Resurfaced head on L20b. Need a shim?

[justin720]

Hi all,

 

I'm new to the forum, pretty new to Datsuns, and new to doing my own mechanical work. I've been lurking here for a while and getting tons of good info. I've watched the L16 timing video by Hainz (awesome) and learned a bunch from you already.

 

Here's my situation. I blew a head gasket and have been working on replacing it. I just got the head back from the machine shop and not sure about shimming or not. Here are the specs:

 

Original height: 4.251

Shop removed: .007

Current height: 4.244

 

New head (via machine shop): 4.26

Minimum height: 4.245

 

So by my calcs I'm .001 to short. If I add a shim (http://www.rockauto.com/catalog/x,carcode,1210206,parttype,5420,a,www.google.com%2BSearch%2Bfor%2BFEL-PRO%2B21178SP) then it bumps the overall height to 4.266, .006 too high.

 

So I'm at a bit of a loss. I have the timing chain resting on the wooden block to keep the tension so I can't reset the timing. Should I have the machine shop resurface it again so that by adding the shim it equals the exact height it was before?

 

I saw these recommended in another thread: http://www.silver-seal.com/product/HSDT1000/Head-Saver-Shim-Kit-For-Datsun-4-Cyl.html

Those would get me to 4.244 + .015 = 4.259. But I'd prefer not to mess with the cam towers if possible.

 

Here are a couple of pics:

 

Any advice?

 

much appreciated,

Justin

[banzai510(hainz)]

dont worry about it. Just put the head gasket on.

 

Ok if your using the timming chain tool. when you go to put the sprocket back on. make sure the head is at TDC . Your going to have to pick if you want #1 2 or 3.L20s came from factory at #2. So I say put on #2.

 

now when you put the sproket back on hopefully you marked the chain where the dimple or brite link would be. If head was removed you just use a marker or Pen or soemthing. Cause to get the marks to line up again will be a pain. Mostly used for intial set up when brite links used.

 

So anyway put sprocket on It might be hard to get it on the cam dowl so you might have to move the cam in dierection to add slight slack on the tension side of chain. I use a big adjustable wrench on those cam bosses in the center of cam and wack it a cunt hair left or right in dierection you need and then sprocket will go on.

[justin720]

dont worry about it. Just put the head gasket on.

 

Oh man you just made my day! So just to understand. Why is it ok to just put it on?

 

Ok if your using the timming chain tool. when you go to put the sprocket back on. make sure the head is at TDC . Your going to have to pick if you want #1 2 or 3.L20s came from factory at #2. So I say put on #2.

 

OK, so I thought that when I marked the sprocket and chain I thought that automatically lined up the chain, sprocket, and cam. But the cam needs to be lined up in a certain way?

 

now when you put the sproket back on hopefully you marked the chain where the dimple or brite link would be. If head was removed you just use a marker or Pen or soemthing. Cause to get the marks to line up again will be a pain. Mostly used for intial set up when brite links used.

 

Please forgive the lack of knowledge. I did mark the timing chain and sprocket. See pic below. And the #1 piston is at TDC in compression. Did I need to do something more than that?

 

So anyway put sprocket on It might be hard to get it on the cam dowl so you might have to move the cam in dierection to add slight slack on the tension side of chain. I use a big adjustable wrench on those cam bosses in the center of cam and wack it a cunt hair left or right in dierection you need and then sprocket will go on.

 

Ok, I'll see how it works out. I figure if I was able to get those obnoxious manifold bolts off, then I should be able to do this.

 

Here's a few more pics. Sorry for the low res:

 

 

 

 

[banzai510(hainz)]

Ok I cant see all the photos for some reason. sorry I only see the distributor cap one.

 

if milled over .015 then I myelf would get a shim. Otherwise dont worry about it. I have .010 shaved off before and its no bigg deal.

Put it ON?? well if head straight and you got a new head gasket I guess thats all that is needed.

 

As when I say put the cam/head to TDC .I say that incase the machine shop moved things around. Most time they will take the cam off/out if otherstuff is needed. I can only assume . Unless you tell me what they did I have to assume the worst case. But its EZ. Look to see if the lobes are in the correct position and the dimple mark in the right location. In dought pull the sprocket off and the dowel should be in the 12oclock positon. Put sprocket on #2. The dash and the V on the sprocket you just line them up.

Hopefully its already done as Its going to be a MF to turn that cam sprocket as you cant mount it back on the motor intill you have it at TDC. Got to clamp it down.

 

OK. you got the head on and its preety close to perfect. Now put the sprocket on the chain(since you have it marked already its even EZer) and now you got to pull up and get it on the dowel. Now it maybe be close but you just cant get it. You need to move the cam one way or the other. usually need to turn the cam to the right so you can get a slight more slack on the tite side of the chain. I have a big adjustable wrench on the cam boss and just bump it over.

 

 

the distributor photo? if that where #1 plug wire is at then that where its at.

I usually leave the plug wires attaeched to the dist cap and pull the cap off. If the oil pump was not dropped or front cover removed you dont do anything just put the dist cap back on.

 

 

sounds like you have this figured out

[datsunaholic]

If you marked the chain and sprocket before removing, and it's in the same spot now should be OK. I did this last year (ish) but I had to change dowel holes... it had been on the wrong spot anyway (#1) and I moved it to #2 and it runs MUCH better than it did before. I never measured how much they took off the head, though- they basically just skimmed it. I've seen heads with almost a quarter inch taken off (machined halfway through the casting numbers), that's WAY too much.

[justin720]

As when I say put the cam/head to TDC .I say that incase the machine shop moved things around. Most time they will take the cam off/out if otherstuff is needed. I can only assume . Unless you tell me what they did I have to assume the worst case.

 

Yes they did rotate the cam but they didn't take it out. From the picture above (can you see them now?) the dowel is in the 12:00 position. Does that mean it's TDC? Can I just use a large channel lock to turn the cam if I need to?

 

I was watching your video again. Where you were talking about putting the bright link on either the #1 or #2 or #3, I don't think I can determine by the bright link because I did not remove the chain from the lower sprocket. So I'm assuming that my chain is where it is, can't be changed, but I can only turn the cam and sprocket.

 

If you marked the chain and sprocket before removing, and it's in the same spot now should be OK. I did this last year (ish) but I had to change dowel holes... it had been on the wrong spot anyway (#1) and I moved it to #2 and it runs MUCH better than it did before. I never measured how much they took off the head, though- they basically just skimmed it. I've seen heads with almost a quarter inch taken off (machined halfway through the casting numbers), that's WAY too much.

 

When you say you moved the dowel do you mean you just rotated the cam until the dowel was where you wanted it? I'm not sure if mine was ever set right also so if there is a chance mine could be improved that would be great.

[banzai510(hainz)]

Yes they did rotate the cam but they didn't take it out. From the picture above (can you see them now?) the dowel is in the 12:00 position. Does that mean it's TDC? Can I just use a large channel lock to turn the cam if I need to?

 

 

YES!!!!!!!!!!!!!!!

turn cam? yes channel locks may work also. but if the timming marks are lined up you only barely need to move it if you have to lift the sprocket back up.

 

PS I CANT see your photos!!!!!!!!!

[justin720]

Yes they did rotate the cam but they didn't take it out. From the picture above (can you see them now?) the dowel is in the 12:00 position. Does that mean it's TDC? Can I just use a large channel lock to turn the cam if I need to?

 

 

YES!!!!!!!!!!!!!!!

turn cam? yes channel locks may work also. but if the timming marks are lined up you only barely need to move it if you have to lift the sprocket back up.

 

PS I CANT see your photos!!!!!!!!!

 

Weird about the photos. Well the #1 dowel is in the 12:00 position. When I line up my sprocket with my mark and the dowel, it says I'm in the number #1 position. Should I change that to #2? How do I know how to place the fuel pump drive cam? There doesn't seem to be any way to indicate how it was on before.

 

Here are direct links to the images:

 

Shot of head before removing from block, just after sprocket was removed

http://yfrog.com/jq0325001317j

 

Lower pully lined up to 0

http://yfrog.com/jn0325001239j

 

Mark on chain and sprocket

http://yfrog.com/cc0325001238j

 

Here is a link to the album:

http://yfrog.com/2sp1050454jx

[banzai510(hainz)]

yes the cam dowel will be in 12oclock position

 

take the sproket off and put in #2 position since its a L20. Thae mark on the cahin youll still use.

 

the fuel pump ecentric just put it on .it dont matter it just make the arm go in/out.

 

I cant open those photos. Im at a work computer and say "restricted acess"

If you want me to see it PM you email adress.

[justin720]

yes the cam dowel will be in 12oclock position

 

take the sproket off and put in #2 position since its a L20. Thae mark on the cahin youll still use.

 

the fuel pump ecentric just put it on .it dont matter it just make the arm go in/out.

 

I cant open those photos. Im at a work computer and say "restricted acess"

If you want me to see it PM you email adress.

 

Ok just sent a PM.

 

So it's ok to move the sprocket so my marks don't line up anymore?

[datsunaholic]

If you move the sprocket, you need to move the chain. So, whatever link is currently at the #1 mark on the sprocket needs to be moved to the #2 mark. Should still all line up, just with the different mark. #1 is too far retarded for an L20B.

[banzai510(hainz)]

all else fails go by the video.Thats why I made it so I dont have to write Essays anymore on how to do it.Just put the sprocket to the #2 position like Datsunaholic said. Everyhting else is the same

Youll figure it out.

 

I emaild and now I cant send you photos. I give up.

[justin720]

all else fails go by the video.Thats why I made it so I dont have to write Essays anymore on how to do it.Just put the sprocket to the #2 position like Datsunaholic said. Everyhting else is the same

Youll figure it out.

 

I emaild and now I cant send you photos. I give up.

 

I just emailed you some pics. I was in the garage, sorry to take so long.

 

When I was cleaning the block surface I was realizing that a little bit of gunk was getting into some of the holes. I'm assuming that's not good. So I thought I'd at least drain all the coolant out of the block. That's when I noticed there was no plug in the block! That could account for why I lost all my coolant, interior heat and overheated, but wouldn't explain the massive amounts of white smoke.

 

Here are some more pics:

 

Missing drain plug?

 

Block surface

 

Block surface

 

Cam

 

Antifreeze in head

[banzai510(hainz)]

those block plug never just pop out.

 

I drain the water from the lower rad spout.

 

there was photos of this but now its gone

http://community.ratsun.net/topic/17714-change-your-headgasket-and-not-upset-the-timing/

[justin720]

Thanks again for all the help so far. I'm really close to finishing!

 

Ok here's some pics explaining what I did this morning. One problem is that I wasn't actually able to get the dowel into any of the sprocket holes. The chain just wouldn't stretch enough. When I removed the wood block the chain did get a little bit slack, but it didn't fall down. Is it possible that it came off the lower sprocket or is caught in a weird way on a tooth? I tried moving the cam left and right a little bit to see if I that would help work the dowel in. It allowed me to get the sprocket onto the dowel, but not high enough to get into the hole. Does this mean I need to go through all the work to remove the front cover?

 

Anyway, am I rotating the sprocket correctly?

 

 

 

 

[banzai510(hainz)]

chain not streach?? That why you need to rotate cam slightly to the right.

 

the wood stays in place till the sprocket is installed.

why are the cam tower bolts loose?

[justin720]

chain not streach?? That why you need to rotate cam slightly to the right.

 

the wood stays in place till the sprocket is installed.

why are the cam tower bolts loose?

 

The cam bolts are loose because the guys at the machine shop must have loosened them. I know I didn't.

 

Ok, maybe I'm just stupid, but I can't understand how I can still line up my two ORIGINAL marks (I chose a link at random to make sure it was going back on the same tooth) AND rotate the sprocket, while at the same time keeping the lower sprocket at TDC. Does the cam dowel rotate so it's in the 9:00 position and in the #2 hole?

[datsunaholic]

That's the correct way to reposition it.

 

Hopefully it didn't jump off the lower sprocket and change a tooth. Mine didn't move at all, and basically just slipped on, but had to rock the cam a bit to get the dowel lined up (the cam had gotten turned by the machine shop). Mine was misassembled on #1 as well, with the same junk Chinese cam sprocket.

[datsunaholic]

The cam bolts are loose because the guys at the machine shop must have loosened them. I know I didn't.

 

Ok, maybe I'm just stupid, but I can't understand how I can still line up my two ORIGINAL marks (I chose a link at random to make sure it was going back on the same tooth) AND rotate the sprocket, while at the same time keeping the lower sprocket at TDC. Does the cam dowel rotate so it's in the 9:00 position and in the #2 hole?

 

 

You don't rotate the cam. You just reposition the sprocket, leaving the cam and chain in their original TDC positions. The photos look like you did it right, but there is one worry... you need to tighten the cam tower bolts (not too much! Very low torque here! Rear the manual for the right settings) BEFORE you install the sprocket. In fact you should do that before installing the rockers. Because they got removed they might not be aligned properly and the cam HAS to free-spin or it'll overheat the towers (which have no bearings in them).

[justin720]

You don't rotate the cam. You just reposition the sprocket, leaving the cam and chain in their original TDC positions. The photos look like you did it right, but there is one worry... you need to tighten the cam tower bolts (not too much! Very low torque here! Rear the manual for the right settings) BEFORE you install the sprocket. In fact you should do that before installing the rockers. Because they got removed they might not be aligned properly and the cam HAS to free-spin or it'll overheat the towers (which have no bearings in them).

 

I just called the machine shop. He said he didn't take the cam out, just loosened the bolts and that it was fine to just retorque to spec without worrrying about the rocker arms. Is this ok?

 

I think I was over thinking the sprocket timing issue. This is how I understand it

 

1. Lower sprocket at 0 or TDC in compression

2. Cam dowel at 11:30 position

3. Put the chain on sprocket

4. Put sprocket on cam dowel using the #2 hole in sprocket

5. Check the v groove and line. If they are off then adjust the cam a little bit.

 

If that's right I was getting way to caught up in the marks on the chain thing.

 

I talked with a guy local here who said that using a Fel-Pro head gasket was a really bad mistake and that it will blow within the next couple of months. Is he blowin smoke or what?

[banzai510(hainz)]

He said he didn't take the cam out, just loosened the bolts

 

he had to lift the cam off the rockers otherwise a valve could poke out when shaving the head.

 

that aluminum can strip cause the torq limit is 10-13 pounds ,thats it. you might be fighting a rocker arm with soem tension on there,good luck

 

 

all else fails watch video and do it that way. Now ever if you do have to remove the lower crank bolt you going to be creative to get that bolt loose. Put in gear and hold the brakes?

 

 

just to clearifyl when you make your first X marks should have picked the chain link with the dimple. your sprocket was set to #1 but you still use that location(mark a x on chain) then just pull the sprocket off and otate to #2 position and # 2 dimple will go on the Chain with the mark you made ealier.

 

 

good luck

 

for the felpro head gasket???. I heard mixed results but havent actuaal used them myself

 

bolt that cam down first!!!!!!!!!!! machine shop sould have pulled the rockers off and marked there exact location then maybe pull out the cam if needed.

[datsunaholic]

Yes, just loosening the cam towers alone could throw them out of alignment. And you'll never get the proper torque with the rockers pushing on the valve springs.

 

The way you're SUPPOSED to close the valves to do the mill job is to remove the rockers, not the cam towers. But machine shops get lazy, and L-series heads are weird compared to "normal" OHC heads that have rocker racks.

[hang_510]

:rolleyes: never take a datsun to a chevy guy!

 

Yes, just loosening the cam towers alone could throw them out of alignment. And you'll never get the proper torque with the rockers pushing on the valve springs.

 

...and cam bind if theyre out of alignment.

 

double check the torque w/o spring tension!

 

 

 

 

 

 

i havent used felpro for a long time, but cant recall any issues.

didnt seem to matter brand if the head is flat!

[justin720]

Hmmm. This guys (machine shop) came really highly recommended and seemed really not worried about just retorquing to spec. So am I going to get into a big mess with having to bore cam towers and use a bunch of calipers and such to realign things? Or is it as simple as remove the rockers, tighten cam towers, put rockers back on?

 

I'll be working on it tonight.

[justin720]

Ok I got all the rocker arms off tonight. That was way easier than I thought. When I went to tighten the cam tower bolts I realized that the head bolts were running through the cam towers. So doesn't that mean that I'm not really getting an accurate torque setting since one end is pinned at the 60 lbs from the head bolt? Do I have to undo the head bolts, tighten the cam tower bolts, then retighten the head bolts?

 

Also, when I got all the rocker arms off the cam just slid right out of the towers, which makes sense, but is that a big deal at all? I'm assuming that I just put slide it all the way forward and make sure the dowel is in the 11:30 position.

 

thanks,

Justin