Suplexilicious Posted November 19, 2015 Report Share Posted November 19, 2015 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. Quote Link to comment
datzenmike Posted November 19, 2015 Report Share Posted November 19, 2015 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. 2 Quote Link to comment
Suplexilicious Posted November 19, 2015 Author Report Share Posted November 19, 2015 U20 was an L20B cam. You want the U20 cam from an L20B. That's good news...better than I was expecting. I'm not sure how I didn't pick up on the U20 thing earlier. Thanks datzenmike! Quote Link to comment
datzenmike Posted November 19, 2015 Report Share Posted November 19, 2015 Also the L20B cam has these square bumps on each side at halfway down the length. Quote Link to comment
Suplexilicious Posted November 19, 2015 Author Report Share Posted November 19, 2015 What are the bumps for? Quote Link to comment
Doctor510 Posted November 19, 2015 Report Share Posted November 19, 2015 What are the bumps for? Turning the cam to prevent you from using vice grips on the cam lobes! Quote Link to comment
banzai510(hainz) Posted November 19, 2015 Report Share Posted November 19, 2015 should have taken the whole head!!!!!!!!!!!!!!! think a W58 is L20 head. just buy a whole L20 and dont worry about the cam issue. I dont think its even worth it to swap out cams for 1 hp gain and risk screwing up the rocker arms and resetting them Quote Link to comment
Suplexilicious Posted November 19, 2015 Author Report Share Posted November 19, 2015 Looking at the cam I pulled, it's got both the bumps so I'll assume it's the L20B. Score. If I get time before all the Thanksgiving madness, maybe I'll swoop back down, snag the head and pull the short block. Quote Link to comment
datzenmike Posted November 20, 2015 Report Share Posted November 20, 2015 What are the bumps for? Turning the cam to prevent you from using vice grips on the cam lobes! Good (enough) answer. 1 Quote Link to comment
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