Need Help With Timing Mark Position On New Pulley

[Chiquidrac]

Hello All, 

We are rebuilding an L20B engine to be installed on a 1972 521 truck, this engine came from a 620 truck, here is a picture of the engine before we put it into the truck (with the original L20 crank pulley in it)

 

We got the all the timing marks aligned and it looked like everything was fine, so we installed the engine on the truck.

 

Then we realized that the current pulley ( the one on the picture with three grooves) was to close to the frame, so close that it was almost impossible to put the new belt on, so we decided to replace that pulley with another one we had from an L18 engine (single groove).  The problem is that when we aligned the engine to be top dead center on compression the new pulley will be on the 1 oclock instead of the 11 oclock the previous pulley mark was, therefore far away from the timing marker that was align with the original pulley. 

 

Here is a picture that shows with arrows what I am talking about. 

 

I did some research and couldn't find enough information to figure this out so I am hoping someone will know what is going on.

 

Thank you in advance. 

 

 

 

 

 

[G-Duax]

Use the pointer from the L18, it mounts on the other side of the front cover, under the distributor.

 

This is a custom pointer, but in the stock-ish left side position:

 

[Lockleaf]

You can use a piston stop tool to determine actual top dead center and then make new marks on your pulley that align with your current timing tab.

 

Chevy guys do this often.

[flatcat19]

What G-Daux said. L Pulleys have matching pointers.

 

And since the covers are all basically the same the pointers will fit all even though they all mount different.

[flatcat19]

In your engine picture, you don't have hose clamps on the bypass hose.

 

Leaky-leaky.

[Jester]

 

 

I did some research and couldn't find enough information to figure this out so I am hoping someone will know what is going on.

 

Thank you in advance. 

 

What they said. Good looking engine by the way. 

1 thing I find interesting is that they appear 90* off. Wonder if you could just time it from #4 cylinder?

 

In your engine picture, you don't have hose clamps on the bypass hose.

 

Leaky-leaky.

 

I noticed that too. 

 

Use the pointer from the L18, it mounts on the other side of the front cover, under the distributor.

 

This is a custom pointer, but in the stock-ish left side position:

 

 

Oh, do tell more. Please.

 

Edit:  I found it.

[Doctor510]

There is a proper timing plate for the driver's side of the motor

[datzenmike]

That EGR block off plate needs to be drilled and tapped for the PCV valve. It's a big no no to run without the PCV.

[Chiquidrac]

Ok,  Thank you for all the advice.  I was concern that something was wrong with the timing.  I will try to find the marker from an L18 to make it right and if I can't I will put a new mark on the pulley after finding top dead center.

 

Also, I did get the PCV valve into the EGR block off plate and got all the hose clamps in place (thanks for noticing)

 

I'll update pictures later today, I am anxious to run it since it is my first rebuilt engine.

 

Thank you again guys.

[banzai510(hainz)]

If you rebuilt the motot then you know where TDC is !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

then use that mark.

 

If you changed the pulley and it used a different mark or system you should have noted this .

 

Find the correct pully as I have a L18 and a L20 and they use a sawtooth timming plate but one motor its on the left side the other is on the right , so if show 2 differt type of pullys then the L16 with the pointer is another, 3rd

 

olddatsuns.com has more than enought infor to get by.

 

to wing it I would get the piston close to TDC . One can open the oil cap and see the lobe position. 10ex and 2in oclock then look in sparkplug hole and turn pulley till loks TDC and mark the front cover and pully with a mark and call that close to Zero.

[Stoffregen Motorsports]

Reinstall the L20B large crank pulley and pointer. Make sure the crank bolt is loose.

Bring the engine up to TDC using the L20B crank pulley and pointer.

Remove the pulley (without turning the engine).

Tap new pulley onto crank.

Make new timing mark on crank pulley to correspond with L20B pointer.

Done!

[TDCTDI]

What they said. Good looking engine by the way. 

1 thing I find interesting is that they appear 90* off. Wonder if you could just time it from #4 cylinder?

 

 

 

 

Edit:  I found it.

90* at the crank isn't #4, piston TDC on #1 & # 4 are the same, 180 from there would be piston TDC on #s 2&3. 90* would be half mast of all four pistons.

[Chiquidrac]

Looks like I am done,

 

PCV valve done

 

L18 timing marker done

 

Clamps done

 

 

Thanks for all the advice, by the way this site was my mine source of resources to be able to complete this job, I don't think I could have done it without the tons of information this site provides.

 

Thank you again

[Chiquidrac]

Wrong pic on the marker

 

 

Greetings

[G-Duax]

Good Job !

 

Now come over and help me finish mine.

Wait, you are 800 miles away, dang !  :(

[TDCTDI]

Nice. Just looking at the pic of the carb, you can clean up the fuel line routing by moving the fuel inlet barb from the 4 o'clock position to the one at the 8 o'clock position & replace it with that plug.

[Lockleaf]