Just wondering

[Datsun720longbed]

Ok so I went up a mountain this weekend and I had just rebuilt my l20b but the engine temp reached 210 it normally runs at 175 did I damage anything?

[datzenmike]

No. But in future if climbing mountains check you are filled up on coolant and oil. I've climbed for 15 min straight in third gear at 4,000 RPMs and pedal flat to the floor. Gauge never moved over one needle width. 

 

Check your clutch fan. Engine off try spinning the blades with one finger. If they spin easily or continue spinning when you remove your finger the clutch fluid has leaked out. If working properly you have to push quite firmly to get it to move.

[racerx]

Any coolant leaks? What's your stat, 160, 180? Rad full of coolant?

[banzai510(hainz)]

maybe running lean cause high alttitude or since its a new motor its stilll on the tight side

[Stoffregen Motorsports]

In all the 510's I've ever owned (even my 210hp long rod 2200), the only cooling system upgrades I've done is a thicker 3 row radiator. I always used the stock plastic fan and stock thermostat and sometimes a stock fan shroud. I never had any overheating problems, in traffic or climbing mountains.

 

210 is not overheating, but it is a tad on the high side. 230 is boiling, but there's a basic rule in the engine world: if it ran hot with coolant in the system, then there's not much worry of damage. If it ran hot and the coolant level was low, that may be a problem. Of course this is on a very short term basis. If it always runs hot, then damage may occur, even with coolant in the system.

 

Check your jetting and ignition timing. Pull a spark plug after one of those long climbing sessions and see what it looks like (it's called a plug cut, where you run it in the harshest range and then kill the motor, coast to a stop, remove a plug and check it). Check the color of the cone and, using a magnifying glass, look for teeny balls of metal on the plug cone. If the cone is white or very, very light brown, it may be running lean. If there are teeny balls of molten metal on the cone, then it's probably detonating from too much ignition timing.

[DHale_510]

L motors like rather high temperatures, or at least what looks high. Maybe it's because the aluminum heads and temperature sensor location have much better heat conduction that the iron Fords of old. Also, 40 year old gauges and sensors are not exactly accurate and reliable.

Most L motors today have too fast advance curves. This will cause higher temps and even preigntion. I have found that preignition or knock on my L20b first occurred at about 4500rpm, way above where I could hear it. This was found on a dyno with a sensor. The ideal curve turned out to be wider and slower than any factory combination so I had to engineer a special setup. My racer L18 with crazy compression and electronic crank fire was even more radical but it tuned nicely with the electronics instead of with mechanical springs and things. 

I think the L motors were designed for higher octane fuel and have rather high compressions, especially after a "rebuild" with a shaved head or flat top Z car piston upgrades.

Dennis

[Stoffregen Motorsports]

Holy cow. Is it you Dennis? Been a long time.