Just bought a 521

[mainer311]

Good to know, thanks. I do have an aftermarket aluminum rad with the 90 at the bottom.

[mainer311]

Head is off. Wedge worked great.

 

Definitely glad I pulled the head. It looks like coolant may have been leaking into cylinder #4. It also looks like the original gasket. 
 

I’m debating with myself on whether I should rebuild the entire head, or just clean it up and slap it back on.

 

Also, if the head is the original thickness, how much can it be decked before I have to shim the cam? 
 

Edited January 5, 2020 by mainer311

[mrbigtanker]

At least get the head re decked so it's flush and do the exhaust and intake also. You are right there .

[Crashtd420]

The one thing I would check is your valve seats.... make sure none of them are sucked up into the head or the valves have any play.... now would be the time to correct that...

You could also flip the head over and fill the combustion chamber with something to make sure that are sealing... if all that is good I would skip the rebuild.... 

You could probably just do the flat surface and sandpaper trick....

If you never over heated the engine it should still be flat....

 

[datzenmike]

Take rockers off. Easier to measure and keeps valves out of the way and aluminum dust out of the ports.

 

With a straight edge on a clean head measure diagonally along the length in an X if you can get a 0.004" feeler gauge under it... it should be re-surfaced. Check specially between 2 and 3.

 

Get a glass stereo cabinet door and spray glue some 80 grit paper to it. Set on a table and letting the head's own weight provide the down force, use the sprocket end and pull forward and push back. After about 20 check the head. If there are any high spots they will be apparent next to the obviously clean sanded areas.

 

Obviously a little high in the middle after 20 passes. Every 20 lift off and blow the dust off or it will act like ball bearings.

 

40 more passes. As it progresses there is more contact with the sand paper and more to remove so it takes more passes.

 

 

60-80 more passes and only between 2 and 3 is left.

 

 

 

 

Head was NOT warped as the cam easily turned by hand in it's towers. The middle of the head was high or puckered, probably from severe over heating and why this head was given to me. It would allow a  0.015" feeler to pass, almost 4 times the allowable limit!!!

 

Your head will not be anywhere near this bad and this will simply clean it up and is better that gouging it with a paint scraper.

 

The shrouding around the valves was severely cut back as this was going on a Z24 block.

[d.p]

Just take it to the machine shop and have it cleaned up, decked and new valve seats done. Might as well as you’ve already got it off. 

[banzai510(hainz)]

Getting back to the Gates hoses they are all fine the Lower and Upper. The Upper might be too long if installed on a L16/18 as it might put a bind in the S shape of the hose as it will go on but is slightly too long/ Maybe this is case the L20 is 3/4 inch higher in the later vehicles. But that's what I noticed  or it Vise Versa L18 to L20.

 

 

If Me I would just bolt the head back on and find another head to mod and take your time and set up and bolt that on later or for a bigger motor(L20)

[mainer311]

Going to use Mike’s method using sandpaper, but probably a finer grit. We have a granite inspection plate at work that’ll work awesome.

 

Also just bought new valve stem seals, a compressor tool, and valve lapper/compound. Will disassemble and check the seats, clean the valves, and do a quick lap to remove any deposits. 
 

At least I have all winter. 

[wayno]

If your going to rebuild the head make sure you have them put hardened seats in it.

When the valves sink into the head I do not believe the seat moves, the seat just disappears and the valve sinks deeper into the seat, this is caused by the fuel they sell and how deep ones foot is into the pedal, I carried weight and hailed a trailer around, I also took a trip from Washington State to Florida State fully loaded about the time I put the new super head on the engine, by the time I got back from that trip(about 8000 miles total) the dogleg transmission was toast, and I had ran out of valve adjustment on one of the valves.

You can tell if you have valves sinking into the head by looking at the valve end tops from the side, if some of the valve tops/spring keepers are higher than the others you have issues(especially noticeable when the rockers are removed), hardened seats are a must unless your top speed is 55mph, my machinist said if I could keep my foot out if it I would not have an issue, I replied I haul a lot of weight and tow a trailer, install hardened seats.

Another thing I would say is do not rebuild or waste a lot of time on a 210 head, find a better head, better yet find an L20b and a better head and rebuild that, it was the best upgrade I have ever made going from an L16 to an L20b, second best upgrade was either going from an L20b to a LZ23 or going from a down draft carb to dual SUs, I will also say that I don't know where my super head fits in here, when I put the L20b/dogleg 5spd into my 521, I also built a W53 head and installed it, the intakes were port matched to the SU manifold, and I had 280Z valves put into the head, I took my trip about 6 months later and I lost the transmission and seats on that trip, but I did make it home, that transmission was howling, and one of the valves had no more adjustment, I cut the adjustment lock nut in half, but soon other vales were out of adjustment also.

[mainer311]

I’ll check them when I get it apart. I only really drive the truck on nice days 3 seasons out of the year, and only on backroads to work/car shows. I understand it’s not a race car, but I’d like it to see some spirited driving every once in a while.

[wayno]

Every day I drive is a workout for my truck/trailer, the combo weigh over 6000lbs(3 tons), sometimes over 8000lbs when the truck is fully loaded with wet moss, but I had hardbody dual piston disc brakes and electric trailer brakes, I don't work so much or hard anymore.

Edited January 6, 2020 by wayno

[datzenmike]

 

Notice the intakes are a coppery color? I think they are bronze. The old fuel with tetra ethyl lead (an anti knock ingredient) also lubricated them preventing wear. Newer gas doesn't use lead and the old seats wear out. The valve rises upwards into the head and the clearance becomes tighter and tighter till they are loosened by adjusting the pivot post downwards. At some point you can't loosen them any further the pivot bottoms out and the head becomes useless. Valves don't wear based on how much load you carry they just open and close.

 

Threaded pivot ball on top with adjuster nut below it

 

Just for an experiment I ground down the thickness of the adjustment nut so the pivot ball could go lower. It worked and gave me another 0.020" of room. Something to keep in mind if one or your valves runs out of adjustment room. It isn't a cure but it could see you through a road trip or through the winter and fix properly in the spring.

 

Two adjustment nuts. Stock one on the bottom.

[Stoffregen Motorsports]

Good wrenches (Snap-On) make adjusting valves easier. Cheap wrenches flex and will eventually damage the adjuster nut. Snap-On used to make (don't know if they still do) a crows foot type wrench for the large jamb nut, and though they aren't great while actually adjusting the valves, they are great for breaking them loose.

 

Here's one on ebay - https://www.ebay.com/p/1926243914?iid=264541346032&chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=264541346032&targetid=541454149372&device=c&mktype=pla&googleloc=9032531&poi=&campaignid=6470552634&mkgroupid=81274458647&rlsatarget=pla-541454149372&abcId=1139336&merchantid=6296724&gclid=EAIaIQobChMIwPatmqnv5gIVyrzACh1VbQFVEAQYCSABEgI2yvD_BwE

[greenthumb]

A question to Mike about the glass method of resurfacing. Glass does have a certain amount of flex to it. You don't worry about that a little? Mainer's granite inspection plate sounds like just the ticket. 

[mainer311]

Inspection plate worked awesome this morning. I started with 220 grit and the head is almost perfectly flat. I finished it with 400 grit and will probably call it good. Spring compressor tool should be by Saturday, so I’ll wait and see what the seats look like. In the meantime I’m going to start the port matching.

[mainer311]

Some goodies arrived. I’m not super impressed with the head gasket. It has sealant around the passages, but only on one side. Not really sure why.

 

[datzenmike]

5 hours ago, greenthumb said:

A question to Mike about the glass method of resurfacing. Glass does have a certain amount of flex to it. You don't worry about that a little? Mainer's granite inspection plate sounds like just the ticket. 

 

The glass was 1/4" thicker is always better, and well supported underneath on a table top. I tried 180 grit early on but too fine. I think it was 80 that I used, then when done, a few passes on the 180. The end result was a surface that I could not get a 0.002" feeler under. I was using a SS industrial straight edge for the measuring. Every 20 passes I would turn the head 180 and push pull the other way.

[datzenmike]

2 hours ago, mainer311 said:

Some goodies arrived. I’m not super impressed with the head gasket. It has sealant around the passages, but only on one side. Not really sure why.

 

 

The underside.

[banzai510(hainz)]

I think the Felpro is like that also only on one side(cant remember)

 

my(durapro) Graphite Japanese ones don't have sealant. I don't believe the Nissans do either

 

that Sanwa gasket look almost like a Felpro(composition type material)

[mainer311]

8 minutes ago, banzai510(hainz) said:

that Sanwa gasket look almost like a Felpro(composition type material)

 

It has the metal rings around the cylinders and oil galley, and then the whole thing is painted this dark gray color prior to the addition of the sealant.

[d.p]

A lot of talk about gasket type, thickness, coating when a Fel-pro works just fine.   

[datzenmike]

I have no problem with them. Prep.... is everything.

[mainer311]

10 minutes ago, d.p said:

A lot of talk about gasket type, thickness, coating when a Fel-pro works just fine.   

 

I'm just trying to avoid the leaking situation I had before. It would be one thing if the engine was out, but I'm doing this insitu, so I have limited access to the block. Cleaning the mating surface as best that I can. 

[d.p]

52 minutes ago, mainer311 said:

 

I'm just trying to avoid the leaking situation I had before. It would be one thing if the engine was out, but I'm doing this insitu, so I have limited access to the block. Cleaning the mating surface as best that I can. 

 

I did the exact same thing, bottom end left in the truck and the head was off and machined.  Put it all back together and no leaks but I did have a loose tensioner.  Lol but no leaks!!!

[banzai510(hainz)]

Mainer I think since you sanded the head youll be fine as for the leak by number 4 cyl.

Felpro Headgaskets are OK on L16s(83mm) for sure but on L18 and 20s the gasket bore is almost hanging in the bore(85mm) what I seen.  . If if one bores a 85mm too much I would find a Nissan Compitition gasket like a 87mm if still avail. or can find one. I heard Nissan ran out of those years ago unless somebody has one on Ebay. I THINK I SEEN 88MM VERSION OUT THERE ALSO