Just bought a 1971 521 for 5 large ($500)

[pwrcat4000]

That hood looks great Powercat.

 

How do you like the L20B?

I love it...... But I had a problem with the valve train #3 intake got bent or something the GD rocker came off and wedged between the spring I set it back up but the valve is bent either that or the seat is broke I have to wait till May to take it to the machine $hop but it is still running I just take it easy. It was awesome until that happened but I think the rear end gear is a little low I need to check the gears on my parts 620 see if it is higher I am still running the 521 intake too!

[pwrcat4000]

[pwrcat4000]

banzai510

 

Shit I just watched

 

 

My l16 may have just cavitated

I ran low on fluid it was over heating and then it lost power. I shut it off towed it home the next day it would still start and run ( ran it for like 20 seconds) Pulled the dipstick thought (thats the shit brings all the boys to the yard) Milky as hell. Could I have just changed the oil and fixed the radiator and kept driving it ?

[Elkie]

If you swapped over to the l16 intake on the l20b, you might have problems with it warming up/starting when its real cold out. Also wouldn't happen to have good fenders on that parts 620 would you?

[Charlie69]

The L20B handles the 3.899 gears out of the early 720 2WD real well.  This is the gear set I use in all my L20B 2WD trucks.  The Z24 in later 720 trucks uses a 3.70 gear set.

[banzai510(hainz)]

Milky as hell meanswater in the oil.

 

find out where its comming from.

Mine was a bad front cover. cause not using good antifreeze. Thats why one has to change it every 3 years.

 

Maybe head gasket

 

change oil and drive it again and see if mils up again.

 

a bad radiator might make it over heat but not cause water in the oil.

[pwrcat4000]

If you swapped over to the l16 intake on the l20b, you might have problems with it warming up/starting when its real cold out. Also wouldn't happen to have good fenders on that parts 620 would you?

 

 

Hey I am a little slow, I guess now.  (I am sure you expect it form a KSU grad) 

I get the tag reference b/c where you are living.  The fenders are not perfect but for kansas they are pretty good here are some old pictures.

 

 

I will post some current pics later today I just used the motor and swapped some other parts out of it so far.  It was a roll over.

hit me up if you are ever around Pucker Brush (Hutchinson, Ks).

and good luck this Wed (not really!!!!) LOL But, you are close enough I could be your new junk dealer. 

[pwrcat4000]

Elkie

 

http://www.motortopia.com/car-pictures/620-34198

[Charlie69]

Before spending money on your point distributor I would replace it with a matchbox distributor.  Easy swap!  Be sure you get the coil and the pedestal with the matchbox.  This is one of the single best upgrades to the L20B.

 

Matchbox distributor with coil and pedestal

 

 

Matchbox Pedestal

 

[pwrcat4000]

Charlie69

Great advice!!! I swapped the coil that came with the 1978 used the matchbox dizzy it was still on the L20B motor. I bypassed the resistor and everything one of the first things I did!! My old points dizzy had vacuum advance problems due to the diaphragm being shit. 

[pwrcat4000]

Just painted up the prop rod for the Ratsun  the oar came with the truck when I bought it.

 

so if your ever up shit creek and you don't have a paddle your welcome!

 

[4perrev]

Good pick up on the truck! Nice buff job. Like what you've done so far. I had a blip on my temp gauge as it ran hot for a while, about where yours is. Changed the thermostat and it fixed the issue. Sometimes they stick also, so you can give them tap on the housing with a screwdrivers backside and it may or may not open for you. The other thing would be a coolant leak. From the sounds of it, youwere loosing fluid into the oil system and the radiator may just have got low enough to cause your overheat condition. Wire splices are good, but make sure you completely clean all connections and then heat shrink the splices to prevent water or oil from getting in there. Love the boat paddle!!!!

[pwrcat4000]

4perev

I should probably start a new tead I fixed all those problems a long time ago I ended up having to take the radiator down to Have it boiled out I replace the thermostat while I was doing it and new hoses. Still was able to blow up the 1.6 liter it didn't help that I was doing probably half a ton of rocks on a trailer and it was low on fluid but it was the water pump actually leaking out of the inspection hole but at that time it had so many leaks I didn't really know which was which. I picked up a 620 a 1979 and swap the Hell20B out of it into my 521 I am still using the 1.6 liter intake and carb of course I use the match box out of the 6:20 and the exhaust manifold which I kind of regret since the 1.6 Manifold seems to flow better according to most of the people on this site. But I wanted a heat riser To help with cold starts. I have managed to bend the valve on the intake on number 3 after adjusting all the rockers I just add them perfectly at least I thought but the number 3 intake rocker went sideways on me wedged And left the valve open enough to bend it either that or it's a valve seat problem I am still driving it on 3 cylinders just around town. I plan on fixing it in May after my last car payment I should have the money to get the head to the machine shop in the meantime it does run as long as I don't push it I have grandiose plans for the motor after I get it solid but I may never get to it thank you for the compliment on the ore/paddle it actually came with the truck since the hood was completely trashed and the spring bar, whatever, mechanism to hold it up was missing. I still have some electrical gremlins, the brakes aren't great, the front end is very loose and probably needs some replacement parts at least some bushings cuz they're gone. But the truck is fine to just drive around just annoying things. It is just a fun toy to play with to me. I am so thankful for this forum though it is definitely not a Pontiac V8

[datzenmike]

The vacuum advance on the 521 is a rubber hose to the port on the carburetor. The only metal line is the fuel line.

 

If you have the L16 intake you don't have a 'heat riser' in the exhaust, the '78 and up didn't have them. Your L16 intake and the '78 and up L20B intakes use warmed coolant from the heads to warm the intake. There is a small hose exiting the intake below the front of the carb and joining the bypass hose from the thermostat housing. Check carefully and see.

 

If your intake were bent and part open it wouldn't run. You would have no intake vacuum at worst or backfiring out the carb when the cylinder fired at the least.

 

 

 

You need to look after your engines more. This isn't a Civic. Driving the shit out of it without coolant... SMH.

[pwrcat4000]

Your right mike
(You're goddamn right) :rofl:

 

I some times call thing the wrong thing what I am calling the heat riser is the shield over the exhaust manifold that, with a 1 1/4 -1 1/2 inch flexible aluminum covered cardbord-ish hose, it plugs in the the neck of the air cleaner.
( I am thinking that a heat riser is a vacuum controlled butterfly valve in the exhaust? It does not have one of those my 1978 ta has one. But that name may be wrong too)

 

The vacuum advance on the 521 is a rubber hose to the port on the carburetor. The only metal line is the fuel line.
Mine is metal I think its copper has threaded fittings on each end. Maybe it is something some one added. Trust me It is way too small to be a fuel line it is (I'm guessing) 1mm in diameter

 

"There is a small hose exiting the intake below the front of the carb and joining the bypass hose from the thermostat housing. Check carefully and see."

 

Yup I have one of those!

 

"If your intake were bent and part open it wouldn't run"

 

 

Man I hope that I am not coming off as a but-head to you, your help has been UN-rivaled with helping me learn this truck.

But I have to disagree with you there Mike.
I have accidentally run the truck with 1 plug wire (#4-the back cyl) off and this problem, but it will not run right, or idle at all, and it requires, a lot of work, to barely move the truck but the engine does "run".

It is firing though the carburetor, or would be, if the plug was not so fouled that it would fire. Like I said in our earlier discussions it is "open" but only 1/8 - 1/4 inch or so, it will go down more, but not up more. Like you said either the seat is pulled out of the head or bent valve. Either way It will be at the machine shop soon.

 

I am curious, since I will most likely have to buy a valve, or all of them? Are there still valves available? Am I getting ready to go on a Google treasure hunt?

[datzenmike]

Then we agree it would backfire through the carb otherwise. Stop driving and you can probably still fix this for a head gasket and an old intake valve from someone before it gets pounded.

 

Is your vacuum advance going to the carb or the intake?

[Elkie]

Rockauto has intake valves for $6.

[4perrev]

Yep, with these kids here! Park her until you can get into the engine and make it right. Nothing worse then blowing something up when you're not at home. You have other cars to run around until she's right. Last car payment? Funny until I read all your cars. If you old had one payment left on the Datsun, you financed her wayyyyyy to long (about 40 years too long)!!!!

[pwrcat4000]

yes, 4perrev LOL I refinanced my 1978 TA to get a light restoration (rust removed) all the rest of my stuff is paid for.

 

Elkie,

Thank you I have been AFK

 

 

datzenmike yes that is the plan

as to the vacuum I will have to look to be sure, (my memory is not what it used to be) but I think it is coming off the passenger side of the carb

[bilzbobaggins]

My 521 has the hard vacuum advance line with the threaded fittings as well

[pwrcat4000]

anybody know the part number on the chain tensioner tool?

[bilzbobaggins]

Powerbuilt 648831

[pwrcat4000]

Ok Valve and tool are being shipped any tips about the process.

I will be pulling the head my self and replacing the gasket (I bought an engine gasket kit for the previous swap so i have all the gaskets).

THE PLAN

Do all the safety crap DC battery, block wheels, truck in neutral clamp/plug gas line ect ect.

 

Drain coolant and reuse later.

It is only 2 months old since that is when I replaced the water pump.

 

Unbolt the intake and exhaust manifolds from the head i am going to try and leave as much stuff as possible connected and just lay them aside.

 

Remove the valve cover,

 

Clock #1 to TDC I am going to take pictures of the cam gear location and all the lobes and the chain and use a yellow grease pencil and am hoping there is some sort of key-way or alignment markings too. I am the most scared of timing issues.

 

Insert the chain tensioner tool,

I am hoping the tool will help me keep the engine in time. The timing is the scariest thing for me. I have only ever worked on push rod GM V8s.

 

Unbolt the cam gear and set it aside tring not to to disturb the chain (scary as Shite)

 

Unbolt the head and lift it off (any weird or hidden bolts??)

 

Remove the bent valve on the bench

I can borrow a air powered valve spring compressor from the local auto parts guys. I assume it is no different than the valves and springs in my 78 firebird (it uses 2 little round tapered keepers and spring pressure to hold the valve).

I was planning on leaving the other valves alone I adjusted them about 2 months ago (.08 and .10 cold)

 

Pray that it is not the seat

because I really don't want to use a machine shop unless I have too.

 

Insert the new valve. with assembly lube/paste on the stem (I have some from my T/A re assembly).

(Do you think I can get away with just replacing it or do I need to use some abrasive paste?) I don't remember what the paste is called, but remember twirling some valves in small gas engine class in 1984 for some reason. I had the machine shop do a 3 angle on the valves on my trans am soooo.

 

Once the valve train is all back together.

 

set gap on new valve 0.08

I am sure I will need to check this ever 3k? miles or what ever you all recomend since it is an new part contacting old parts.

 

Recheck the clocking on all the rocker guides as I think that is what caused the problem in the first place.

 

Set the gasket on the block

I assume there are guide pins or something.

Will I need to use "gasket dressing"? on the head gasket?

 

I will look thought the forums for torque specs and tightening order.

Unless some one wants to post them in this thread.

 

Reverse the process

 

I have new intake and exhaust gaskets is the intake just dry fit?

look up torque and tightening specs for the manifolds.

 

I am going to leave off the valve cover for now

 

 

Reconnect gas see if it runs for a few seconds at most.

If I have issues I am going to stop right there and you will see the post LOL

 

Hopefully no issues and it fires and runs smoothly

Rad Fluid and button it up. I will probably do an oil change too.

 

OK tell me what i left out guys

(this usually means I am posting for datzenmike my ratsun yoda)

[hobospyder]

paste stuff probably for lapping the valves

 

no sealant on head gasket or valve cover gasket. i think on the second

 

mike should be along with better info than i have

[4perrev]

Sounds all good. You should watch hanzi's video on YouTube for setting timing. It is much easier than the printed Nissan version. Makes sense before you get in it. Just a thought.