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A concerning timing issue.....


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Ok I have an l20b bored .030 over with an A87 open chambered head that has something around .040 taken off of it. I use an EI dizzy and a 32/36 weber everything else is fairly stock. My problem is when I set my timing to 10 deg btdc my 521 won't do anything past an idle. It basically wont run. So I set it back to 5 deg and it pings highest ive run is 3 deg btdc without pinging.


Now I know I have something messed up here but am not sure what it could be.


My timing light has some sort of adjustment knob on the back, im guessing it is for an advance? I keep it turned down to 0 as I am not sure how to use it.

My cam sprocket is on hole 2 and the notches line up, so I am pretty sure that is not the issue.

I do leave my vacuum advance line hooked up while i time the ignition.


My question is this, to time my l20b A) Should I leave my vacuum hooked up? If not does it just need to be unhooked and or pluged?

                                                        B) What should I do about that adjustment knob on the back of the gun when I am timing the motor?

                                                        C) If I am timing things correctly what could be my issue? Wrong timing plate?


Help would be much appreciated and Thank you.




CHanged dizzy from 200sx to l20b dizzy pinging worse at all timing settings


Using no ethonal added 92 octane petrol no change


Purchased better condition head from erichwaslike and am waiting for that to be shipped (hopfully it fixes things)


Is it posible to change cam timing to bleed off some compression? If so what way do I  turn the cam sprocket?


Is there a way to idendifty and match timing plate to block to crank pulley? Maybe they arent matched up?


I am out of ideas and am about to park this thing and using bicycle until I can figure this out.





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This isn't one of those distributors with an extra connector, is it?  The kind that when not hooked up to a matching EFI ECU cause an undesired many degrees retarded timing?


Anyhow, how do you know you're at 3 degrees?  How does it run then?  Only thing I can think of is the timing plate/crank notch isn't a matched set.  It shouldn't ping at 10 degrees, let alone at 5.

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Well its slightly past the midway point between 0 and 5 so I guesstimated 3. Will any l20b timing plate match up to any l20b crank pulley? I pulled the pulley and the plate off hte same motor at pick n pull, so I assume it should match. Are thre markings that would allow me to identify them to see if they are matching? or should I go and pull another set? It runs alright but honostly Ive only ever driven this l20b and thrashed l16's So I am not sure what alright is.

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There is no reason to remove the vacuum line to the vacuum advance as there is no vacuum advance at idle. Having said that..... if your throttle is turned up too high or some other reason, this may be enough to cause vacuum to be sensed at the vacuum port in the carb.


If you aren't sure pull the hose off.



The L20B should have a single notch on the rear of the back pulley and the timing plate should be a saw tooth plate on the fuel pump side of the motor.  The saw tooth tips should read 20,15,10,5, and 0 from bottom up with 0 at top.





Some (L16/18???) are under the dizzy and a single pointer with 5 notches on the pulley.

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yes if your timing light has a dial on the back of it, it is an advance timing light.  If you set dial to zero, then the timing pointer will point to your initial timing or static timing.  I have one of those dials ones and at first can be confusing. Newer versions and better are digital and will have RPM, Dwell, etc...back to timing light...did you set up the engine to TDC.  This should be first because sometimes, we end up timing the car with wrong reference point.  Not sure if your parts like crank pulley is for engine specific..for example I have an L18 now and I am using L16 crank pulley.  It would be better if I had a L18 crank pulley (one notch) with timing tab (sawtooth) vs L16 with 6 notches on crank pulley. It can mess you up.  1). not knowing about your timing light 2). setting timing and not on TDC and 3). Mismatch pulleys with timing tabs. Also you don't need to disconnect the vacuum.  For more info. on using timing lgith, Google model number with instructions and you will find how to instructions.  Good Luck, let us know what happened..

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My valve timing is correct and am on the second peg hole, the dizzy while it could be clocked a bit different does point to the #1 position so it works, im going to double check here in a bit on the timing plate but I pulled them from the same l20b in the wrecking yard. After reading this my best guess is what mike mentioned, too high of idle speed. If its not that then maybe my dizzy is fucked.

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Im stumped everything seems to be correct yet I cannot even begin to drive my truck with timing set to 10 deg btdc. I set my idle speed as low as it could go without dieing (basically backed out the idle screw all the way then back in some as it would just die with that idle screw all the way out. I took the vacuum hose off then set my timing then tuned the carb and got the same results. Anything I could be lokking for to check if the Dizzy is bad? Also shouldnt my car idle and not die even though the idle screw is backed all the way out? Or is it normal to do that?

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If idle mixture is all da way then too rich or jet is too small. You should be able to turn screw in and when it starts to die, back off and listen for idle climb and should smooth out. While your doing this your idle speed screw should not be messed with till idle mixture is dialed in. Have you checked your valves lash adjustment.

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Check your marks, put your motor at tdc and make sure your marks line up. Idle too high, advanced hooked up will both cause you too set timing too low not high. Your problem is high timing therefore those issues don't concern you. Your problem is timing marks or light.

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What ssnapz said.  Especially this part.

"Check your marks, put your motor at tdc and make sure your marks line up"


Almost every engine I have worked on runs with about 10 degrees of spark advance, that is 10 degrees before top dead center.

If your engine does not, something is wrong with the timing marks.   It might be the crankshaft pulley, and the timing chain cover are off two different engines, and that is messing you up.


On inline four cylinder engines, you can sometimes feel TDC, because at TDC #1, and #4 are at TDC, and #2, and #3 are at BDC, so at that point in the engines rotation, the crankshaft will turn easier, for a few degrees, because the pistons are not moving.  If you can feel this, compare it to what the timing marks are indicating for TDC.   If you cannot feel this you might have to loosen and possibly remove rocker arms from the head, to eliminate camshaft drag on open valves.


Another way to check TDC is to remove the crankshaft pulley.  The keyway should be pointing exactly at the center of the camshaft.

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I think hes talking about the idle speed screw being out all the way and it still idles. Thats OK. to 1.5 turns IN ingagment.


if your sure your timming marks are fine and set to number 2.

Rotor points to #1 it should work. valave lash Ok

Is the dizzy timming plate in the center???? no xcranked to one side to get this 10 deg BTDC timming?

If center I wouls assume this is all OK and you got a carb proplems or maybe a wrong coil install?

Im just doing a rought guess right now.




accel pump work in carb?


I dont know how to use a Adjustable timming light . I assume you put knob to 10 then you dial to it.

I just use a normal timming light and look at the crank markings and this will tell my if Im off alot. to maybe even a tooth off on the dizzy/oil spindal.

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Ok here are my pics of things, to start off I approximated tdc based on the end of the compression stroke (cyclinder 1 cam lobes in a V shape) then gently held a screwdriver in the spark plug hole and wiggled the crank back and forth until i was absolute tdc.


First off my timing plate/crank pulley


It is tough to see but it is lined up exactly


Here is my cam timing


I think this is correct but say something if I am wrong


Here is my Dizzy


While the Dizzy is clocked nearly all the way counter clockwise it can go far enough to get me to like 20 deg btdc right now I am at 3. So it is def off a bit but does that make a difference?


Finally here is a video of the slop in my dizzy/dizzy shaft I have suspected this as a problem issue for awhile but cannot get a confirmation of any sort.


The whole dizzy wiggles by hand even  though all bolts are tight and when running it wiggles as well.

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when you said you are on TDC...where did the dist rotor point to?  should be pointting to #1 spark plug.


 And your cam lobe, you will have to take valve cover off, what direction.  Looking from front of engine, the Ist cam lobe should be at about 2 oclock and 2nd one at about 10 oclock.  You can use a screw driver and put it in the # 1 spark plug hole and  slowly turn your crank with a socker (clockwise) but not as accurate as a TDC stopper tool.  See here:  http://www.amazon.com/Competition-Cams-4795-Center-Bolt-Style/dp/B000CIOA0Q/ref=sr_1_fkmr1_3?ie=UTF8&qid=1360715300&sr=8-3-fkmr1&keywords=TDC+stopper+tool.


Some people just put thier finger on #1 spark plug hole and feel for air, some people put toilet paper and when it pops out then you know you are close to TDC.  Either of these methods will work.  I think the TDC stopper is the most accurate....then use your timing light to verify/set. 


BTW I don't think your dist. should not be wiggling.

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