a mountain road above the tree line. The bonnet is up, there are two guys staring at the engine, and there is a pickup truck in front with an open toolbox on the tailgate. This shot just begs for a caption, and couldn't we write a million of 'em! How about "Yeah, Jake, these furrin cars have a special radiator hose that closes up automatically to keep it from running too cool on mountain passes." - Rob Reilly

I've noted the timing marks (arrow) on 120 flywheels (as commented on by Rob Reilly) but not on 150 units. On the 120, the arrow aligns with the index line on the bell housing at the small hole to give you a TDC reading. On my 150s, I use the pointer on the sump and the notch in the crankshaft damper to get TDC. I have also noted on some dampers (150 and MK II) that two punch marks have been made on the outside surface for reference.

As I've rebuilt XK engines in the past, I use all available references. At the bench or engine stand area I'll have three or four manuals and guides open as I carefully reassemble. While I feel comfortable in building these engines, I don't want anything to go wrong as my memory for detail isn't as great as it used to be. So, I am constantly reading and checking my references. For me there are critical alignments of moving parts, e.g., 1) the distributor shaft (ensuring that the offset of the notch is positioned properly); 2) the crankshaft is rotated to TDC (#1 and #6 pistons are positioned right: I use a straight edge across the block, then check the arrow or damper pointer in relation to the index mark); 3) flywheel positioned properly, i.e., the arrow lines up with the bell housing mark if a 120. This is only for looks since it can be 180 degrees away from the factory mounting point and still function properly. Cleo Bay provided good comments on the rationale for moving the flywheel around. It has to do with flywheel teeth wear. 4) proper installation of the camshafts. By this I mean installing the intake camshaft on the intake side of the cylinder head and the exhaust on the exhaust side. On my first head build I reversed the position of the camshafts in the head. No fouling (contact of the valve with the piston) occured but, folks, they won't run this way. Fortunately my mechanic friend determined why my newly rebuilt engine would not run. He reversed the camshafts and the engine immediately started. What a lesson! 5) phasing of the camshafts with the crankshaft. While I made a mistake in installing the camshafts in the wrong place on my first rebuild, I have not installed the camshafts out of phase. I have been very, very conscious of this. This is the big no no that all the books warn about you join the head to the block. Anyway, I make certain the engine and head are properly "phased" before they are joined as an engine. Through use of the camshaft timing gauge I ensure that the camshaft notches are 90 degrees to the face of camshaft cover seat and the crankshaft is positioned at TDC. Attention to these critical areas have worked well for me in the past. My only engine failure to date was caused by a dropped valve. The lesson for me was that I will not reuse old valves. Luckily, the valve stem and head separated with the engine at idle. So damage was confined to that combustion chamber. It was rewelded and works as new once again. - Bob Oates

Rob, You are correct about early XK engines. A real minority. And your second statement is why they changed. Too many untrained mechanics, read american, were working on the cars and did not understand the subtle differences between chevies and them little furrin cars. I have removed the hex socket core plugs in the cylinder head and found there was no reason to. Very difficult job. - George Badger

If you have any questions or comments send e-mail to: ted@jag-lovers.org
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