Getting out of Cali (timing, spark plugs, etc)

[Radiant-Designer]

I have a 77 620 that I picked up in Cali. It now lives in New Hampshire where its much colder and has some brutal winters. Some of what I had done was remove all the smog stuff when I went to my Weber carb. I am wondering should I readjust the timing and so on to the non-cali specs since a lot of that stuff is gone?
 
Also I may want to just replace the timing chain and components for piece of mind (not sure its ever been changed) whats a good kit to get? 
 
L20b, 1975-1977

Non-California 12º BTDC

California 10º BTDC

1977 Cai, all 1978:
Standard type: NGK BP5ES-11
Hot type: NGK BP4E-11, or BP5ES-11
Cold type: NGK BP7ES-11

 

1977 non Cali:
Standard type: NGK BP6ES
Hot type: NGK BP4E, or BP5ES
Cold type: NGK BP7ES

[datsunaholic]

One of the reasons the specs are different from Cal to non-cal is California trucks in 1977 had electronic ignition.  Non-cal had points.  So unless you've changed to points too, leave the spark plugs alone.  Or, go to BPR6ES-11 plugs if you want a colder plug.  The -11 is because the EI used a wider plug gap; the -11 plugs have a longer electrode to account for that.  Spark TIMING OTOH is based on HC/NOx emissions standards so you can set that to 12, unless it starts pinging.

[datzenmike]

There is no need to replace the timing chain unless... damaged or stretched.

 

To check for stretch find TDC on the compression stroke number one cylinder. You can simply line up the notch on the crank pulley with the 0 (zero) on the timing scale below the water pump and above the alternator.  Be sure to turn the motor up to and stop at the TDC mark while going a clockwise direction. It very easy to overshoot so if you do, back it up well before TDC and try again as many times as needed to get this right. Backing up (counterclockwise) to TDC will introduce slack to the tension side of the chain and make an accurate measurement of slack a waste of time. Once you have an accurate TDC....

 

Remove the valve cover and with a flashlight look through the top hole in the cam sprocket. The back of the sprocket should have a Vee or U notch in it that is positioned just below or slightly to the right of the small horizontal line etched into the cam thrust plate behind it. It should look like this...

 

 

If yours is like this it's fine. If the notch is slightly to the left there is even a way to adjust it.

[Radiant-Designer]

Thanks for the info, next time I get a few hours on a weekend i will check the timing more. I figure I can do that at the same time I adjust valve clearances too (something that I have been meaning to do for a year now).

 

i didnt get the -11 plugs last time I ordered fro, the parts store, I may just order a set from Amazon. The difference cant be made up when you set the spark plug gap?

 

While I am asking whats the difference between a cold plug and a hot plug? is it ambient temps or what it runs at??? or what?

[datsunaholic]

Spark Plug heat range has to do with the firing temperature of the plug itself.  More powerful engines usually need colder plugs.  The general range of firing temperatures can be anywhere from 900 to 1500 degrees, which is a 600 degree range, FAR in excess of what the outside temperature range is.  Ambient temperature has nothing to do with plug heat ranges.  It's all about driving behavior, horsepower, fuel mix, cylinder pressure, etc.  If you're burning up plugs, go colder.  If you're fouling them (carbon fouling), go hotter.

 

The -11 just means that the plug is optimal for a 1.1mm gap.  You can use standard plugs and widen the gap, the plugs simply aren't optimized for that wide of a gap from the factory, so the electrode may no longer be perfectly centered.  Plug Manufacturers did that when EI came around because the OEM plug gaps changed by a significant amount.

[Radiant-Designer]

good to know. When i first got the truck it had the BP6ES in it and I put the 5ES-11 in it when I changed the cap and rotor as part of my traditional new to me car once over. it seemed to have ran better with the 6ES in it (it could have been the 6ES-11, I didnt pay much attention at the time) 

 

So looks like I will put the 6ES-11 in and see how that runs. maybe I will change the cap and rotor too, cheap enough. Its been about 2 years.

 

A while back I had a Vacuum leak on the Weber (ended up being the base plate became a little loose) well at the time I couldnt find it and ended up over compensating by running it rich. I since fixed it but I think it took a toll on the plugs anyway.