If it gets hot at slow speeds it more then likely air flow. See how far you can throw that pice a #*%& flex fan and get a good 4 blade and put a shroud on it. end of problem.
Dr J is right on the money with his advice about running the vacuum advance to full-time vacuum - IE: manifold vacuum. If you'll refer to a Motors Manual and make note of how much timing comes in at a particular vacuum level you'll see they are referring to manifold vacuum. Swap the vacuum advance hose to manifold vacuum and if everything else is as it should be the overheating in traffic will stop. My 462" Buick powered roadster - Walker 4 core radiator and 17" diameter 6 blade stainless flex fan - will idle through a hot summers day traffic and 205 has been about as hot as it ever got and most times it's under 200. 180 degree stat, 8 degrees initial timing, 24 degrees all-in on the centrifugal (Buicks like about 32 degrees max) and a little over 40 degrees at idle with the vacuum advance all-in. (I have run the stainless 5 blade flex fan, also 17" diameter and it works well. They're an excellent fan and pull a lot of air. Both fans mentioned are wide blade models which, far as I know is how they all come.) There's a lot of misconstruments about timing out there, but the good doctor has spoken the truth....
Definitely vac advance to manifold on a Chevy. Happy combination. For those with GM HEI, practically all stock vac cans are for cars with EGR--these have WAY too much advance for use without EGR or with a defective EGR. This rig will ping constantly at part throttle, forcing you to either back off or step on the gas to control the pinging. Look on the bracket attached to the can--the advance amount is stamped there, and most will be in the 20's. At the junkyard, get a can from a truck that's 3/4 ton or up, and check its bracket. It'll be much more reasonable for early engines.
If a flex fan blade get's bent it stands a good chance of breaking at higher RPM. If someone tries to pull the engine over by pulling a fan blade, even once, it can bend it or loosen the rivets holding it together (If it has that type of construction.) "Mine has never had that done" you say, that may be true unless you bought it at the swap meet and then you dont know it's history at all. Or someone might have got it out of the box at the store and played frisbee with it, you just don't know. If you run one DEFINITELY run a shroud, not just to duct the air but more important to act as a ****ter shield so you or your hood don't get cut up when it lets go on the street or worse, while you're bent over it tuning it. Wife asked me why I didn't have a fan on my truck, the engine was running and it was painted black. It now has the tips of the blades painted with some yellow Krylon...
It's all about air-flow "Into-the-Radiator", not around it. Also, running a 195 degree thermostat allows for the water to be cooled longer. Hell, back in the early '70's AMC's had a 205 degree thermostat. I suggest fan shrouds if at all possible, and as for flex-fans, there are good ones and bad ones. You can't go wrong with a Factory Designed unit, they spent a $1M bucks to figure out what their car needed to operate successfully with "Cecil-B-Citizen" behind the wheel.
Alright, it's time for a confession. Confessions of a Hamber - if you will. The Balancer on this motor was a freebie from a friend and though it seems to be doing its job, I can't use a timing light on it. I located TDC with a positive piston stop like C9 detailed in one of his posts, but the motor will BARELY run if I time it using the light to set it to O deg. as indicated by the tab. Up until now I've used the old ear trick & essentially spun that dist. until it sounded like a motor should. Tweaked it down and reved it. Stil sounding good. Take it out and run it. Still OK. It really sounds and responds well, so I can't be that far off the mark, but I sure would like to be scientifically ***ured that it's set properly. So...I guess the message is that backyard mechanical theory isn't the best kind. I've checked some of DrJ's old posts on total timing and I'd like to do that. Given my cir***stances I am at a loss on where to begin. What to do? -r
[ QUOTE ] Definitely vac advance to manifold on a Chevy. Happy combination. For those with GM HEI, practically all stock vac cans are for cars with EGR--these have WAY too much advance for use without EGR or with a defective EGR. This rig will ping constantly at part throttle, forcing you to either back off or step on the gas to control the pinging. Look on the bracket attached to the can--the advance amount is stamped there, and most will be in the 20's. At the junkyard, get a can from a truck that's 3/4 ton or up, and check its bracket. It'll be much more reasonable for early engines. [/ QUOTE ] Yep, that's the situation on a lot of them today, and even the good parts stores don't know which part numbers are the "good ones" You can tell which one you want visually by how far the pull rod can travel in the slot before it stops. The "smog" ones will travel .250"-.290" and that will move 20º-25º at the dampener, too much. You want one that only moves around 12º± so the rod should only travel about 1/8"±. If you have one that moves too far put a short piece of tubing over the bent up part of the shaft small enough to fit in the slot and that should restrict it's travel. (The so called "adjustable" ones I don't think restrict the total travel, just how much vacuum it takes to move it, so that's not the answer.)
You don't want to time the car to run at 0 deg. If you are doing it at idle you want it at like 10deg BTDC.
You can buy timing tape. Find 0deg TDC and put the tape on. That will give you a new line will all the marks you need for total timing.
I've had 1 flex fan shed a blade. I won't have another one. I'd like to see a tech post on va***e advance and timing for popular engines by some of you mechanics out there. Things like what the difference is between ported and manifold va***e for starters and reccommended advance for idle and all in on the SBC, BBC, Nailhead, Flatty, and maybe Olds, SBF and Hemi. We don't seem to get into the basic engine stuff on here and that's a shame. Even things like how to adjust your lifters and pump up the oil before that first fire up could save the newer guys headaches and aggravation on that brand new engine in their project. Stuff like that should really be in the tech part of the board for reference. I'm sure there are those on here who've never used a timing light because they didn't know how.
Tuning (usually speeding up) stock advance curves, changing static/centrifugal advance relationship, and experimenting with the vac can is a real group of speed secrets for a sockish driver. This kind of tinkering usually is absolutely dirt cheap (a spring kit) and produces results you can really feel. I'm not an expert, but the basic formula I use on SBC and late inline Chevies is about so: More static advance, less centrifugal if needed to get total of around 35-37 degrees. Pre HEI vac can to manifold. Lightest springs from dime store recurve kit. Big increase in punch on a smogger.
Flex fans can kill, what if I had my head under the hood tuning? This fan broke at under 5000 RPM........OLDBEET
[ QUOTE ] Flex fans can kill, what if I had my head under the hood tuning? This fan broke at under 5000 RPM........OLDBEET [/ QUOTE ] I rest my case...
I used to race a Desert truck I tried everything to keep it cool two 18" fans, water wetter, high perf water pumps EVERYTHING. anyway after all that went to a old radaitor guy he noticed about a 1/2 gap around the radaitor we sealed this my cooling problem went away as if it was magic air will actually travel around the radaitor. I didnt belive this either but it worked for me. Hope this helps
DrJ, that blade also cut OFF the upper hose (brand new) including the SS wire inside. Everything under the hood was NEW. Happened 10 years ago, took that pic 10 minutes ago, No, I'll never fix that hood, maybe it will keep somebody safe some day..............OLDBEET
It sounds like your listening to to many people to me. Just put the frigin 160 thermostat in it. My car ran the same way and I just changed the thermostat to a 160 and now it runs 180-190. Oh yea your radiator isn't clogged up is it? Maybe the block has a plugged up spot in it. Have you tried flushing the complete system with a real strong cleaner? I've never had my timing make that damn big of a difference in cooling the engine its always been something else wrong somewhere else instead of the timing. And you distributor is supposed to be hooked to a ported va*** from the factory on a chevy. Because if it isn't the advance is advanced all the time when the engine is running so whats the point in having it in there to advance the engine as you accelerate which is what the factory designed it to do. But thats just my two cents.
[ QUOTE ] ...And you distributor is supposed to be hooked to a ported va*** from the factory on a chevy... [/ QUOTE ] Which Chevy? Which model, year, and engine and carburetor? Show me the specs. (Some carbs have a dual source vacuum ports with one being manifold and another in the venturi. Ford I-6s for instance, but they don't have any mechanical advance in the dissy.) [ QUOTE ] ...Because if it isn't the advance is advanced all the time when the engine is running so whats the point in having it in there to advance the engine as you accelerate which is what the factory designed it to do. But thats just my two cents. [/ QUOTE ] The vacuum is supposed to be advanced all the way when the engine isn't under a heavy load for fuel efficiency and drivability, including not overheating. The vacuum advance is supposed to retard under load to keep it from pinging and the mechanical advance is designed to advance with higher RPM. If your tuneup specs say to disconnect and plug the port for the vacuum advance before setting timingwith a timing light then it's got, or should have manifold vacuum, otherwise you wouldn't have to do that! Also, If you have a 160º thermostat you should run at 161º. I have a 180º thermostat and it runs at 181º on the guage, and it creeps up to 195º when pulling hills, when the manifold vacuum is low under load and therefore it's less advanced than it would be on a flat road. I run with 38º-40º mechanical advance at 3000 RPM with an additional 12º of vacuum advance for a total of 50º to 52º advance rolling down the road (at a 80 mph "cruising speed") on regular gas. No pinging, no overheating. 1948 Chevy truck radiator. Stock thermoclutched fan's 2" from the unshrouded radiator. No "waterwetters"
[ QUOTE ] Just put the frigin 160 thermostat in it. My car ran the same way and I just changed the thermostat to a 160 and now it runs 180-190. [/ QUOTE ] Think about it ........... If the thermostat is a 160......and you are running 180-190.......you have no thermostat. It is OPEN all the time after it opens up and the coolant is going from the block to the radiator and back without stopping.
[ QUOTE ] most all chevy's are ported. check this out: www.cl***icchevytrucks.20m.com/vacuum.htm [/ QUOTE ] Not sure what you're calling "ported" but that article is explaining the vacuum advance using the advantages of Manifold vacuum. (Ported usually refers to some source of above throttle plate, and/or venturi vacuum source. If that's what you mean, that article doesn't back it up.)
see if your mom has a candy thermometer,warm up the car with the rad cap off,then wait for the thermostat to open up.
I read the Cl***ic Trucks article and disagree with a couple of items. The comment about burn rates being the same no matter what doesn't ring true. Rich or lean mixtures burn at different rates. The comment about rpm changing the vacuum advance setting isn't quite right. Add a small amount of throttle to bring the rpm's up and the vacuum levels stay about the same. You guys who are running ported or timed vacuum are fooling yourselves. Here's why: Centrifugal advance - as rpm comes up timing is advanced due to centrifugal action on the weights. Vacuum advance - as rpm comes up timing is advanced due to additional vacuum being applied as a function of the venturi effect within the carburetor - which is where ported/timed vacuum comes from. So you're ending up with a double dose of timing advance. More than likely this overly high amount of advance has been compensated for by tuning the ping out or other methods. Once it's been compensated for, most times by retarding initial advance you're left with not enough advance at low to medium engine rpms as you accelerate and not enough advance = not as much power as the engine is capable of making. Reason being, the lower air flow through the carb venturi has the vacuum too low to add the proper amount of advance. If you think of vacuum advance - where GM engines are concerned - as vacuum retard it will be easier to understand. There's more to it and instead of highjacking this post I'm gonna dig out an old article and re-post it. ***le will be, "Got Time."
This is important stuff for rodders to know--altering stock advance curves is the best bang for the buck out there on sixties and seventies engines.
[ QUOTE ] [ QUOTE ] most all chevy's are ported. check this out: www.cl***icchevytrucks.20m.com/vacuum.htm [/ QUOTE ] Not sure what you're calling "ported" but that article is explaining the vacuum advance using the advantages of Manifold vacuum. (Ported usually refers to some source of above throttle plate, and/or venturi vacuum source. If that's what you mean, that article doesn't back it up.) [/ QUOTE ] sorry, it was to separate things. 1 being the article i came across (not supporting my comment, i just ran across it) and 2 being the ported stament. most chevrolets are ported (port above the plates). '58- '61, '70-'75 (these are the years i remember working on), i just looked at my '58 shop manual also.
[ QUOTE ] ... sorry, it was to separate things. 1 being the article i came across (not supporting my comment, i just ran across it) and 2 being the ported stament. most chevrolets are ported (port above the plates). '58- '61, '70-'75 (these are the years i remember working on), i just looked at my '58 shop manual also. [/ QUOTE ] I'm curious what shop manual that is. All have that far back is several Motors repair manuals and the '60 copy states "*On 1958-60 models, which have vacuum advance tube connected to intake manifold thus producing full advance at idle speed, be sure to disconnect tube when setting ignition timing." (page 420 at top of page just under "TUNE UP SPECIFICATIONS") PS. My '74 MGB GT runs Manifold vacuum advance too, not surprisingly...
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