Hello! New 77' 620 owner

[FLUX]

Hello all, it's nice to be apart of another Datsun forum. I was wondering if you guys could answer some questions I have about headgasket replacement.

 

Well here it goes, the other week I bought a 1977 Datsun standard cab in Mesa Arizona. It's been there its whole life and has almost no rust, which is the only reason I bought it! Mainly because mechanical work I can do, body work I can't do for crap (yet). The previous owner said that he replaced the headgasket and then the truck was fine for two months and then it blew the second headgasket. The previous owner says that he did not have the head resurfaced when he did the headgasket and he didn't torque the head to the correct specs. So, I'm in the middle of tearing this thing apart to get to the headgasket. Here are my questions...

 

When I have the head pressure tested and resurfaced, I read that if it's resurfaced to much I will need to use shims. Where do these shims go?

 

When I do the head gasket should I replace the tensioner and timing chain guides? If so which brands are the best?

 

And lastly, when I took my water pump off I found that the inside of the water pump housing (timing chain cover) was corroded. It doesn't look to bad, but I want to replace it if I can to prevent any future overheating.

 

Thanks again!

[datzenmike]

The shims go under the cam towers to move the cam higher the same amount of material removed from the head. This will keep the timing chain properly tensioned and eliminate slack being added. Myself? 0.010" shaved off isn't worth worrying about. There is a chain tensioner that takes care of this anyway. 

 

As long as it's made in Japan you can't go wrong with chain.tensioner and guides.

 

Corrosion is from not running antifreeze coolant. People think it's for the cold but it prevents corrosion. Always use distilled water that is mineral free. You may want to look inside the rad cap and see if the tops of the rad tubes are also crusty. If replacing it you want one from an L20B motor car or truck are the same.

 

L20Bs has a pair of bolts on both sides at the top. Earlier L16 and L18s have only one bolt.

[FLUX]

Okay thanks! I just got some Felpro gaskets and hope to have the head off soon to take to the machine shop to have checked for warpage and pressure tested. Do the tensioners run off oil pressure or just the huge springe inside? Also, I have heard of a wedge tool being used to somehow depress the tensioner? Does anybody have a picture or could explain how this is used?

[K_trip]

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[FLUX]

I totally understand that! I'll do a search and see what I can find. I just took the lazy route ;) I'll see if I can get some pictures up later tonight!

 

Btw: I've been to Santa Cruz, wonderful place! Loved the big dipper roller coaster!

[K_trip]

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[Z-train]

You don't need no stinking shims!Shims change the rocker/cam geometery.Measure the height of the head and get back to us.More than likely,all you need to do is advance the cam gear to the #2 hole.

[Farmer]

Welcome to Ratsun

[FLUX]

Okay so yesterday I got the head off. The tops of pistons 2 and 3 are washed clean while pistons 1 and 4 have carbon. Also the gasket was black and burned inbetween cylinders 2 and 3. Going to have the head dropped off at the machine shop for pressure testing and warpage check. Also, due to the coolant being in cylinders 2 and 3 it looks as though my cylinders have been glazed. I'd like to replace the rings and hone the cylinders. Any brand of pistons rings you guys recommend? Thanks, FLUX