temp and runability questions

[moparvwfreak]

on a 73 L16 620 where should the temp be??? when i ran water, just water, init the temp was around 1/2 way up the gauge. with a good 50/50 mix it goes between 1/2 to 3/4 of the way up the gauge. any ideas why it would do this??? water pump, thermostat, rad cap are new and the rad is a used one but not leaking. and yes pressure is good when its hot.

 

now for the runability issue. on a flat or down hill in 1st gear no issues. but if i am on a hill going up the truck will bog bad enough it almost dies. i could floor it and it'll still bog, spit and sputter till i am at around 10mph or so then it picks right up and goes like mad. ideas???

 

i know the timing is off but i cant adjust it anymore. its retarded as much as possible to get it close to what it SHOULD be timed at. mine is around 10* and spec is 5* if memory serves. valves are adjusted to .008 in so all is good there. i am gonna check the exhaust ones. i think those may be to tight.

 

thanks guys!

[ggzilla]

Temperature should be between 1/2 and 3/4. Typically it will be right about 1/2 way with a 180 degree thermostat.

 

on hot days (over 80) you may see the temp climb higher than normal. This is not a problem, Datsun engines can run right up to the H line without any damage. Fitting a larger radiator will allow it to stay same hot or cold days, but is not necessary.

 

 

Running uphill your engine bogs? Most likely teh fuel bowl level is too high. Check the carb's sight glass (most L-engines have them) and make sure it is on the dot or line -- not above it.

[datzenmike]

10 degrees for an L16 truck.

 

With engine off look down the carb and work the throttle. You should see a strong squirt of fuel in the barrel closest the valve cover. If weak or not there your accelerator pump is bad. Without it the engine will stumble above idle when you step on the gas.

[moparvwfreak]

Temperature should be between 1/2 and 3/4. Typically it will be right about 1/2 way with a 180 degree thermostat.

 

on hot days (over 80) you may see the temp climb higher than normal. This is not a problem, Datsun engines can run right up to the H line without any damage. Fitting a larger radiator will allow it to stay same hot or cold days, but is not necessary.

 

 

Running uphill your engine bogs? Most likely teh fuel bowl level is too high. Check the carb's sight glass (most L-engines have them) and make sure it is on the dot or line -- not above it.

 

ok cool. i was curious about that. kept turnin the HEAT on to bring it down and it wasn't working the best. now i know and wont worry about it. as for the float level, i have the clear front cover adn tis right on teh ball.

 

 

10 degrees for an L16 truck.

 

With engine off look down the carb and work the throttle. You should see a strong squirt of fuel in the barrel closest the valve cover. If weak or not there your accelerator pump is bad. Without it the engine will stumble above idle when you step on the gas.

 

i will check the timing again tomorrow and the accel pump. but the ONLY time it stumbles is going up hill from a stop. so i dunno. maybe i am weird.

[motavated]

Do you have to purge the system for air for these Datsun?

[420n620]

you say ur valves are adjusted @ .008 is to tight. I set my valves @ .008 intake .010 exhaust once and it ran like crap so I put them back @ what het manuel says, .010 intake .012 exhaust and it ran a hell alot better, better performance and better gas mileage.

I talked to a pro engine builder about valve settings and he says that car manufactures do exterm research on what is the best valve setting for a reason - it all about het geometry.

I know sum might not agree but do what you want.

you might want to make sure you don't have a air lock in ur cooling system, you will have to BURP it.

Also even if you put in a new thermostat, you always want to check it before you install it. My neighbor put a new one in a truck and it turn out to be bad. All you have to do is put it in boiling water and make sure it opens all het way.

good luck

[moparvwfreak]

i was going off my FSM when i adjusted the valves. it called for .008 intake but i misread the exhaust. it was .010 but i read it as .008. no big i will readjust those tomorrow. as for the thermostat i did check it when i installed it as i didn't have one in there when i got the truck i make sure all my thermostats and temp switches work before i install em. that way if its bad i can take it abck and get a new one :D oh and i do know about burping the cooling systems. i own VWs.

[datzenmike]

oh and i do know about burping the cooling systems. i own VWs.

 

:D:D:D

 

There are two fuel circuits at work here. Idle and the primary barrel. Idle air flow is very slight, and it has it's own metered orifice at the closed throttle plate. When you step on the gas pedal the throttle plate moves away from the idle orifice, removing the vacuum, and transitions to the main primary barrel. The primary relies on a larger amount of air past the venturi to draw the fuel out. The engine isn't turning very fast and there isn't much air flow, thus the venturi vacuum will also be low and so it takes a while for it to build and start drawing fuel. At this point the motor will run very lean and stumble. The accelerator pump gives a much needed shot of raw fuel to help the engine through this transition. Most, but not all, carbs work this way in some manner.

[banzai510(hainz)]

i know the timing is off but i cant adjust it anymore. its retarded as much as possible to get it close to what it SHOULD be timed at.

 

Maybe ck this out first????????? if the dizzy is clocked all the way to one side then maybe the faster you go it the dizzy goes out of adjustment/timming.

 

put motor on TDC ,see if the oilpump dist shaft is at the 11.28 position. If yes then install the dizzy and make sure the rotor points on a plug wire pretty much right ON.

 

also there is a 8mm bolt that hold the timming plate to the dizzy and you can move it more adv or retard so you can cent er it better.

 

Im sure the valves adj isnt the real proplem but might help. I adj mine to .006 intak and .oo8 cold.

 

 

PS anti freeze gives it a higher boiling over temp and prevents cavitation or for us ruining the Front cover/corrosion. USE it but straight water cool better I believe.

 

time motor first, buy a 160deg 54mm stat(generic) then buy a New rad. as they are still cheap for a 620

[zed]

I've read that pure water is the most effective coolant - because it absorbs the most heat before boiling. When anti-freeze (ethylene glycol) is added to water, it lowers the boiling point. But of course pure water causes rust, and freezes at 0 degrees Centigrade.

[datzenmike]

Ethylene glycol will actually raise the boiling point of water. Pure ethylene glycol boils at 388F. This will allow the engine to temporarily run hotter than boiling point of just straight water.

[racerx]

Should be about 180 - 190, but I think you said it timing.

 

 

RacerX

[hang_510]

find an external thermometer and verify what temp its at during N.O.T. and compare the gauge to that.

=1/2asssed calibration :lol: but at least youll know the temp for sure.

mine reads low but i know where 180* is on the stock gauge.

[moparvwfreak]

i know the timing is off but i cant adjust it anymore. its retarded as much as possible to get it close to what it SHOULD be timed at.

 

Maybe ck this out first????????? if the dizzy is clocked all the way to one side then maybe the faster you go it the dizzy goes out of adjustment/timming.

 

put motor on TDC ,see if the oilpump dist shaft is at the 11.28 position. If yes then install the dizzy and make sure the rotor points on a plug wire pretty much right ON.

 

also there is a 8mm bolt that hold the timming plate to the dizzy and you can move it more adv or retard so you can cent er it better.

 

Im sure the valves adj isnt the real proplem but might help. I adj mine to .006 intak and .oo8 cold.

 

 

PS anti freeze gives it a higher boiling over temp and prevents cavitation or for us ruining the Front cover/corrosion. USE it but straight water cool better I believe.

 

time motor first, buy a 160deg 54mm stat(generic) then buy a New rad. as they are still cheap for a 620

 

timing is my #1 thing to deal with. as soon as it dries up around here, hopefully tomorrow, i can get back to work on this thing. as for the radiator i had a hell of a time even finding one that i didn't have to modify to fit. i have the small 620 rad (19.75 inch mount to mount) that no one carries. i would rather not modify if i don't have to. plus this one seems to work good. i was just curious as i have not had this happen before with the temp gauge. i got my answer on that. so i am not worried about that one anymore.

[moparvwfreak]

ok i drove ti again today and its getting harder to start. i am REALLY thinking i need to rebuild the carb, thank god for a spare, and adjust the timing. IF when i put the #1 cyl to TDC and teh dizzy drive shaft is not where its supposed to be i have to drop the oil pump to adjust that correct?

 

just want to make sure i have all my ducks in a row before i screw somthing up. also i found another small leak in the rad yesterday that i am gonna JBWeld up like the other leak i had. its small one drop is all i found so its jsut a pinhole. nothing i cant take care of. temp stayed between 1/2 and 3/4 WITHOUT the heat on so i am now alot more comfortable knowing thats about where it should run.

[datzenmike]

When at TDC open the oil fill hole on the valve cover and check that the #1 cam lobes are at approximately 10 and 2 o'clock or in the upward direction. This indicates that the valves are closed.

[moparvwfreak]

i am gonna be yanking the VC off to readjust my exhaust valves. so that wont be an issue :D thats tomorrows project if the weatehr is decent.

[zed]

Datzenmike,

you're right! but what about this:

 

SAE 880266

 

PERFORMANCE PROPERTIES OF COOLANTS

 

WATER 50% GLYCOL 70% GLYCOL

INCREASE IN CYL baseline +45F +65F

HEAD TEMP.

 

INCREASE IN OCTANE baseline +3.5 +5

(ron) REQUIREMENT

 

CHANGE IN SPARK baseline -5.2deg -7.5deg

TIMING FOR TRACE

KNOCK

[racerx]

you got to make sure your oil pump shaft is at 11.25 or 11.28 position. I said both because people here say 11.28 and I saw an ol datsun book that say 11.25. Your cam lobes up fron should be at 10 and 2 ocklock position. You can get close to this by inserting toilet paper in number one and when you are or at TDC the toilet paper will pop out. You can also have someone stick a screw driver at number 1 hole and will feel the screwdriver come up when you get close to TDC. Use a socket, dang forgot the size, maybe 19 mm, I oculd be wrong to turn the crank. The best way to adjust your valves is hot, i am hearing. It is more closer to spec than cold.

 

The external thermometer you can buy in the Kitchen section of any supermarket. I use the one with a big face on it...as far as radiator water we are supposed to use purified water due to core, similar to your iron or any other heating device that has a core. I used to think faucet was good till I talked to several guys who does radiators for a living. Faucet water has hard water and creates build up.

 

You should also install a temp. gauge and while you are at it consider oil gauge and volt gauge. Our cars only had idiot lights....I make it a habit when I buy ol skool cars to install these things.

 

Oh yeh, before I forget...prior to adjusting you valves again, it is best to grind your open ended wrenches the 14 mm and 17 mm. and the shorties work better so that it does not hit other parts of the car when you adjust. I say to grind the 14mm since when you adjust they 2 nuts tend to touch one another and imagine you holding the 17 and while trying to adjust the 14mm...

It makes a whole world of difference

[hang_510]

...as far as radiator water we are supposed to use purified water

I used to think faucet was good till I talked to several guys who does radiators for a living. Faucet water has hard water and creates build up.

deionized is the stuff, purified has the contaminants removed but not the minerals (cations)

 

... when you adjust the 2 nuts tend to touch one another and imagine you holding ...

:thumbup:

IIRC snap-on has the thin wrenchs.

they are worth it! whether you make them yourself or purchase.

[moparvwfreak]

you got to make sure your oil pump shaft is at 11.25 or 11.28 position. I said both because people here say 11.28 and I saw an ol datsun book that say 11.25. Your cam lobes up fron should be at 10 and 2 ocklock position. You can get close to this by inserting toilet paper in number one and when you are or at TDC the toilet paper will pop out. You can also have someone stick a screw driver at number 1 hole and will feel the screwdriver come up when you get close to TDC. Use a socket, dang forgot the size, maybe 19 mm, I oculd be wrong to turn the crank. The best way to adjust your valves is hot, i am hearing. It is more closer to spec than cold.

 

already done. had the dizzy out tuesday night and the pump shaft was right on the money. and iu used the screwdriver meathod to check for TDC. a thin one worked for me as it didn't bind near the top as bad as a bigger one.

 

The external thermometer you can buy in the Kitchen section of any supermarket. I use the one with a big face on it...as far as radiator water we are supposed to use purified water due to core, similar to your iron or any other heating device that has a core. I used to think faucet was good till I talked to several guys who does radiators for a living. Faucet water has hard water and creates build up.

 

i have a multi meter with a temp sensor. and yes it works beautifully. i also know aobut the tap water. i need to pick up some purified (distilled) water and keep it around for doing coolat stuff.

 

You should also install a temp. gauge and while you are at it consider oil gauge and volt gauge. Our cars only had idiot lights....I make it a habit when I buy ol skool cars to install these things.

 

as soon as i can aford it i will be putting guages in. i would like to be able to monitor my oil pressure and voltage. the temp gauge works fine as its has a new sensor.

 

Oh yeh, before I forget...prior to adjusting you valves again, it is best to grind your open ended wrenches the 14 mm and 17 mm. and the shorties work better so that it does not hit other parts of the car when you adjust. I say to grind the 14mm since when you adjust they 2 nuts tend to touch one another and imagine you holding the 17 and while trying to adjust the 14mm...

It makes a whole world of difference

 

i have both good and cheap wrenches. my cheap ones are thinner than my others so i use those. Made in China FTW! at least for that.:lol:

[moparvwfreak]

Driving it now I think the mechanical advance is working overtime. It doesn't want to return to a lower idle. Yet if I let the clutch out a bit and let it bog it drops sometimes. Damn I need a matchbox dizzy. I hate points and since I think my dizzy may be fubared anyway it would be prudent to replace it with a proper EI dizzy.

[lynchfourtwenty]

as for the radiator i had a hell of a time even finding one that i didn't have to modify to fit. i have the small 620 rad (19.75 inch mount to mount) that no one carries. i would rather not modify if i don't have to. plus this one seems to work good.

 

just so you know, i got a brand spankin new 3 core radiator for a 80 720 (which is still l20b powered i believe??) from a radiator shop, anyways it was only $180 it was pretty much identical to my stock radiator but a little thicker, since i've had it i havent had any over heating issues, oh an i run a 180 thermostat while drivin the truck is usualy around 160 but while idling in a drive through or something it sits at like 175-180

[moparvwfreak]

yeah i have heard a 720 rad will fit but requires modding to fit properly. i can get a 74+ 620 rad for about $150 almost everywhere but tis still to big. by an inch. i have been toying with the idea of a rabbit radiator but i ahvent found one thats good and they run about the same as a later 620 one. plus as it sits i think my rad questions have been answered pretty much. plus with some fine tuning i think i can get the temps to drop a little more as well.

[lynchfourtwenty]

whats the difference between the 73 620 an the 74+ 620's? my 77 took the radiator just fine with no modding