my 401 was overheating. at the time the radiator cap had, i believe, 13 lb cap. so then i flushed both block and radiator and corrected timing. all was well. we checked the water with a dye test and it turned it somewhat blue-green after quite a long time, 10-15 min idling with cap off and did not over heat! the radiator shop told me to put i thought, a 6 lb cap on it so i got a 10 lb. i realize i mis heard him, because with the 10 lb it overheated fairly easily. I have a 16 back on there now, and it doesnt turn on the Hot light anymore, but it is running at temp of about 205 on top of the radiator, 180 on top of the water neck (with a 180* stat). but the heads above the exhaust manifolds run about 215 on the pass. side and about 225 on the drivers. the exhaust manifold is up over 400. so i am wondering if this is normal. also another issue, when this motor was getting hot and blowing the coolant out, it also started puking tranny fluid out the front seal! since i put the 16lb cap on and it hasn't overheated, it hasn't dripped a drop of tranny fluid either. is it possible the lower radiator caps are to blame for all this overheating? my timing is at 3, and i have no a/c with a 7 blade fan now instead of the stock 4 blade, still no shroud. thanks. i have ordered a gauge for future reference. i have only driven this thing a couple times with the new cap, just wondering what will happen. i also ran out of gas when my gauge send just under the 1/4 full mark. is that normal too? it was an n.o.s. piece.
Shroud? =no...loss of 1/2 efficiency Clutch fan? modern replacements start working at 200* vs 170* on the original and if all those extra blades are not turning they actually block the air flow. Pressure cap has no effect on temperature...it just raises the boiling point of the coolant 3* for each lb of pressure.
how can you say no effect on temp and then say it raises the temp 3 degrees/lb? if i am blowing water out at the lower pressure, then keeping it in will let it get hotter. seems like then it will get even hotter, but at least if the water is staying inside the engine it will be less prone to overheating. or am i missing something. what i was thinking was the lower pressure let the water out, which in turn caused the overheating. higher pressure cap, keeping water in, so gets hotter but not enough to blow out. maybe i be missin something?
Raising boiling point, not temp. The answer to the original question pertaining to cylinder temp isn't going to directly solve your problem, you are only seeing the symptoms. I'd use the temp gun to verify changes made, such as what's in the above comments. Timing has a huge impact on temps. The spec would only pertain to the original configuration of the engine, and after verifying the dampner.
well with a 2bbl carb i would think the damper is fine, but havent checked my tdc yet. nor the vacuum advance. what is correct timing with advance kicked in? and how to check too? sorry, not something i'm used to, just disconnect the vac line?
What does a 2bbl carb have to do with verifying the mark on a dampner? You'll have to google some basic tune up procedures and specs.
A lean fuel mixture can increase head temperature. A clogged fuel filter can cause a mixture to be lean. I don't know if that's your problem. But, learned that the hard way. You need a fan shroud, that'll help.
Not sure where on the head you are aiming the gun but both oil and exhaust can run hotter than 180*. [Although at idle, the oil wouldn't] A lean mixture is not likely to cause coolant spewing all over the place. Also seems like the heat exchanger in your rad. is compromised under pressure. I'd be concerned about the rad.
re: damper, i would think a 2bbl means grandma car so not hotrodded, to me, means less chance of damper starting to come apart. am i wrong? dont know. not trying to see a cause of overheating beyond the affect of the radiator cap, cause i know they are legion. the flow across my radiator top is quite fast. good movement. radiator shop guy said he thought it looked great. he did put in his black dust he swears by for stopping leaks. i drained it, flushed it and the block very well when i first got it, after i un-retarded the timing, which was way off. it stopped almost all of the overheating even with the 10lb cap that was on it. the last time it overheated i'm thinking it had blown coolant w/o me noticing it while i drove it four or five times around town, so that that is what was mostly to blame when i took it out on the freeway at 65-70 and it then overheated. once i got off and drove slowly about 35-40 the red light went out. but it was really out of water then too. i was thinking head gasket. now i'm thinking maybe just the cap being too low. i have driven it 60 for five miles and i got the temps with the gun in the first post. i just been afraid to duplicate that bad run. but i am making sure i am topped off with both water and trans fluid before i go. i havent lost a drop of trans fluid since, as i have not overheated again either. haven't driven it that far or hard, but guess trail by fire is the only option left to be sure.
I thought that's what you meant about the dampner. It's old enough to have been replaced along the way or the rubber deteriorated. I don't recall off-hand if the nailhead piece can slip, but... You have an overheat problem. I would assume nothing and methodically eliminate things step by step.
On a nailhead the damper ring can slip....:Brow: overheating is usually caused by poor coolant circulation.... the things that need to be checked are radiator circulation,,, the amount of air coming thru the rad.... the ignition timing.... also check inside the dist cap at the plate/vac advance rubber bushing to see if it has rotted and crumbled apart allowing the advance to over advance,,, also check the vacuum holding ability of the vacuum advance.... both are critical,,, also critical is the timing mark position,,, I have seen them mis marked at the factory... A fan shroud is a absolute must.... so is a 7 blade fan.... but your temps readings seem about normal... the trick is keeping them normal...:Brow:
Next time you get your IR gun out check the temperature of the top tank and then the bottom tank (or thermostat housing and water pump where the lower hose attaches)...engine hot and running fast idle: report back.
ok so i put a S-W mech. temp gauge in and i'm running at 220. so is that normal? i read that the hot light comes on at 218, which it did. i ran 60mph, was pretty steady at about 200, went to 70 and temp went to 218 pretty quick. that was the first ride, the next one i kept it at 60 and the same thing, just slower, all within about 4 miles on the highway tho. when i cruised for a mile or two at 40 it didn't drop. btw i now have a 16lb cap on it too. i have NO LEAKS anywhere. i checked the vac advance and it goes way up to about 15 or something guessing cause no marks there). and at idle it's just 3, or whatever that last timing mark is at. checked the Dwell, it's only at 25, factory calls for 30 but it was at 20 and i was able to raise it to 25 but my allen wrench wouldn't go in anymore to try and get it up to 30. my first ride above, was with the Dwell at 20, second one at 25. i am wondering if i need to change the head gasket, and get the heads milled. so ok, now this is an overheating post. also, my ir gun said the same as my temp gauge but only when it was pointed at the blue gasket sealer. lower at both the top of the radiator and the bottom, much lower at the bottom. it is working.
Before you expend any more effort and money on that puppy,,, get a compression gage and run a good test of all 8 cyls.... that result will tell you if the engine can be tuned to run correctly.... and if you have a popped head gasket or cracks some where.... a lot of times on vintage engines , they have ''sandwitch'' type head gaskets and they rot... allowing compression leakage....
Is the radiator cooling adequately? This ain't like a computer where "I want to skip this step and try something else"...not optional:grin:.
radiator not leaking, flow is fast and furious at top so assuming no leaks. no steam, no drippage. good temp drop...Huge! from top to bottom of radiator. what good would advancing timing do if factory specs are 3 degrees? i'm listening. if anybody else thinks i should give this a try i might. stock dizzy and coil. looks original except for cap. i have not put new points in it tho. has a new cap i did not put on. can't see that mattering as far as temp goes. did compression test too way back last summer. about 165 across the board but the last one read like 180. did it again same thing. did it a third time, 165. i dont have an explanation. just checked the coolant level after my last outing and the radiator is still full. b'ham bulldog, assuming you live in b'ham, i'm in mt vernon. great place to live until the nut jobs from oak harbor show up and decide to kill us.
The biggest thing is modern gas is nothing like the gas your engine was originally designed to run. If you're running retarded and rich it will heat up. Advance the timing, lean out the mixture as much as possible. Bump up the pressure on the cap if necessary, maybe go 15 and yes, run a 195 T-stat. Uniform heat under pressure should keep it under control. When I dropped in a modern aluminum rad in my dead-stock Wildcat the overheating problem stopped; - there is something to be said about modern rads and their improved heat dissipation characteristics.
First, we are talking about a car and engine that is 50+ years old. How likely is it that the distributor that is installed in the engine is the same one it left the factory with? Nailhead distributors differed in the amount of mechanical advance built into them depending on the year of the engine and other options. If the distributor is different, then the original initial timing spec becomes irrelevant, it no longer applies. An engine does not run at the initial setting, except at idle. As soon as you step on the gas and RPM increases, the mechanical advance adds timing. In addition, the vacuum advance on early engines was connected to manifold vacuum, so it boosted timing at idle. Retarded timing causes an engine to run hot. More of the heat of combustion goes into the cooling system instead of being used to drive the piston down. If the engine is running at a constant 3*, that alone would cause it to run hot. You need to check both the mechanical advance and the vacuum advance and make sure they are working. Full throttle timing (initial + mechanical) should be 30-34*, Cruise timing (initial + mechanical + vacuum ) should be 40* or so. Check and adjust dwell before looking at ignition timing. Changing dwell changes timing. Changing timing does not change dwell.
That could be it! The '63 LeSabre 401 with Dynaflow automatic trans is spec'd at 12* BTDC. The later 64-up with ST400 automatic is spec'd at 2.5* BTDC. Original '63 distributor should be #1110962. Number is stamped on an aluminum strip wrapped around the base of the carb. Vacuum advance 'can' should give 10 degrees distributor advance at 14" of vacuum (or 20* at the crank). They will not operate properly once the rubber diaphragm starts to leak. Should provide 20* mech advance at the crank at 3600+ rpm. Full advance, (initial + mechanical, no vacuum advance) should be around 32*. If you set the correct '63 distributor at 3* initial, you'll be around 23* total (no vacuum advance) and are giving up some power!
