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timing vs temperature


capt den
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how much does timing affect the running temp of the engine? if too far advanced why does this have any affect at all, or if too retadred what does that do? seems i should know this by now but it does puzzle me. i cannot get my engine to keep a good temp, especially at idle or in stop/go traffic on very hot days. after doing everything recommended on this site i have finally concluded that there must be more crap in the block that i have not gotten out. it seems to run at the best temp at mid speed[40 to 45 mph] on less congested roads. idle is always bad and high speed gets the temp up. it does not overheat but will get very close to over the normal range. i have checked the temp with a thermometer and it is correct to the guage. without boiling out the block i may be at a dead end. this is the 265.     capt den         

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"What happens if engine timing is too advanced?

Overheating. If ignition timing is too far advanced, it will cause the fuel-and-air mixture to ignite too early in the combustion cycle. This can cause the amount of heat generated by the combustion process to increase and lead to overheating of the engine."

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in your description you state that it does not idle smoothly.  That would be my first point o check out as to why it is not idling smoothly.  Have you made any adjustments to the carb, the idle speed or air mixture screw. Have you done a tuneup on the car. Might also be the condensor, rotor, cap, wires and or plugs.  Run the car in your garage at night time with all the lights out and have the hood open look to see if you see blue streaks comingoff the sparkplug wires. If this is happening then you need to replace the wires they are leaking.  Then look at the cap at the contat points at the top of the cap are they worn r carboned, any grooves inthe contact area. how is the carbon contact that come down from the top of the cap to the rotor, is the roto bad. Check that all of the sparkplug wires are pushed firmly into the cap and onto each plug look for corrosion on the cap where the plug wire connect to the cap and also on each spark plug.  Check the condition of each plug, pull each one look for carbon, clean them and reset the gap.

 

These are just suggections to help you get the car to idle smoothly.

 

Let us know what you find.

 

Rich HArtung

desoto1939@aol.com 

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rich, i meant that at idle it is bad temp wise as the temp goes up fast,right up to the end of the "normal" range bar on the guage. it will stall then too and can be difficult to start. and keith, as far as the heat generated by the combustion process, isn't that the same no matter when it ignites. the book calss for 2 degrees BTDC. would setting it at zero, or even 2 degrees ATDC help, or it would just run worse. anyway, still confused about the timing and overheating, and how far off should it be to really make a difference assuming all other tune up specs are correct. thanks,   capt den

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After you make sure all the tune up items have

been addressed if you're still having problems

check your thermostat. with engine warmed up

look into the radiator & see if coolant is circulating.

Also, has heat distribution tube ever been replaced?

.

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Okay you asked a question, does the timing matter?

Yes it does.

Away back in the 1970s the manufacturers were dropping compression ratios and retarding the timing like crazy.

What they found was that in stop and go traffic the cars were overheating because the timing was too retarded.

Retarding the timing causes the exhaust to still be burning when the exhaust valve opens, which increases the engine temp.

To prevent overheating some cars ran the vacuum signal from the carburetor through a temp valve on the thermostat housing then on to the vacuum advance chamber.

Thus when the engine temperature got to a certain point the valve opened and gave the engine some advance until it cooled down. Savvy mechanics took the valve out of the circuit so the engine had a normally working vacuum advance.

Further some manufacturers made distributors with no advance at all! I replaced a worn out Mazda pickup distributor with a Mallory dual point and it was shocking how much better it ran.

Too much advance is not productive either and can be destructive.

The usual tune instructions are to find a good long hill and make some runs on a hot day. Advance the timing until the engine pings and then back it off 2 degrees and retest. You want it as advanced as you can without pinging. Of course some engines might not ping and then you have to guess. 35 degrees total advance is a good start point.

 

A bad carburetor mixture setting can be compensated with a timing change. The ideal is to have your mixture correct before you play with the timing so you actually reach the optimum fuel/air mixture and the optimum timing and not a compromise. 

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timing retarded sounds more like why it could contribute to heat issues.how much is too much? don't know. i know my timing is set at zero right now, so since i need to put a little more dwell on it, i will set the timing to factory spec of 2 degrees BTDC. had it out today and it ran well with no issues. 65 degree days does help. thanks for all the info. i can always learn something on this site.    capt den

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I assume you are running the factory fan and the radiator has been cleaned?

 

While you are doing your tune up, it may pay to pull a selection of sparkplugs to assess your running mixture. If you are running too lean it can run hotter as well. 

 

I have always had good results running more aggressive timing advance than stock, in both performance and economy. 

Try 2*, but I wouldn't be scared to try 4*.

Or even ignore the timing marks, and advance till best vacuum reading is reached (within reason). Often old timing marks will no longer be accurate.

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There could be a lot of reasons why your car is overheating but I doubt its because of the timing or mixture in my opinion.  I'd keep checking into the cooling system.  You said you've checked all of the things recommended on this site but what are those things? Have you checked the calibration of the thermostat?  Did you remove and replace the water distribution tube?  Is there more crud in the block?  Has the radiator been flushed and rodded out?  Is the rest of the engine original?  How far from the radiator is the fan?  Those are a few that come to mind.

 

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