The flywheel on my S1 4.2 has several markings on it… anyone know what they mean? Engine number is there then there’s two number 1s and a B one one side plus an arrow on the other side…
I’m guessing the B is about balancing but not sure what it indicates and maybe the arrow points to TDC if I can locate another arrow on the block someplace (any hints on where?). How about the two 1s?
John North
S1 4.2 Roadster
On a 3.4 block, there is a sight window in the bell housing with index marks and on a 3.8 block there is a corresponding arrow that lines up with this arrow for TDC. Both line up closely with the cam oil feed line. There is a punch Mark on my 4.2 block in the similar location. Might have added that myself. Doesn’t do much after you get the tranny mounted…
Out of interest…your flywheel looks like it takes the spring clutch plate and not the diaphragm type. is that correct?
I ask because I have had all sorts of issues trying to get the right clutch. I ordered a diaphragm as the mounting holes are on the flywheel, but like yours, they are not tapped. SNG only list a diaphragm against my 1966 S1 4.2 so I had to order a spring type from the 3.8 spares catalogue. This made me think that perhaps the flywheel had been changed in the past for an early one?
However, seeing yours gives me confidence I have the right flywheel and spring type clutch assy.
Is it a spring clutch assy?
I suspect the punch marks are from somebody balancing the flywheel post factory, or alternatively they are position marks for install of a co- balanced clutch pressure plate assembly. Looked at a flywheel off my 68 - it has same B and (unnecessary) timing arrow but no punch marks.
Doesn’t the arrow signify 10 degrees BEFORE TDC? If memory serves me, that’s the point where the timing light should flash.
On the Xk engines equipped with the bell housing timing view port the flywheel has an arrow for TDC and timing index numbers. Maybe somebody modified your 10 with a little chisel work. A little paint helps give you a better chance to actually read the numbers.
Yes, thank you Kris, that’s correct!
Mine is a diaphragm… the holes in the flywheel are tapped. I believe this is not the original clutch since I can find no balancing “B” mark on the diaphragm to match the flywheel, and the clutch disk is labelled “rebuilt”
John
Typically aftermarket clutch assemblies are balanced by the manufacturer - or you can have it done. There is no necessity to balance them with the flywheel - if fact it’s probably better not to because what if you have to change the clutch?
I was careful on mine to get the arrow in the right place for TDC, but it’s about a degree different from what I measured using a dial gauge on #6 before the head was put on. Am I wrong or is the bell housing / flywheel wrong?
Very tricky to get the average dial test indicator accurate to 1 degree around TDC/BDC. Better to us the double-slop method or set TDS by cylinders 2345 being the exact same depth, which will finalise the TDC setting on 1&6 more accurately if you have the tools. Easier with the head off, of course, but…
