L20B Heads

[Humboldt]

Can I mcGuyver out the steel sleeves in the exhaust manifold (currently off 1980 720 L20B W58) without taking the head off to open it up? Rip them out with brute force/vice grips?  Just askin'!

 

[datzenmike]

No. They wrap around the valves. With the valves out I have split them lengthwise with a chisel in a couple of places and twisted them out. First one took 45 min, the last about 15 min. Not really any gain, but it feels good.

[kgrantkey]

 

 U67 would be my second choice with a port match to the intake. Stock compression. If your intake has coolant in the runners you would have to drill two small holes in the head.

 

Could you elaborate on this ?

 

Are you saying to run a U67 head with a manifold that has coolant flowing thru it here is a modification that should be done, and what is it?

 

I have a reason for asking.  The U67 head I assumed to be flat on the bottom is leaking coolant between the head and block with never even being started. Just filled it with about 50/50 antifreeze and decided to call it a night. Was gonna crank her up and test drive it the next day.

 

I saw a puddle under my engine and traced it to droplets squeezing out the spark plug side between the head and block for about two inches starting just behind the Nissan U67 stamp, about midway of the head. So it's not on the intake side. And I'm pretty sure my intake has a couple of hoses that feed water thru it.

 

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I feel it's obvious I have a warped head and have cussed myself for not just using the w58 I had the shop rework a few years but very few miles ago,

 

Such is life. 

 

I have ordered a   Nissan Timing Chain Holding Tool                                                                                                                      

 

 

in preparation to pull the head.

 

 

 

  My plan is to reassemble the W58 while waiting on the tool to arrive.  Let the Head shop go over the U67  and change it at a later date.  It's got to be warped to leak coolant like it is, even if I didn't torque it quite enough, and I'm confident I did.

 

Just so damn disappointed as I came so close to just putting the U67 aside and going with the known good W58.  I'll never race this truck and a few horsepower is not worth what I've done to myself.

 

Well I may finally figure how to mount the toyota alternator with the built in rectifier so I can quit worrying about that, I've picked up enough mounts over the years and have either side of the motor to try and make it fit.

 

I just dont want to drop my chain and go thru what happens then.    Man am I bummed out.

[ggzilla]

Defective gasket. When you get the head off check it on a straightedge. If you can fit s 0.004 feeler then its not warped. Have had new gaskets leak when the head was fine., it was the new gasket.

[kgrantkey]

Defective gasket. When you get the head off check it on a straightedge. If you can fit s 0.004 feeler then its not warped. Have had new gaskets leak when the head was fine., it was the new gasket.

 

This was the 1st time I put no rtv on the headbolts that enter the water jackets. I've always done that before. It may have been a contributing factor. I'll know one day in the future when I revisit the U67 head.  I don't remember ever using a head that had not at least been looked over by a good machine shop.

 

On the other hand I don't ever remember a shop telling me this head doesn't at least need a resurface.  I'vr always wanted a weber carburetor for my truck. If or when that day arrives I'll have the U67 ready to pair with the weber and probably be time to check the exhaust.  Combined those changes done properly could have a good influence on the power band if nothing else.

 

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I have an old stereo stand with a big glass door I've been hanging on to with the thought I could put together something that would make for a nice way to check such things for flatness. I have a large piece of clear lexam that could go under the glass for strength. All I need is time and another flat table or area to put it.

[datzenmike]

NONE of the headbolts go into the water jacket. RTV on the bolts? never. This is not what it's for and unless fully removed may affect the tightening of the bolts when they go back on. RTV will just may a job even messier. Bolt and block threads MUST be clean.

 

 

Better to check the head for flatness yourself. It's not rocket science and will save you an unnecessary bill from a shop that will check it and then tell you it needs to be milled anyway just for the work. 

 

 

 

The head gasket goes on dry and is torqued from the center outwards, like this...

 

R A D

7....8

3....4

1....2

5....6

9..10

 

Tighten all bolts in this sequence to 20, then again to 40 and last to a final 60 pounds. Wipe the bolt threads with an oil rag and place a drop of oil on the washer under the bolt head.

[ggzilla]

Yes, only bolts that go through a water jacket need sealer. Not Datsun head bolts.

 

 

> On the other hand I don't ever remember a shop telling me this head doesn't at least need a resurface. Of course a burnt channel is a reason to mill the head.

 

Yes shops are trained to say that. It is a big revenue generator. You can trust Nissan though.they say head skimming is not part of a rebuild unless the head is more than 0.0039 out of flat.

 

You can use a edge such as a *quality* level. Check for flatness of the edge by lining up two of them together. The precision of a certified straightedge is not required.