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My 1971 521


d.p

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Something odd I noticed recently. I was using my old cap from dual points dizzy and since I was having so much trouble with my idle I said fuck it and swapped that cap for the cap (bronze/copper contacts??) crash sent me with the Pertronix.  My idle was still up and down but my engine temp was lower than it ever was before which was odd.  Usually my temp gauge was right around the break if not on it and after swapping caps its sits just to the right of the cold line. 

 

I also warrantied my carb from webercarbsdirect sent they me a replacement genuine weber.  At first I just switched the idle jets from the new to the old to see if that helped but it didn't.  So I said fuck it and swapped the old carb out for the new one and right away my idle seemed to even out and I was able to get it to hang right around 750-800RPMS at 12 BTDC.  Changed my fuel filter as well. 

 

Been driving it around town without any issues so hopefully smooth sailing for a little while.  

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Is it possible your thermostat is stuck open?

You should be able to check the temp of the bypass hose coming from the intake and compare it to the upper radiator hose......

The bypass hot should get hot before the upper radiator does....

If it does thermostat is working ...

If they get hot at the same rate thermostat is stuck open....

 

I'm not actually sure if an open thermostat would keep the temp that low or not, or how long it would actually take to warm up.. worth the check to rule it out...

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Generally if you don't have a thermostat or if it is stuck open it will take forever for it to warm up, but that really depends on the vehicle.

If the radiator is on the edge of not being large enough it will warm up quickly like on my 521 turbodiesel, that truck and my work truck warm up to normal operating temperature fast, they have much larger engines than stock, but I still am using the stock 2 core radiator.

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If there is any doubt about the engine temperature replace the thermostat. They don't last for ever and not worth the bother of testing. If you are going to the bother of draining the coolant, removing and getting a new gasket.... cut to the chase and replace it and be done with it. Always get a good $10 one not the $2.99 specials from wallmart.

 

Temps should always be near the half way mark on that 'run range'. Maybe just below half. Engine should warm up in under ten just idling and much faster if you are driving. In the summer my 710 begins to read within a kilometer and reaches warmed up in about three. A failed thermostat that is not closing will be slow to warm up and will not reach the mid point on the gauge. On long down hills out on the highway my L20B with a stuck open one would drop right down to the cold line. Remember your engine is tuned for, and runs most efficiently when it is around 185-195F. The engine heat is what fully evaporates the fuel mixed with the air. Gas will not burn in a liquid state it must evaporate first and mix with the air. This is why a cold engine does not seem as peppy when you floor it.

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always use new gaskets and have spares. Most likely they will rip. They are cheap

54mm is the size of the stat. Most come in 160 180 and 195 deg. depends on what you want to run.  I run a 160.

Fancy $$$ stats are designed if they go bad to OPEN. cheap ones dont

 

But most stats are closed the majority of the time just to let enought water into the rad so it gives it time to cool down. 

 

 

I also put antiseize on the bolts as they seem to rust over time and this helps prevent that. I also do the water pump bolts and tha shank part. prevents rust

 

 

the bronze copper contack  dist cap will last for 5 years or more. As thats how long I been running them. Up to 8 yrs on my daily driver.( BLUE STREAK cap)

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D.p., its not what like its what works. 2 failed stant tsat. Several years ago, my 65 mustang and 510 were overheating. So I changed the tstat and installed a new stant. And still overheat, took it off and did not overheat. I boiled it and supposed to be like 185 degrees, didn't even open. I think I got a beck and arnley. Compared the 2 quality was beck and arnley. Then the mustang was overheating, changed to stant tstat and still overheating. So boiled the new one and stuck a thermometer and supposed to open at 185, guess what it did not open till 205 or so. Put another thermometer in the pot of water and temp. Was confirmed at 205. Changed to another brand and no overheating. Maybe I got a bad run or just maybe made in China crap and quality control issue. And I've used stants before and no issues prior to mustang and datsun.

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I say thats perfect.  but hotter be good for the heater in winter

But I notice on all my datsuns that in summer 85deg + at idle at repeated stop lights my temp goes way past the normal temp line.. till i start moving

 

So thats why I say your OK unless you want a hotter heater otherwise I wouldnt worry about it as you dont drive this often

 

 buy a Nissan STAT if your worried. BUT  I have run the STANT brand

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