jesusno2 Posted January 3, 2011 Report Share Posted January 3, 2011 Its been some time since i messed with a l20b and im stumped this is a l20b does the cam timing look correct?? the engine runs (poorly) and it does not want to rev up. timing seems correct about 12 degrees at idle. it does advance to around 20 degrees or so. so i ask the ratsun l motor gods to shed some light on this. still unsure if this is a carb problem since I have a hitachi on it still, and those a almost impossible to troubleshoot. heres a pic Quote Link to comment
john510 Posted January 3, 2011 Report Share Posted January 3, 2011 If the piston is at TDC im guessing the cam timing is off by the way the sprocket looks. Quote Link to comment
nismo dr Posted January 3, 2011 Report Share Posted January 3, 2011 agreed, if thats 1 tdc, its off Quote Link to comment
jesusno2 Posted January 3, 2011 Author Report Share Posted January 3, 2011 Yea its tdc on the compression stroke. it seems like its off to me reving super slow Quote Link to comment
Sealik Posted January 3, 2011 Report Share Posted January 3, 2011 3 teeth out...?...on sprocket? Not knowing.....just a guess on the L Quote Link to comment
hang_510 Posted January 3, 2011 Report Share Posted January 3, 2011 agreed, if thats 1 tdc, its off 1/2 a link. Quote Link to comment
john510 Posted January 3, 2011 Report Share Posted January 3, 2011 The cam lobes for #1 cylinder should be pointing up exhaust about 2 oclock intake at 11 ,and that oval shaped hole in the cam sprocket should be farther to the left. Quote Link to comment
jesusno2 Posted January 3, 2011 Author Report Share Posted January 3, 2011 This is confusing with all these holes and ovals etc etc wtf happened to line the dots up!??? all the valves should be loose on tdc if the cam timing is correct right? 3 and 4 have some tight valves at tdc. Quote Link to comment
datzenmike Posted January 3, 2011 Report Share Posted January 3, 2011 At TDC cylinder 1 In and Ex should have clearance because both are closed. #4 is just about finished the exhaust stroke and has already begun the intake stroke so both are slightly open. (and tight) If at TDC look on the other side of the cam sprocket. There will be a notch at the very back top edge and a small horizontal etch mark on the cam thrust plate above it. The notch should be just slightly to the right of the line. This notch to line position determines if the cam is properly timed. I've never seen a three hole sprocket before. All are 4 or eight and you can look through one of the holes to check the notch position. On this one you will have to look over the top of it. This is the proper notch to etch mark alignment that assures perfect cam timing. Not the number of teeth or links. Links can stretch and sprocket teeth can wear and the notch will move to the left advancing the cam. So the answer is can't tell. Post a picture looking down onto the back of the sprocket showing the notch and etch line. Quote Link to comment
jesusno2 Posted January 3, 2011 Author Report Share Posted January 3, 2011 I'm gonna do that as soon as I get off work later today. I can,t hardly stand it, i was pulling my hair out trying to find info, I have a manual for a 720, but it does not show how to set up for a l20b, just how to take it off and put back on the same way. Quote Link to comment
jesusno2 Posted January 3, 2011 Author Report Share Posted January 3, 2011 Couldn't wait lol cam timing appears to be correct to me. I cant get a picture behind the cam sprocket but the groove it is just to the right. the dowel pin on the cam is in the #2 hole. that groove appears to be directly behind the #2 hole just lurkin in the shadow if my picture. This may still be a carb or ignition issue yet. It just acts like the timing is really slow. Quote Link to comment
banzai510(hainz) Posted January 3, 2011 Report Share Posted January 3, 2011 Unfortunatly you have one of those USA made cam sprokets that dont show the timming marks on the cam plate. Best to get a Jap made unit that has the muti holes or the 4 hole ones where you can see the V MARK ON BACK OF SPROCKET. my best guess that its off as the dowel would be more in the 12 o clock poistion. Your looks like its more to the right meaning your off a link or too. one way to make this work is iff you can still see the brite links on the cahin is line it up to that using the dimples on the sprocket and assume its correct. If L20 set to #2 position I assume the cam is running out of power in the top end????? http://www.guba.com/watch/3000024223/Hainz-Datsun-L-Series-Engine-01-Timing-Tare-down-and-Rebuild On your photo here. unless it rotated when you pulled the sproket off look like the dowel is too far to the right. it should be more in the up position. also the crank should always be at ZERO!!!!!!!!!!! Quote Link to comment
banzai510(hainz) Posted January 3, 2011 Report Share Posted January 3, 2011 Now if you dont have a chain with the brite links its going to be much harder to do as If you had one(brite link chain) or the sprocket where you can see the V mark in back ) you could get by doing to this to make sure its correct. You might have to pull the front cover to get this right but. I woulf find another sproket from someone use a wedge to hold the chain up and start over. with help from my vid or other poeple. Quote Link to comment
Sealik Posted January 3, 2011 Report Share Posted January 3, 2011 Half a section....1 tooth....? I would wedge the chain and rotate the sprocket 1 tooth CCW Quote Link to comment
Sealik Posted January 3, 2011 Report Share Posted January 3, 2011 That punch mark on the right of the cam gear should be 3 links above the head when the engine is at TDC...? That might only apply to the Z22/24....and the 'link' might be a section... :P Quote Link to comment
john510 Posted January 3, 2011 Report Share Posted January 3, 2011 If your #1 piston is at TDC then it appears your cam and sprocket are rotated to far clockwise.Its hard to tell from the picture but it looks like the cam lobe is at 3 oclock or so.Like hainz said it looks like the dowel hole is to far to the right,it should be straight up which means you need to wedge the chain and pull the sprocket off,rotate the cam conterclockwise looking from the front.you will have to move the chain on the sprocket also.Remember the piston must remain at TDC,use a screwdriver to verify the piston is all the way up.It definitely looks like somethings not right if your at TDC, fix that before you assume that something else isnt working right.You can have the ignition timing correct but if your cam timing is off it wont run right. Quote Link to comment
datzenmike Posted January 3, 2011 Report Share Posted January 3, 2011 The screwdriver will only indicate that the piston is rising. It won't be accurate enough to define precise TDC on the L series and aligning the timing mark and pointer scale is better. Compression stroke can be identified by looking at the cam lobes and having the Intake at ten and the Exhaust at two o'clock. It is essential to rotate clockwise up to TDC and stop without going past or slack will be introduced to the tension side of the chain. Yes the gear looks odd but lens curvature and camera angle can skew picture perspective, but looking at it now, it most definitely looks off.. The sprocket notch to etch line alignment governs overall. . Quote Link to comment
jesusno2 Posted January 3, 2011 Author Report Share Posted January 3, 2011 The motor is at tdc on compression in all the pictures shown it has not moved. I'm gonna wedge the chain tonight and pull the cam sprocket tonight and see where the mark is on the thrust plate. Theirs really no other way to know where the cam timing is set at seems to me. What a retarded setup if ya ask me. Quote Link to comment
jesusno2 Posted January 4, 2011 Author Report Share Posted January 4, 2011 FIXED!!! cam timing was 3 teeth off on the gear had to rotate the sprocket counter clockwise it actually runs fairly well even with the shitty hitachi. Quote Link to comment
Sealik Posted January 4, 2011 Report Share Posted January 4, 2011 3 teeth out...?...on sprocket? Not knowing.....just a guess on the L FIXED!!! cam timing was 3 teeth off on the gear had to rotate the sprocket counter clockwise it actually runs fairly well even with the shitty hitachi. Lucky first guess....I guess.... :D Quote Link to comment
jesusno2 Posted January 4, 2011 Author Report Share Posted January 4, 2011 Lucky first guess....I guess.... :D Yea no doubt! good call! I appreciate everyones help! I'll bring the beer at canby! Quote Link to comment
banzai510(hainz) Posted January 4, 2011 Report Share Posted January 4, 2011 YOu have a bad made cam sprocket. The inspection holes are in the wrong spot that is all. Otherwise this is a good set up and instructions thats were given. Like I said before you have a USA made cam sprocket and you cant see the timming marks. Quote Link to comment
datzenmike Posted January 4, 2011 Report Share Posted January 4, 2011 You're in Datsun heaven... get someone to send you a good one. You know what you're doing so change it and confirm the cam timing properly for power and economy. Quote Link to comment
john510 Posted January 4, 2011 Report Share Posted January 4, 2011 Alright,glad you got it figured out. Quote Link to comment
jesusno2 Posted January 4, 2011 Author Report Share Posted January 4, 2011 Its dead on now and this isn't my truck I'm just working on it for a fella named pinhole on here. Now just gotta get a NEW weber 32/36 and el ignition and this baby will be ready for the long haul! It does have a exhaust leak due to somebody stripping some bolts out on the exhaust manifold and the exhaust needs to be fixed so its not rattling on the torsion bar prolly be looking for a L16 style manifold of a cheap header to just get rid of the stove pipe style setup it has now Quote Link to comment
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