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Camshaft question


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New member here. I bought a 521 recently and have been lurking here and on the510realm. The wealth of information on these forums is incredible.


I've tried searching but found nothing definitive. If this has been discussed, I apologize in advance.


I know many of the l16, l18 and l20b parts are relatively interchangeable. What I haven't found is anything conclusive on is the difference in camshafts for these engine other than the l20b/SSS cams seam to be the most desirable.


I managed to find a 620 at a local yard with an l18 and W58 head. I spent a little time yesterday pulling the head with fingers crossed that it would have one of the mythical W58 closed chamber heads. Knowing that there are only a few known examples of the W58 in a closed chamber casting, I wasn't too disappointed when I got it off and it wasn't a peanut head. I decided not to leave empty-handed so I snagged the camshaft (figuring at the very least, it could be used as a core) and went on my way.


I read somewhere that L series camshafts are marked "A", "B" or "C" and that is sometimes the deciding factor on which one to choose. Can someone please explain the difference, if any, between the l16 and the l18 camshafts that I have - if one is better or more desirable.

Here are some pics of the two markings I found on the one I pulled from the l18 as a reference.



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W58s never came on L18s. W58 heads were used on all L20Bs from '78-'80.


U20 was an L20B cam.



My 620 FSM says the L16/18 cams are identical in every way. I thought the L16/18 cam had less lift than the L20B but my 620 FSM shows the same lift as all L20Bs at 0.413". The Haynes manual for the 510 L16 shows 0.393" lift. I guess IF they have the same lift then this just leaves valve timing events...




L16/18 intake opens 12 degrees before TDC.... L20B opens 16 before TDC

L16/18 intake closes 48 degrees after BDC...... L20B closes 52 after BDC


L16/18 exhaust opens 50 degrees before BDC.... L20B opens 54 degrees before BDC

L16/18 exhaust closes 26 degrees after TDC...... L20B closes 14 degrees after TDC


The L20B specs are from two car and one truck cam and they were the same.


You want the U20 cam from an L20B. Try to get the rockers and keep in order so they go back on the same lobe. If mixed don't worry about it.

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