Datsun L20b timing

[Shemmy]

Good morning!

 

I know there have been lots of similar questions, however I couldn’t find mine on this site.

I have an L20b engine, and I’m replacing the head gasket. I have the head off my block and I’m just cleaning it up a bit and then I want to put it back on the block, I also have the whole front cover of my engine off so it’s easy to set crank timing etc. 
 

my question, the head is supposed to be in second position on the dowel for timing and  the in and ex at 11 & 14. Initially when I set it I thought it was correct the in and ex were correct but on closer inspection I found it was number 1 dowel, however the valves were closed. I turned it to the middle (#2) and one valve is partially open and the in and ex are not at 11 and 14. 
 

should I just set for #1? 
and have the in and ex closed as a result? I do want the those valves closed at TDC right? 

[datzenmike]

 

 

Sorry for the long wait Canuk, and welcome to Ratsun.

 

 

The engine must be at Top Dead Center. No way to check really but if the #1 and #4 pistons are at the top of the cylinders, good enough for now.

 

If at TDC, and head is off, turn the cam till the first cam lobe (exhaust) is at about 2 o'clock and the second one back (intake) is at 10. You can now safely lower the head onto the block aligning dowels with a new head gasket. Dry with no sealers and both surfaces clean enough to eat off of.. You can put the head bolts in but don't tighten them just yet. When you put the timing cover back on it's handy to lift the front of the head to slip it in.

 

The timing chain should have two dots punched into it exactly 44 links apart. The crank sprocket has a matching dot at about 4-5 o'clock. The top dot should match the cam sprocket on the #2 setting. You can lift the cam sprocket up onto the cam and lightly install the cam retaining bolt and fuel pump eccentric finger tight. There should be enough chain slack to slip the chain tensioner into place now.

 

 

Install the timing cover. Torque head bolts in this sequence...

 

R..A..D

7.......8

3......4

1.......2

5......6

9....10  to 20 ft lbs, then same sequence to 40 ft lbs. and then same sequence to 60 ft. lb. Today's gaskets do not require re-torquing. Don't gorget the two 10mm bolts through the front of the head into the timing cover.

[Streetfilthoriginals]

On 7/30/2021 at 11:20 AM, datzenmike said:

 

 

Sorry for the long wait Canuk, and welcome to Ratsun.

 

 

The engine must be at Top Dead Center. No way to check really but if the #1 and #4 pistons are at the top of the cylinders, good enough for now.

 

If at TDC, and head is off, turn the cam till the first cam lobe (exhaust) is at about 2 o'clock and the second one back (intake) is at 10. You can now safely lower the head onto the block aligning dowels with a new head gasket. Dry with no sealers and both surfaces clean enough to eat off of.. You can put the head bolts in but don't tighten them just yet. When you put the timing cover back on it's handy to lift the front of the head to slip it in.

 

The timing chain should have two dots punched into it exactly 44 links apart. The crank sprocket has a matching dot at about 4-5 o'clock. The top dot should match the cam sprocket on the #2 setting. You can lift the cam sprocket up onto the cam and lightly install the cam retaining bolt and fuel pump eccentric finger tight. There should be enough chain slack to slip the chain tensioner into place now.

 

 

Install the timing cover. Torque head bolts in this sequence...

 

R..A..D

7.......8

3......4

1.......2

5......6

9....10  to 20 ft lbs, then same sequence to 40 ft lbs. and then same sequence to 60 ft. lb. Today's gaskets do not require re-torquing. Don't gorget the two 10mm bolts through the front of the head into the timing cover.

Got a question for about the cam towers. How to prevent camshaft/tower?

[datzenmike]

How to prevent camshaft tower.....what?

[Streetfilthoriginals]

On 7/30/2021 at 11:20 AM, datzenmike said:

 

 

Sorry for the long wait Canuk, and welcome to Ratsun.

 

 

The engine must be at Top Dead Center. No way to check really but if the #1 and #4 pistons are at the top of the cylinders, good enough for now.

 

If at TDC, and head is off, turn the cam till the first cam lobe (exhaust) is at about 2 o'clock and the second one back (intake) is at 10. You can now safely lower the head onto the block aligning dowels with a new head gasket. Dry with no sealers and both surfaces clean enough to eat off of.. You can put the head bolts in but don't tighten them just yet. When you put the timing cover back on it's handy to lift the front of the head to slip it in.

 

The timing chain should have two dots punched into it exactly 44 links apart. The crank sprocket has a matching dot at about 4-5 o'clock. The top dot should match the cam sprocket on the #2 setting. You can lift the cam sprocket up onto the cam and lightly install the cam retaining bolt and fuel pump eccentric finger tight. There should be enough chain slack to slip the chain tensioner into place now.

 

 

Install the timing cover. Torque head bolts in this sequence...

 

R..A..D

7.......8

3......4

1.......2

5......6

9....10  to 20 ft lbs, then same sequence to 40 ft lbs. and then same sequence to 60 ft. lb. Today's gaskets do not require re-torquing. Don't gorget the two 10mm bolts through the front of the head into the timing cover.

Got a question for about the cam towers. How to prevent camshaft/tower from binding. My apologies. 

[datzenmike]

 More info.

 

The cam should easily spin by hand with all the rockers off.

 

Is the cam in and tight to turn? can't get it out?

Is the cam out and won't go in?

 

Have the cam towers been removed? Could they be back in the wrong order? Front one is unique but the last 3 look the same. Do NOT over tighten the bolts. They will strip.

 

Unlikely but could the cam be bent? 0.0008" is normal and 0.002" absolute limit.

 

Even more unlikely is the head bent?

[Stoffregen Motorsports]

The cam towers may need to be knocked around a bit with a rubber mallet to get them square again. Assuming they were put back in the same order. The cam should spin freely by hand, but a bit of drag is acceptable.