'71 GOON L20B Swap

[SHAMUS'WAGON]

I have had my '71 510 wagon for ten years. It was purchased from my parents for $1.00. It was a pretty good deal since I didn't have the $5,000 it would cost me to buy the '72 Buick Skylark from him.

 

 

It had a Blown rear main in the L18 that was in it when I started driving it. I had to put a half to a full quart of oil a day in it. I decided to put another engine in it, but all we could find at the time was an L16. The yard I bought it from said they had two in stock. I could buy one for $150 or both for $200. I really wish I would have taken them up on that. Anyways, ten years and almost 200,000 miles later. I've discover, or rather finally figured out, that I have had a valve pulling through it's seat the entire time I've had the motor. I explored my options with rebuilding the L18 I still have laying around, but it's been floating around with me unpreserved for ten years.

 

I opted for getting another motor. While searching craigslist for a motor or donor car. I found a listing for a $40 L20B. The reason for the price tag is I have to put it back together.

 

 

So, long story short. Got the block all cleaned up and painted.

 

Now I'm cleaning off the gasket surfaces, and this is what I find.

 

I'm wondering if this something I can slap some JB Weld on? Or is my project screwed because I can't afford to pay someone to fix this? HELP! This is located in the cylinder head bolt hole between Cylinders 2 and 3 .

[datzenmike]

I'd run it if just a DD. Lots of L series out there driving around with cracks it you take them off the road and take apart. A crack means that the stress was relieved and does not always mean it will get worse. There's no indication it was leaking. Where's the water going to go anyway? Into the bolt hole that has a bolt in it? Up through the head hole to the bolt top and washer that is torqued down with 60 ft lbs? Use a good gasket and forget it. OR huck it. You're only into it for $40 and you still have the head and internals for spare.

[DISLEXICDIME]

When my l20 was cracked just like that it kept blowing head gasket's

[banzai510(hainz)]

Love your wagon ,Pefect color!!!!!! Love the Hubcaps

 

I had a block that had this also. Previous owner had no proplem before with the motor but I throew it away anyways as I had another block.

But its up to you if you want to run it.

 

datdoug has a few blocks he was tryin to get rid of. PM him but he lives above Bremerton

[SHAMUS'WAGON]

I'd run it if just a DD. Lots of L series out there driving around with cracks it you take them off the road and take apart. A crack means that the stress was relieved and does not always mean it will get worse. There's no indication it was leaking. Where's the water going to go anyway? Into the bolt hole that has a bolt in it? Up through the head hole to the bolt top and washer that is torqued down with 60 ft lbs? Use a good gasket and forget it. OR huck it. You're only into it for $40 and you still have the head and internals for spare.

 

Is there anything I can do about the pitting near the water hole? Is a touch of JB Weld a bad Idea? I just don't want to invest all the time into something that's gonna give me trouble from the get go. Can anyone tell me what I should be using to clean the deck surface?

 

 

 

[Farmer Joe]

well back in the day when i rebuilt the motor in my luv, i just took a foot long piece of 2x4 and stapled some sandpaper to it. kinda like a body shop would do for big areas.

 

anyways, took the board with sandpaper to the deck of the block and started sanding. i went from coarser sandpaper to fine after getting the headgasket leftovers sanded off.

 

reason why i did the longboard was to keep from making low spots in the block by sanding in one area. i put a good 6 hours into it and i got a surface that looked almost like a machine shop job.

 

so you might just take some time and sand the deck of the block and maybe you can clear a little but if that boogered spot up...

[SHAMUS'WAGON]

well back in the day when i rebuilt the motor in my luv, i just took a foot long piece of 2x4 and stapled some sandpaper to it. kinda like a body shop would do for big areas.

 

anyways, took the board with sandpaper to the deck of the block and started sanding. i went from coarser sandpaper to fine after getting the headgasket leftovers sanded off.

 

reason why i did the longboard was to keep from making low spots in the block by sanding in one area. i put a good 6 hours into it and i got a surface that looked almost like a machine shop job.

 

so you might just take some time and sand the deck of the block and maybe you can clear a little but if that boogered spot up...

 

Now I don't feel like such a goober, because that's what I have been doing. With the sanding should I work front to back, or circular motions? JB WELD good Idea... bad idea? I've heard of people using it to save engines. Never heard of anyone using it on the head gasket surface though. Also wondering if anyone has a the Flex plate ( fly wheel) I need to bolt this L20B up to my BW automatic? I haven't hit the yard yet, but I think I got time soon.

 

 

[SHAMUS'WAGON]

Love your wagon ,Pefect color!!!!!! Love the Hubcaps

 

I had a block that had this also. Previous owner had no proplem before with the motor but I throew it away anyways as I had another block.

But its up to you if you want to run it.

 

datdoug has a few blocks he was tryin to get rid of. PM him but he lives above Bremerton

 

Thanks, but this is what it looks like ten years later

 

 

 

 

[banzai510(hainz)]

flex plates need a adapter at the end of the flywheel. if L 20 its a 6 bolt.

[SHAMUS'WAGON]

flex plates need a adapter at the end of the flywheel. if L 20 its a 6 bolt.

 

Would you care to elaborate?

 

 

 

[SHAMUS'WAGON]

flex plates need a adapter at the end of the flywheel. if L 20 its a 6 bolt.

 

An adapter I can find on another car? Or an adapter that I have to make?

 

 

 

[hang_510]

if its near the water jackets, JB weld should hold up to a DD.

i wouldnt trust it near a compression area

 

i use a long wetstone to surface an already flat block.

 

An adapter I can find on another car?

most people pull em and scrap em.

someone should have one stashed... i have one for a 5 bolt crank(L16-L18)...

[SHAMUS'WAGON]

Anybody wanna go another round of, "Run it or Scrap it." I quit workin on the block, and decided to check out the cylinder head. Figuring If I get a good head out of the $40 I'm good with that. Cleaned cylinder 2 first. Just because it was the worst. It cleaned up good, so I went on to cylinder 3. This is what I find beneath.

 

 

 

Then on to cylinder 4, and found an Identical crack there. So what I'm wondering is. Will this crap run until I can find something else CHEAP? Or are the Block and head worth there weight in scrap because the fucker won't run? Forgive me if I sound novice. I've taken a lot of motors apart at the salvage yard, but I never had to worry about putting them back together. Will this crap work temporarily for a daily driver?

[LenRobertson]

An adapter I can find on another car? Or an adapter that I have to make?

 

To elaborate on the flex plate adapter - This is round spacer plate on the back of the crankshaft the flex plate bolts up against. I'm remembering it being about 1/4" thick. The flex plate is thinner than a flywheel. The adapter just makes up for the difference in thickness. It is a tight slip fit onto the back of the crank. A couple of small pry bars or large screwdrivers will pry it off the shaft. It looks at first glance to be part of the crank,but is removable. There will be a 5-bolt spacer on your L18 crank, but if you're going L20, you need a 6-bolt to go with the 6-bolt flex plate. You can try prying the one off your L18 just to see what it is, although as rusty as that engine looks, it may not come off easily. Anyway, if you go to wrecking yards looking for a 6-bolt flex plate, don't forget to get the adapter off the adapter on the crank. Check any flex plate for cracks, especially from the bolt holes. I don't know if Datsun plates ever crack, but I've seen other makes crack.

 

Bummer on both block and head being cracked. It sounds like you might be okay running the L20 block (if cylinders, pistons, crank are all okay), but I'd be afraid of the cracks in the head between seats. I'd be heading to Pull n Save looking for another head. And yeah, you might go to the trouble of pulling another head to find it is cracked, but I don't think head cracks are really common, so the odds are in your favor. Up here in Spokane, Pull n Save has a $25 core charge on aluminum heads, so your cracked head is worth that, if your P&S charges a core charge. Remember to try to find a head with rectangular exhaust ports to mate with your L18 exhaust manifold. A lot of the late L20 heads had round exhaust ports. You should get a tap to clean out the head bolt holes on your block, too. Maybe someone else can give details on what works best for that.

 

Len

[datzenmike]

Would you care to elaborate?

 

Without spacer.......................................................... with spacer

 

They look like this when off. Top right one goes on crank. The others (only one) go behind the flexplate to sandwich it.

 

 

 

This is the engine side of the flex plate, the spacer is already on it. It has a forward lip that fits around the crankshaft end and may need to be pried off when removing. The other one leaning against it goes on the transmission side to sandwich the flex plate.

 

You have to have this on the crank!!! Very important or the flexplate will be forward at least 1/8" causing starter engagement issues and possible torque converter fitment problems.

 

If using an automatic motor be sure to REMOVE it if installing a standard transmission flywheel. Or it won't go on.

 

.

[banzai510(hainz)]

man you have had some bad luck finding motor blocks.

 

I think your in a rush. Take your time and parts will find you.

I have SEEN many a PERFECT L motor block go to the dump cause people are out of room.

 

Like I said Datdoug had 5 blocks for sale.

[hang_510]

man you have had some bad luck finding motor blocks.

:console:

 

im right there too :(

[SHAMUS'WAGON]

Well, now that it's two months without any progress on the L20B. I've opted for throwing another dirt cheap L16 in there. Picked this one up for a hundred bucks from this guy who had a driveway full of Datsuns. The guy said in ran 2yrs ago when pulled. Right when I looked at it I noticed that the timing mark is on the wrong side of the timing cover wondering WTF. I expected the Tab was just put on wrong by mistake. Then I get home and line up the marks, and this is what I get

 

Timing mark @ TDC

 

And the distributor @ cylinder 1

 

The cam lobes are @ 10 and 2. So it seems that someone timed this engine wrong. Just wondering if anyone knows how I can fix this.

[banzai510(hainz)]

olddatsuns.com

watch my vid. I think I mention that the sawtooth timmingplate can be on one side or the other from the factory.

 

On that L16 distributor put the cap on there. and then put #1 plug wire on there where the rotor points then go 1 3 4 2 fire order. then the rest can be dialed on adjusting the timming plate. always use TDC as your reference and the oil spindal at 11.28 postion.

 

Remember other L series dists can be different so If you get another dizzy just make sure to have the matching timming plate and pedastal(a SET) then they can be install in any L series motor but when they lock down the rotor might be in a diferent posistion. But since you will have you motor at TDC you just put the plug wire #1 there and go 1 3 4 2 counter clock wise fire order.

 

On that dizzy you hav eits a duel point. the main point has the bigger cap on the outside. I dont even use the 2nd set of points myself. best to upgrade once you get it started and running.Point youll use the point coil and ballast resisitor.