79 620 King cab, Cali Import now in the UK

[Danalive]

Hi Folks, long time lurker but finally picked up my first Datsun, a 79 620 king cab with a l20b 5 speed and air con. 

looks to have last been on the road in 2003, was imported into the uk 2 years ago. 

 

It's got a few dents and a few spots of rust but overall a solid starting point, 

plan is to get it on the road by March hopefully, first of all i want to get it running.

 

this is the current state of the engine, someone has removed the cam sprocket and wedged the chain tensioner, 

 

it doesnt look to be at TDC, i cant see any marks on the chain, and if im correct cyl 1 cams should be at 10 & 2? the bottom pulley doesnt have a notch lined up with the sawtooth timing thing, i pulled the distributer and the oil pump gear rod doesnt look to be in the correct position or TDC either:

the top part of the chain thats exposed is a bit crusty and the valve springs on cylinders 1 & 2 also look to be a bit rusty.

though i was hoping for a quick fix with this, im thinking that the best course of action would be to remove the front cover and fit a new chain, tensioner and guides and also replace the valve springs, though should i just pull the head and rebuild it? would be a first for me but im confident enough to give it a go. 

 

its a bit of an oddity because someone has repainted the engine bay and the block, the engine mounts look new, the driveshaft has been disconnected, its like someone pulled the motor, painted and then gave up at this point. 

 

but yeah any suggestions on the best move forward would be much appreciated.

 

[datzenmike]

Pictures are not showing up at the moment, will try again later.

 

A little rust on the valve springs won't hurt anything.

 

Front cam lobe is the exhaust and it should be at or near 2 o'clock, next one back is the intake at 10 o'clock.

 

The marks on the chain that align with the dots on the cam and crankshaft sprockets only line up when installing. The timing chain is approximately 100 links long divided by 10 links worth on the crankshaft sprocket so once engine is turned they randomly line up properly maybe every 10 turns???? If there is an odd number of links it could be a thousand turns. I don't know.

 

It's hard to get the timing cover off with the oil pan  and head still on. It is do-able. Not much sense rebuilding the head and then find out the head has to come back off to put rings in it. I would get it running first and evaluate it. Way easier to do all this with the engine out or apart for a rebuild.

 

 

 

[Danalive]

Thanks for the reply Mike, I’ve fixed the pictures, I’ll get a better one showing the rust on the valves etc

 

thats makes sense about the chain links.

 

Right get it running in place, diagnose what’s wrong and go from there. 

What about refitting the cam gear? Just do it and pray? Or are there things I could check to make sure I don’t get any interference? 
 

 

[datzenmike]

 

#1 cam lobs are downward meaning both valves are part open. This would be the overlap between exhaust and intake cycle so near 180 out and why you can't fine the timing mark on the pulley.

 

 

Definitely 180 out. See the large and small half moon on the oil pump/distributor drive spindle? Small should be on the left or to the front, like this...

 

 

 

You have the sprocket? Put the sprocket back on, take wedge out, turn the engine to the TDC on the compression stroke (cam lobes up valves closed) line the notch on the pulley with the ignition timing scale O and then look to see that the spindle is now at 11:25 position. It probably is but if not it can be re-adjusted.

 

Middle picture... shows red RTV all over the top of timing cover so it has been out but the head left on so chain may have been replaced or it's an attempt to correct the spindle position (wrong way BTW) There's likely RTV at the front of the oil pan as well.

[Danalive]

I have the sprocket, attempted to get it on yesterday but i fear the tensioner has popped out, the wood block doesnt go down far enough to block the tensioner, i didnt have a decent torch to hand as its currently in a friends storage yard.

Ive made a rod and have a pry bar so will attempt to push it back in enough to get the sprocket back on. 

 

 

 

[Danalive]

The truck came with no keys, so i pulled the passenger side lock barrel and managed to obtain a key code, ordered a Key from https://www.key2code.co.uk/ which fits the door locks, but doesnt even go into the ignition barrel, so im assuming the barrel for the ignition was changed at one point as i can slide a vw key further into the barrel than the new key for the door locks. 

the jobs keep adding up, the passenger side will lock on the key but the exterior handle doesnt open the door, the drivers side door will lock but wont unlock using the key, but at least that door handle works.

 

managed to pick up a chiltons manual of ebay uk which is going to come in handy.

 

something was storing their dinner in the radiator

[datzenmike]

The wood block doesn't block the tensioner, it's a wedge that is pounded down jamming the chain against the chain guides. It's not ideal but if you are careful it works.

 

The '79 620 bible is the Nissan FSM. (factory service manual) It's almost 2" thick and nothing is wasted covering all the years of the 620 that you don't have. It's all '79 and all the diagrams and pictures, facts and figures are copied (including making mistakes) into the Chilton's. Haynes is another 'manual' that only covers the '73-'77 620 and then jams a few pages in the back as a supplement for the '78 and '79.

[Crashtd420]

Personally I'd take the front cover off and do it the right way with everything at top dead center to start.... then you know for sure it's all correct.... 

Then you can have a look for anything suspicious in the oil pan and reseal everything properly..

Looks like you need to flush the radiator too...

[Danalive]

On 10/14/2022 at 12:47 AM, datzenmike said:

The wood block doesn't block the tensioner, it's a wedge that is pounded down jamming the chain against the chain guides. It's not ideal but if you are careful it works.

 

The '79 620 bible is the Nissan FSM. (factory service manual) It's almost 2" thick and nothing is wasted covering all the years of the 620 that you don't have. It's all '79 and all the diagrams and pictures, facts and figures are copied (including making mistakes) into the Chilton's. Haynes is another 'manual' that only covers the '73-'77 620 and then jams a few pages in the back as a supplement for the '78 and '79.

Is there a link to a pdf for the 79 manual? I found one for 78 online but not 79.

 

[Danalive]

22 hours ago, Crashtd420 said:

Personally I'd take the front cover off and do it the right way with everything at top dead center to start.... then you know for sure it's all correct.... 

Then you can have a look for anything suspicious in the oil pan and reseal everything properly..

Looks like you need to flush the radiator too...

That’s the plan now, the tensioner has definitely popped out.

ordered up a timing kit and a few parts from rock auto, who deliver to the uk for a reasonable price and reasonably quick too, Datsun parts are pretty much unobtainable in the uk. 

[Danalive]

pulled the radiator, gave it a shake to remove the debris in there, several handfuls of acorns came out, will give it a proper flush through before refitting

started stripping the front of the engine to get to the timing cover, which at first though was quite daunting, but i had everything off and the cover unbolted in a few hours. 

 

 

water pump has seen better days

quite a bit of crap built up inside, 

 

timing cover came off with a bit of very gentle tapping, 

removed the tensioner and got the sprocket and chain back on, pulled the plugs and tried to turn it over by hand, id previously poured some ATF + acetone into the cylinders to free them up.

at first it wouldnt budge, i feared the worst, thinking the whole thing was seized, then suddenly it started moving, spurting out the ATF mixture, got it timed up roughly and was quite pleased that it was moving. 

 

got a new timing kit so that'll go on next and i'll put this all back together

 

the carb is  rusty and seized, im going to put on a new weber 32/36 DGEV and remove the emissions systems.

 

scored this nos ignition barrel off ebay for £5, it's only got 3 connectors on the back, the one in the truck has 5, but i'll pull the barrel from the new one and put it in the truck one. 

[Stoffregen Motorsports]

The cam looks like an aftermarket cam. The telltale signs are the grinding marks on the face (where the sprocket/gear attaches) and the shape/color of the lobes. Are there any stampings on the back of the cam? Or are there any casting numbers along the length of the cam? Castings would be U20, U60, etc. Stampings with be A, B, C, etc. If it's an aftermarket cam, you may want to identify it before trying to run it. If it's big, it will need stiffer valve springs and the rocker geometry needs to be checked and possibly adjusted with lash pads.

 

If the truck has been sitting for more than a decade, be prepared to replace the entire braking and fuel systems. Hoses swell and deteriorate. Master/wheel cylinders/calipers get moisture in them and seize. Fuel pump diaphragms get dry and tear, and then the fuel lines and tank will also have a bit of crud in them from moisture and/or insects (mud bees). Even if you get all these parts to work without replacing them, it's a matter of time before they show their ugly problems.

 

Nice truck.

[Ooph!]

On 10/15/2022 at 6:16 AM, Danalive said:

Is there a link to a pdf for the 79 manual? I found one for 78 online but not 79.

 

 

I have not seen one, the attached threads link will have the 79 wiring diagram that will help.

 

 

[datzenmike]

Cam

 

Borrow a caliper or micrometer and measure the cam base circle, the narrowest width off the lobe. A stock cam will be 33.27mm if less, then the cam may have been ground down to make the lobe actually higher.

 

Subtracting the base circle from the diameter across the high point of the lobe gives you the lift of the cam. Multiply by 1.5 and you have the maximum valve lift. L20B valve lift is 0.413" or very close to 10.5mm.

 

Doesn't appear to be ground down but measuring makes sure.

 

 

This L20B was obviously apart by a GM owner.

[Danalive]

6 hours ago, Stoffregen Motorsports said:

The cam looks like an aftermarket cam. The telltale signs are the grinding marks on the face (where the sprocket/gear attaches) and the shape/color of the lobes. Are there any stampings on the back of the cam? Or are there any casting numbers along the length of the cam? Castings would be U20, U60, etc. Stampings with be A, B, C, etc. If it's an aftermarket cam, you may want to identify it before trying to run it. If it's big, it will need stiffer valve springs and the rocker geometry needs to be checked and possibly adjusted with lash pads.

 

If the truck has been sitting for more than a decade, be prepared to replace the entire braking and fuel systems. Hoses swell and deteriorate. Master/wheel cylinders/calipers get moisture in them and seize. Fuel pump diaphragms get dry and tear, and then the fuel lines and tank will also have a bit of crud in them from moisture and/or insects (mud bees). Even if you get all these parts to work without replacing them, it's a matter of time before they show their ugly problems.

 

Nice truck.

I'll take a look at the cam and see if theres any markings on it and report back.

 

im fully expecting to have to replace most of the fuel and braking system, will definitely be replacing all rubber hoses. 

main focus at the moment is to get the engine running, then sort out the fuel system and then the brakes. 

[Danalive]

3 hours ago, datzenmike said:

Cam

 

Borrow a caliper or micrometer and measure the cam base circle, the narrowest width off the lobe. A stock cam will be 33.27mm if less, then the cam may have been ground down to make the lobe actually higher.

 

Subtracting the base circle from the diameter across the high point of the lobe gives you the lift of the cam. Multiply by 1.5 and you have the maximum valve lift. L20B valve lift is 0.413" or very close to 10.5mm.

 

Doesn't appear to be ground down but measuring makes sure.

 

 

This L20B was obviously apart by a GM owner.

i'll see if i can borrow a set of calipers, thanks for the explanation, suddenly makes sense when folk talk about regrinding a cam. 

 

yeah theres rtv on everything, ive got a gasket kit so will remove as much as possible. 

[Danalive]

little update i measured the cam and its 33mm at the thinnest part of the cam and 39mm at the highest, not sure if this makes a difference, but i measured 2 different lobes and i didnt even check if they were intake or exhaust, so i'll remeasure properly next time im with the truck, i was passing by so thought id get a quick measurement.

 

heres some photos of the markings on it:

 

couldnt see anything on the back of the cam, 

 

 

 

[Danalive]

new timing chain fitted up, lined up the dots for the dark links, sprocket on no. 2, new chain guides and tensioner, was pretty straight forward having read up about it on here and watch hainz's video. got the front cover back on and removed a few EGR bits and the original carb. 

 

 

Water pump i ordered was for the wrong size fan and had a bolt where the one  that came on the engine had a locating pin. another one on the way from rockauto as i couldnt find one in the UK, 

 

 

[datzenmike]

33mm is almost exactly what I have so stock cam. I had just over 40mm for on the lobes.

 

 

This is close to perfect.

 

 

That EGR manifold will need a block off plate to seal it up. You can remove the EGR manifold on the intake and make a block off plate for it but for pity's sake keep the PCV valve operational. With a little work I converted a '79 L20B EGR intake

 

Started with...

 

 

With some grinding and tapping and some JB weld got  the '79 to look like an early L116 intake.

 

 

You can cut those air injection tubes off and fold them over so they don't leak, or better yet pull them out as they stick down into the ports 4-5" and weld the holes closed. Another option is...

 

 

 

[Stoffregen Motorsports]

I am 99% sure that CWC is an aftermarket cam billet.

[datzenmike]

Well if it is I have one on an old '75-'77 U67 head. My only other easy to get at head says JAPAN in that spot and no cwc. I have 3 other engines with heads but not easy to get at and the one on my 710.

[Stoffregen Motorsports]

Not to beat a dead horse, but there are things that need to be checked and/or verified before running a motor with an unknown cam. If it is a custom cam, there should be etching on the back of it, usually stamped or with an electric pencil. As mentioned before, the grinding on the face of the cam is indicative of an aftermarket cam.

 

What caught my attention was the shape and color of the cam lobes.

[datzenmike]

On 11/1/2022 at 9:05 AM, Danalive said:

little update i measured the cam and its 33mm at the thinnest part of the cam and 39mm at the highest, not sure if this makes a difference, but i measured 2 different lobes and i didnt even check if they were intake or exhaust, so i'll remeasure properly next time im with the truck, i was passing by so thought id get a quick measurement.

 

 

 

 

On 11/1/2022 at 12:05 PM, datzenmike said:

33mm is almost exactly what I have so stock cam. I had just over 40mm for on the lobes.

 

 

Mine

40mm - 33mm = 7mm X 1.5 is 10.5mm or 0.413" which is exactly the valve lift on an L20B cam.

 

His

39mm - 33mm = 6mm X 1.5 is 9mm or 0.3546" (seems a little low)

[Danalive]

update time, been waiting on some parts and on the weather to get things done. 

 

thank you both for your input on the cam, i checked again, and again with the calipers and it is 39.5mm x 33mm, which would be 9.75mm lift, not quite stock l20b numbers, there is no markings on the back of the cam.

 

tidied up for the weber swap, the air tubes that go into the exhaust were stuck in solid, i cut the tubes off so i could get a 17mm socket on the end, that go 1 out before they rounded over, the next one came out with some vice grip persurasion, the last 2 required a good bit of heat before they finally started to budge.

 

I tried a few options for plugging the airtubes into the exhaust someone else had suggested "3/8th flared" but i couldnt find anything that matched, popped down to the local bolt store and they matched it up to M16, 1.5 pitch and they had some tapered pressure plugs that went straight in. 

also for plugging the EGR tube (no 15 in the diagram) that runs from the exhaust up to the egr block on the intake they matched up to M22 1.5 pitch and supplied a tapered pressure plug for that aswell. i havent seen the size mentioned before so hopefully this will help someone in the future. 

question for mike, you show part no. 10 here threaded into your intake, is this neccesary to keep? i cant recall what it was connected during dissassembly and i see youve got it on the intake picture you posted above.  

i was planning on making a plate like this to retain the PCV 

 

 

 

purchased a new clutch master from rockauto along with some other bits, went to fit, realised it was the wrong bolt pattern for mounting, new on top, old one underneath

 

so i tore them both apart and reassembled the new parts in the old housing, the internal component were the same, rebuild kits might be the way forward instead of the parts cannon. 

 

 

 

 

 

next issue is connecting the exhaust, its all there, but the  semi triangular plate that secures the exhaust on to the manifold is wedged below the torsion bar and i cant get it up through the gap between the torsion bar and the block, thinking i'll have to disconnect the torsion bar, slide it back so i can get the trianglular thing up and mounted unless theres something im missing. 

 

 

 

 

[datzenmike]

 The one they gave you will fit the D21 Hardbody, 2 generations of truck later than the 620. Figures. Good idea swapping the parts.

 

Try prying on the block with a 2x4 The rubber isolator on the mount will give some, maybe enough to get the triangle thing past the torsion bar.