L20b timing help

[GoonLuv]

Hi all, I’m stumped and could use your help. I am having a hell of a time figuring out the timing on my L20b.

 

First the specs.

L20b with electronic dizzy.

Dizzy is for a 79 620 and is new.

New timing chain set.

 

Timing set was installed using the #2 position.

Lined up the v notch on the cam sprocket and installed chain making sure the bright links are on the the #2 dimple on the cam and on the crank sprocket dimple. The distributor shaft is at the 11:28 position as expected with the skinny side toward the radiator.

 

First question.

When the notch on the cam sprocket is centered on the groove the timing mark on the crank pulley is at 10 degrees advance on the timing plate.

 

Should I adjust the crank to line up with 0 on the indicator? If so how? Remove cam gear and move it a tooth?

 

Second question.

This is the one that has me saying wtf. I have a timing light with adjustable advance. I have to set it at 60 degrees advance to get the crank pulley mark to 0 on the indicator.

 

Wtf is happening? It runs but I have to use both adjustments on the dizzy and go to max retard to get it to start.

 

I am new to Datsuns but know my way around an engine. I’ve read everything I can find and followed the recommendations I found. For the life of me I can not figure out what I’m doing wrong here.

 

Thanks in advance for your guidance.

[Doctor510]

I too have a 72 510  give me a shout/ I may be able to help...  Doc

[datzenmike]

Set TDC using the timing scale and the notch on the crank pulley.  You MUST only turn in a clockwise direction to set this. If you overshoot the mark back well up and re-try. May take a half dozen tries but you cannot back up to set TDC, only turn in a clockwise direction. This will keep all the chain slack on the passenger side and make the cam timing check accurate.

 

 

Once TDC is set....

 

1/ The V notch in the cam sprocket should be just under the line on the cam thrust plate behind it and just a tad to the right of it looking at it from the front. Cam number does not matter as long as you get this. L16s are set at #1 at the factory. L20B and Z series are set #2.

 

 

2/ Now check your distributor timing. Should be like this...

 

 

If timing the distributor requires turning to extremes maybe you have the wrong pedestal or see if the adjustment plate can be flipped upside down. In some cases this is what has happened, however you can drop the oil pump and re-position the drive spindle to (say) 11:35 and this moves the distributor rotor under one of the wires under the cap. Hopefully #1 but if not... this wire now becomes the #1 and the others follow counter clockwise 3, 4,and 2.

.

[GoonLuv]

Thanks Mike I will doublecheck everything this weekend and post my findings.

[distributorguy]

60 degrees advance at idle?  Cam is likely advanced 2 teeth.  

[datzenmike]

Then the sprocket will not line up at TDC in any of the three holes. Easy check.

 

[distributorguy]

Are you using the pedestal and clamp plate that come with that distributor, or a set from a different type distributor?  There are a couple options that sit in different positions, and if you mix and match parts you'll have a mess to sort out.    

 

The "mark in the window" deal finding cam position is BS, unless you're lucky enough to have a virgin engine with OEM timing chain set, a chain that's not stretched, and everything else is perfect.  Its "ballpark timing" at best.  You may be better off setting the cam so the intake centerline (max lift) is around 107 degrees.  It'll run if you're off a tooth or two, but it'll be miserable.  Plus, who knows if they made your pulley properly.  I have several here that failed that test.  

 

Anyone who uses the "mark in the window" way to set up a cam needs to print this out and stuff it in your shop manual:

http://www.cranecams.com/uploads/instructions/803_.pdf

[datzenmike]

Christ, it's good enough.... we aren't talking race engines here. Doesn't matter how worn the chain and sprockets are as long as you get the marks like the picture posted, then the crank and cam are timed relative to each other and you're good to go. You'll be within +/- 2 degrees no matter what, and a stock engine will run on that just fine. You will NEVER feel the difference.

 

If you have the time money and equipment you can time the cam perfectly but you will be splitting hairs with a laser.

[distributorguy]

The difference can easily be 10hp at the wheels, yes even on a stock engine.  

[datzenmike]

No. That would be 12 at the engine. Nissans are better made tolerances than that.

[Deleteme]

Probably not helpful but...

Make sure the cam timing sprocket isn't upside down.

Four stroke has four strokes, 1 of those strokes seems like TDC when installing the cam, and the cam could be in the wrong position.

 

I've not taken one of these apart so take it with some salt.

[datzenmike]

 Just look at the front 2 valves. If on the TDC on the compression stroke these two valves will be closed. Or look at the rotor position. It will be pointing to the #1 plug wire on the cap above it.

[distributorguy]

Split overlap looks an awful lot like both valves are closed so simply watch the 2nd valve open, then close, then bring the timing marks up to TDC.  That's your #1 TDC firing stroke.  

[Stoffregen Motorsports]

Split overlap has both of the #4 valves at about the same lift, which will be minimal (about .015" on a stock cam), so yes, they will both look closed.

[datzenmike]

Obviously I meant that the cam lobes would be in the upward or 10 and 2 positions. There's no way to mistake #1 TDC from the other that is 180 the other side with the cam lobes bearing on the rocker arms..

[Stoffregen Motorsports]

Using split overlap helps identify TDC. If one valve on #4 is open a lot more than the other, then you know the cam timing is not right, or your TDC pointer is off.

[GoonLuv]

Thanks to Rag10 the goon is running again. Turned out to be a bad distributor. Brand new reman unit defective right out of the box. Pissed I Spent months troubleshooting it but stoked it’s running again.

[racerx]

Made is China crap.

[banzai510(hainz)]

alwasy have a spare distributor and carb to troubel shoot

[Stoffregen Motorsports]

I've heard guys say that there's about a 40% chance those new units will work.

 

Live and learn. Glad you got it running.

[jcd0402]

Same thing happened to me. Good thing I found a remanufactured points dizy for $25. I just bought a chevy ignitor to swap it on to the electric one to see if that works, hopefully it does.