L20B Teardown Help

[Galsia]

                                                                                                                       though admittedly I have lurked about for quite a bit. 

Hello everyone, first time poster here,

 

To preface with the problem at hand, right now I have no compression in my first chamber; the suspected offender is a burnt valve. I plan on tearing down the engine, removing the head, and having it sent to a machine shop for repairs. If someone has a better idea, feel free to advise, to be honest this is uncharted territory for me. 

 

I know a lot of people like pictures, and though I don't have any pictures pertaining to the engine (yet), I gotta put up at least one y'know, so here's an overall shot of my '79 620 King Cab the day I got it in 2016.

 

 

 

As of now I'm not much of car guy when it comes to the inner workings of the engine; with the help of existing ratsun threads I've done things like adjust the idle mix/speed/timing and replace the slave cylinder, but taking the engine itself apart is not something I've experienced yet. 

 

So, my question is, does anybody know of any good visual guides out there for me to get started, and if not possibly snap a few shots themselves and point me in the right direction? Thanks!

[datzenmike]

 

 

At TDC on the compression stroke both #1 cam lobes should be pointing upward at aprox. 2 and 10 o'clock as viewed from the front. Both valves should be fully up and closed. Are they? If one isn't, possibly it's bent. Again it won't close. This is the position to have the cam so the lash can be checked.

 

Have you checked the valve lash? An over tight valve won't close and will cause little or no compression. Clearance should be 0.010" for intake and 0.012" for the exhaust. This is the settings for a hot engine.

 

Oh... really nice 620!!!! ?

[Doctor510]

26 minutes ago, datzenmike said:

 

 

At TDC on the compression stroke both #1 cam lobes should be pointing downwards at aprox. 8 and 4 o'clock as viewed from the front. Both valves should be fully up and closed. Are they? If one isn't, possibly it's bent. Again it won't close. This is the position to have the cam so the lash can be checked.

 

Have you checked the valve lash? An over tight valve won't close and will cause little or no compression. Clearance should be 0.010" for intake and 0.012" for the exhaust. This is the settings for a hot engine.

 

Oh... really nice 620!!!! ?

Please check your post.   The valves on the cam should point UP (10 & 2 / valves closed) for compression.  If they are pointing down the valves will be OPEN.

[datzenmike]

Yes indeed. Been thinking of Z series a lot. Yes lobes most definitely UP on an L series. Thank-you Dr.

 

The front lob at 2 and the intake following at 10.

[Galsia]

4 hours ago, datzenmike said:

 

 

At TDC on the compression stroke both #1 cam lobes should be pointing upward at aprox. 2 and 10 o'clock as viewed from the front. Both valves should be fully up and closed. Are they? If one isn't, possibly it's bent. Again it won't close. This is the position to have the cam so the lash can be checked.

 

Have you checked the valve lash? An over tight valve won't close and will cause little or no compression. Clearance should be 0.010" for intake and 0.012" for the exhaust. This is the settings for a hot engine.

 

Oh... really nice 620!!!! ?

 

I'll certainly check those to ensure they're in proper working order, though I don't think I accurately described my familiarity with engines; I am complete novice, I'm gonna be learning from the ground up here. Am I able to just straight up remove the valve cover right away and begin checking these things, or is there a bit more prep work involved to get to the point in which I can start accurately diagnosing? 

 

[banzai510(hainz)]

Look up my vid on youtube.

Hainz L series timming chain. or soemthing like that