LZ Timing issue

[Jayroc]

Back story

L20B was running, pulled apart to for rebuild.

 

U67 head (assuming stock cam) cam sprocket was on #1 position. Every thing i read says this should only happen on a L16.

 

Every thing is back together new timing chain.  Set it at the #2 position.  I'm at TDC cam lobes are at 10 and 2.

 

Firing order is 1342

 

I did have a matchbox setup but i mislabeled wiring and cooked it. Now wired up as a HEI setup.

 

Lifters set at .008 and .010 cold

 

it trys to fire off and backfires though the carb weber 32/36

 

Am I missing anything 

Edited June 4 by Jayroc

[Jayroc]

 

 

 

 

 

 

 

 

[Jayroc]

 

 

[datzenmike]

 

Check that rotor tip is under the number one plug lead. Firing order is 1342 but in counter clockwise direction. Easy to have 2 and 3 reversed.

 

Choke on? Give a couple of pumps of gas.

 

While someone tries to start the engine YOU turn the distributor clockwise or back see if that gets it firing better. 

[Jayroc]

Tip is under #1, though I posted the picture of the cap showing 1342 with the plugs.  Using a trigger i was turning it over and rotating the distributer with no change. 

 

Electric choke.

[ggzilla]

i dont see the picture

44 minutes ago, Jayroc said:

I posted the picture of the cap showing 1342 with the plugs

[banzai510(hainz)]

to me that distributor shaft off one tooth.  if rotor is on number 1 plug wire but dist is crankd all to one side then dist shaft is off. take dist 10mm bolt off and crank dist over more try again. If runs better then its ofe a tooth. To me you got to move shaft one tooth clockwise

[banzai510(hainz)]

what is that hooky red wire ground to front?making that clean nice engind bay look bad

[banzai510(hainz)]

[Jayroc]

19 hours ago, banzai510(hainz) said:

to me that distributor shaft off one tooth.  if rotor is on number 1 plug wire but dist is crankd all to one side then dist shaft is off. take dist 10mm bolt off and crank dist over more try again. If runs better then its ofe a tooth. To me you got to move shaft one tooth clockwise

Cranked either way no real maybe one way tries to backfire more.  I'll take a better look at the shaft this weekend when I have time again.  But it does look off I agree.

Edited June 5 by Jayroc

[Jayroc]

19 hours ago, banzai510(hainz) said:

what is that hooky red wire ground to front?making that clean nice engind bay look bad

Temp ground wire for the HEI, was trouble shooting and wanted to confirm before I spend time making it look clean.  Trust me it drives me nuts when I look at it as well.

[Jayroc]

21 hours ago, ggzilla said:

i dont see the picture

Should have said i though I posted that picture.

https://flic.kr/p/2r8Ryed

[datzenmike]

11 hours ago, banzai510(hainz) said:

 

 

 

Hard to tell. Looks pretty close.

 

There are ten worm gear teeth and twenty teeth on the spindle. Each tooth would move spindle 18 degrees. Each minute on a clock face is 6 degrees so one tooth out is 3 minutes closer to 11:30 or 3 minutes closer to 11:25.  

[ggzilla]

That is off a tooth. Right now the slot is inline with the two bolts, instead of offset a bit

[ggzilla]

1 hour ago, Jayroc said:

Should have said i though I posted that picture.

 

[banzai510(hainz)]

check for good spark at the center coil wire. and make sure valve lash adjusted.

then fix the spindal

[Jayroc]

Move 1 tooth forward, looks better now.  Going to re check valve lash, and get new plugs as these look a little fouled.

 

 

[banzai510(hainz)]

perfect.

As fore spark plugs I havent bought a set in over 10years on 2 vehicles.

 

but get NGK orNipponDenso

[Jayroc]

Still not firing off, now backfires though the exhaust.  Going to pull the carb and just go though it. It has been sitting a while.

 

Spark is good so it's either fuel or air.  I know I'm getting fuel so my air fuel mixture is happy.

[banzai510(hainz)]

if your sure the rotor is on TDC and on #1 plug wire then goes 1 3 4 2 COUNTER clockwise fire order.

I would shoot starter fluid or pour small amout of gas in carb and start, if should fire off. If not then I say look at distributor Cause pouring gas is bypassing the carb right? so it should fire off or pump the gas so it fills up enough fumes to fire off

Edited June 9 by banzai510(hainz)

[datzenmike]

Backfire out the exhaust is the plug not firing. The unburnt gas is pushed into the exhaust where another firing cylinder sets it off.

 

Clean the plugs or get new NGK BPR6ES. I clean by heating the end with propane torch till it glows. This is the carbon burning off.

 

What condition are the plug wires. Electricity always looks for the easiest path to ground. You have to insure that all components are dry and in good condition so that the easiest path to ground is the spark plug. Check the coil tower also. It may be carbon tracked or crackes and spark will jump to negative terminal.

 

You can just make out the crack to the right of the terminal...

 

 

Check the carburetor and adapter gaskets are sealing. Air leak will lean out the mixture. A very lean mixture burns so slowly that there is still flame in the chamber the next time the intake opens and backfires through the carburetor.

 

 

[Jayroc]

On 6/8/2025 at 8:17 PM, datzenmike said:

Backfire out the exhaust is the plug not firing. The unburnt gas is pushed into the exhaust where another firing cylinder sets it off.

 

Clean the plugs or get new NGK BPR6ES. I clean by heating the end with propane torch till it glows. This is the carbon burning off.

 

What condition are the plug wires. Electricity always looks for the easiest path to ground. You have to insure that all components are dry and in good condition so that the easiest path to ground is the spark plug. Check the coil tower also. It may be carbon tracked or crackes and spark will jump to negative terminal.

 

You can just make out the crack to the right of the terminal...

 

 

Check the carburetor and adapter gaskets are sealing. Air leak will lean out the mixture. A very lean mixture burns so slowly that there is still flame in the chamber the next time the intake opens and backfires through the carburetor.

 

 

Its all new nkg Plugs, wires, and coil , have the old coil as well (swapped both change).  With plugs pulled and near a ground i can get them alittle over ½" and get the spark to jump to ground. 

 

Did pull the carb and reset the float it was well over 18mm.

 

Also removed and re torqued intake manifold 

 

Pulled the new plugs #4 was bone dry and #2 was very very wet with fuel.

 

 

[ggzilla]

what's different? Is one L20B and the other Z24?

 

[datzenmike]

I don't think there is any real difference. The L20B and the Z24 use the same worm gear on the crankshaft, same as the L16 in the 521 and the L24 in the S30.. 15043-21000. If those two pictures don't quite look exact it's just lens aberration and two different people and cameras.