Ok, Here is my situation. Just running the engine in the garage for 10 min and it overheats, straight up to 250* with the fans going full tilt. If it is cool weather I can drive it around a little bit, but if I get stuck at a light the temp skyrockets. My setup is as follows: I have a built 455 with a Demon 1000 carb, MSD Electronic ignition and distributor (electronic advance no plugged vacuum lines here). It has a new Aluminum radiator and an electronic dual fan with a thermostatic switch (the fan comes on just fine). The fan is made for a motorhome application. It has TA headers (jet hot coated) so the engine compartment gets pretty hot anyway. Ever since i've had the engine it has run hot, very hot, and I have done all I can do to fix it without some help. Ive tried taking out the thermostat and running it without the thermostat - no change. :blast: I've tried getting a new radiator (hence the new aluminum radiator) (bought a griffin 19X31) It used to have a good normal 4 core radiator. :af: I've checked the advance - 14* at idle, all in by 2200 at about 34*. I have put the temp probe off of my multimeter into the upper radiator hose to verify that my temp guage is working properly. They differ by a little bit but, it still shows excessive temperatures. I have put in 85% water 15% antifreeze and a bottle of water wetter, helps but doesn't fix the issue. It has a new radiator cap that holds pressure just fine until it gets up to about 260*-270* and it starts to boil over. There are no underdrive pulleys on the water pump. normal factory pulleys. The belt is just fine... Searching this BB the possible other issues seem to be: Too lean fuel - I have NO IDEA how to do anything with that carb (demon 1000) except change the idle speed. any tips? I didn't get any literature on the carb from my engine builder, so I am very much in the dark?? Water pump failure or insufficient waterpump operation to push that much water? : I'm almost to the point of just replacing the waterpump. How can I reasonably test the waterpump? Are there good electric waterpumps that I could use that might pump a larger volume of water. Airlock. I've filled and refilled the radiator numerous times, including letting the engine run with the cap off to fill, and running with no thermostat. seems unlikely that there would be a major air lock but i'll take suggestions?? Heater core issues. Is it possible that the heater core lines could somehow be causing problems if they were installed improperly or ??. I'm reaching here... Radiator issues? Is it possible that the flow is screwed up on the radiator. It is a new griffin 19X31 with the input side top drivers and the outlet on the lower passenger. It is a side flow with the resevoir tanks on the sides. Help me please, i just can't figure this out. With my setup this car should run a cool as a cucumber! o No: I'm afraid it might have a lot to do with the carbeuration which will mean that i'll probably need to enlist professional help. Thanks, Shawn
Man, you have just about covered all the bases. Here's my 2 cent worth: 1. With cap removed, can you see the water circulating through the vanes of the radiator. If not, you could have a pump problem. 2. Does it over heat when the cap is off? 3. I don't think a car would run at all if fuel mixture was that lean. 4. Any chance the manifold, head or gasket passages are blocked from flowing properly? 5. Take the guts out of an old thermostat and install just the outer ring. This provides enough restriction to allow water to cool in radiator while providing maximum flow. Good luck and let us know what you find.
fan, try the proper belt driven fan and shroud, but if you still want the electric fan the one you have is probaly not enough, i have tried electric fans and if they are two small ,it will get hot fast, you have to spend some good money on a decent fan or dual setup and a alternater to keep up with it and most important is you must have the proper fan shroud to draw the air accross the radiator and engine. , there are alot of treads on the subject you can check out. i personaly run the stock 7 blade thurmal clutch fan set up with a 4 row radiator. just my 2 cents
Check for spring in lower rad hose to prevent it from getting sucked closed by water pump. Electric fans spinning the WRONG direction to move air through the rad. You'll never find an electric water pump that pumps as much water as a belt drive mechanical unit if it's in good condition. As long as you're just idling in the garage, try adding another ten-fifteen degrees of advance. If it runs cooler, you need vacuum advance. Basically, if you drive at part throttle, you should have vacuum advance. Better power, better economy. Do you have an H-pipe or X- pipe exhaust system? IF the pipes aren't joined somewhere, check for equal exhaust out of both tailpipes. Maybe you have a restricted exhaust that's forcing exhaust from one bank through the intake crossover to the other side of the engine. If the pipes are joined, you won't be able to tell from the tailpipe pressure whether there's a restriction ahead of the H or X crossover.
Last resort is to check for exhaust gases in your coolant, which would point to a head gasket problem. I agree, electric fans are not the way to go. A belt driven stock 7 blade 18" fan will be more than enough. I have the NAPA 271301 fan clutch which is far superior to the stock Buick unit. It moves alot more air at low speed. The application fits an 85 Chebbie 3/4 ton P/U with a 454. Alot beefier unit, and costs about 100.00
Running NO thermostat is a bad idea - the water circulates too fast through the radiator to allow any heat exchange. Do you have a stock fan shroud and clutch/fan setup ?? I'd swap that back in to see if it changes things Are the electrics set up to pull or push ?? First thing I would try is a new waterpump - see if you can find one on Ebay thats NOS (New Old Stock) ( or maybe CARS or another vendor....alot of times on rebuilts the clearances on the vane are too big. External Trans cooler ?? DONT run the engine much past ~230 deg Also - Whats your temps if you're cruisin' at say 40 mph or better ??
i think you need to look at you electric fan set up. you say you can drive it around but as soon as you stop it gets hot. while your driving you really dont need a fan because of the air flow through the radiator. if it was your water pump or lower hose it would be hot all the time. i got rid of my electric fans for the same reason. to much of a problem.
Alan- That's an old wives tale. There is no such thing as water moving too fast. However you are correct that you need a thermostat, it's just for other reasons. Shawn- Several years ago, I remember reading about different vane designs on water pumps. Some manufacturers used wimpy vane designs and don't work as well. I forget how to get the good ones. One other thing. If you want to test out your radiator, conduct a short experiment- run your car in the driveway, and spray the radiator with a garden hose. Even with a tiny two-core radiator, that should take away an incredible amount of heat from the radiator. If you still overheat, then the radiator isn't your problem. -Bob Cunningham
Has the engine been rebuilt recently? How are you sure that there is no blockage inside the engine? I used to overheat a lot down in Texas after I got my 455 rebuilt and running. I put twin 16" electric fans on it, a big Griffin aluminum radiator, tranny cooler, new waterpump, etc....it would still overheat if I sat for a little while at idle. I finally figured out that one of the fans was blowing air the wrong way (DOH!) and my heater core wasn't getting any flow through it because of a stuck closed valve (for the A/C). I made the fans blow the right way, put a 160 degree Robert Shaw thermostat in it, pulled out the A/C equipment to allow more airflow, and bypassed the stuck valve and I can now idle all day long on only one electric fan....once I get moving I can turn them off totally! If all of your fans and water pump are working properly, and you can't find any water blockage in the system I would think there's something wrong internally inside the engine. Could be a blocked coolant passage in there. Have you tried having the cooling system professionally cleaned/flushed? Don't know what else to tell ya. Good luck!
If you have good compression and the engine is timed right - statically and the centrifugal advance - and if your fans turn out to spin in the proper direction more than likely your problem is lack of vacuum advance. Without it, almost all hot rod type engines as well as the stockers - on GM engines anyway - overheat. Other brands of engines - modified - respond well to typical GM timing curves. I'm with Larry in that I don't think the electric fans do that good a job. In fact, when I built my BBB powered 32 roadster I made a point to set it up so I could use a mechanical fan. No thermostatic clutch cuz there's no room. In fact the front sheave on the lower pulley had to be machined off to allow the fan to sit on the water pump pulley utilizing a spacer about 3/16" thick. Since the Deuce Factory frame came set up for an SBC with a 1" engine setback - which looked to be right at the time - the BBB with T-400 fit in the car ok, but there was no room for a mechanical fan. As things ended up I had to cut out the trans crossmembers and move them back 2" and after the sheave was machined off the fan fit ok. The fan's blades sit about 1/8" in front of the sheave, but it's ok because when the engine starts the fan blades pull forward a bit at idle. The fan is a stainless flex fan, Hayden brand - I've run both the five and six blade fans in 17" diameter and even with the tight fit of the BBB in the small stock length 32 engine bay, the engine runs cool in 100 degree + temps in traffic. Most times 195 degrees and the most I've seen on the accurate S-W mechanical temp gauge was 205 idling through the In & Out Burgers drive-through lane. Reason I point out the fan brand is; the Haydens have the blades offset from center toward the rear. Most other brands of stainless flex fan I see have the blades on center. (When viewed from the top.) If you don't have a shroud for a mechanical fan and there are openings to the sides of the radiator, the air will take the path of least resistance and pull air in from the sides and bottom as well as the top and cooling air doesn't go through the radiator. If you have a stock distributor handy, install it, time the engine to stock specs on the initial and check the total with Centrifugal timing all in, connect the vac advance, check to make sure it's advanced at idle (bout 16 degrees of vac adv if I remember right) and if the other stuff as mentioned above is ok, I'll bet the overheating goes away.
I learned the need for flow restriction in circle track racing. We assumed, as with intake and exhaust, that more is always better. Out the thermostat went, and five hot laps later, thar' she blew. A veteran racer suggested the gutted thermostat, I described above, and that regulated the flow enough that overheating ended. I have used it on my hi-perf cars ever since. BTW, I had read and article somewhere about the problems electric fans have pushing, or pulling, through thick radiators.
Are the fans on a switch or on a thermostat set-up? Most electric fan thermostats are set to 230-240 degrees. Push goes in front Pull goes behind the radiator. Main bearings to tight?
Overheating at idle is an airflow issue, period. I assume that driving around (i.e. lots of airflow) everything is ok? The only electric fans worth getting are the Lincoln Mark VIII (3500+ TRUE cfm, 100+ amps on start, 35+ amps continous), Spal, Derale and the Viper fan. Spal and Derale are the only aftermarket fan manufacturers with truth in their cfm ratings - a good indication is amp draw; anything over roughly 100 cfm per continous amp is pure hype.
I beg to differ. My roadster was connected to ported vacuum in error and overheated in traffic on moderate days. With no other changes than selecting the vacuum advance to manifold vacuum, the idle and in-traffic heating problem completely went away.
Doesn't hooking Vac Adv to Manifold cause the distributor to work opposite of its intende purpose? Floor it and you lose timing due to low manifold vacuum. Hooked to manifold makes only mechanical advance available as vac adv is always in.
No Vacuum advance and mechanical advance operate independently. Your total timing is always a combination of initial+ mechanical+ vacuum. You should always set up your mechanical curve with the vacuum disconnected and plugged. Set it up to get your advance in as quickly as possible, without pinging/detonation. Then add vacuum advance, and check for part throttle ping, and tune that out. An engine can tolerate more spark advance at light loads. It enhances throttle response and gas mileage, and the engine will run cooler. Vacuum advance should be responsive to engine load. You don't want it at high loads(heavy acceleration, and WOT) If you hook it to manifold vacuum, it will add advance at idle which will make the engine run cooler in traffic, and make an automatic transmission car very responsive. When you floor the gas, manifold vacuum drops off, and the vacuum cannister degrees goes away leaving you with your mechanical curve. That is why it is important to optimize your mechanical advance curve. The stock distributors brought in the mechanical curve slowly. You often didn't get full mechanical advance until 4000 or more RPM. As a result, only part of your mechanical advance was in at cruising speeds. The vacuum advance added an additional 14-18 degrees. If you bring all your advance in at 2500 RPM or less, you have to limit the amount of degrees in the cannister, otherwise you will overadvance, and ping. Vacuum advance is icing on the cake. You need to spend a little time tuning and experimenting with your engine. The best way to do this is with the Crane Adjustable vacuum advance kit. It comes with the springs and everything you need to change the amount of degrees available and the rate at which it comes in at. Lots of guys want an instant recipe, a one size fits all. It's not that simple, you need to find out what your engine combo likes. It takes alot of trial and error. That's half the fun though, don't you think?:laugh:
Take a look at the advance specs for the 70 455 Stage 1 distributor. You have an initial timing of 10 degrees BTDC. At 1800 RPM, you have an additional 9-13*, and at 4600 RPM, you have an additional 20-24*. So say your cruising down the road at 60 MPH, at a liesurely 2600 RPM. You have 10 initial, and maybe an additional 18* for a total of 28*. Then the vacuum advance provides another 14-18*, for a total of 42-46* You flat punch it, and manifold vacuum goes close to 0, the vacuum advance degrees go away, and as you climb to 4600 RPM, you are left with 10 initial + an additional 20-24* for a total of 30-34* at WOT. Now that is ported vacuum advance, but you could easily hook the vacuum advance to manifold vacuum, and at idle you would have 10 + 14-18*, for a total of 24-28*. Nothing wrong with that with the stock distributor. Vacuum advance would still drop away under rapid acceleration and WOT, leaving you with the stock mechanical curve peaking at 4600 RPM. Whether you hook your advance to ported or manifold vacuum, they both drop off at WOT. Ported doesn't let you use the advance at idle. It rapidly gives you advance as you open the throttle, then falls off when you go WOT. Manifold is there at idle, and light cruise, and goes away a little quicker as you open the throttle, just like you want it to. It responds to engine load, just like it was designed to do. Now, like I said above, if you bring in the advance quicker than stock, you need to alter things.
I would also look at the electric fans. I had this problem on a 350 one time with elect. fans. I could drive anywhere, until stopping in traffic. Then, the temps would rise quickly. If you see water flowing good inside the radiator, I would think your pump is doing ok. Running without a thermostat may cause a heating problem. Above it was stated as a "wives tale", but I have been told by many mechnics over the years that it causes the water to flow too fast. GM certified techs have verified it to me also. So, I would assume it's a bad ideal.
The biggest problem people have with electric fans is also one of the biggest problems with engine driven fans... Running them unshrouded, I run the Flex-a-lite 295 system, its an all in one molded shroud with rubber seals, dual 13.5" fans, thermostatic control and variable speed controller. On a 90 degree day sitting at a light I might hit 195, if I'm running the a/c. Most of the time it's rock steady at 170 with the fans only kicking on occasionally.
Larry, What you are saying is what I know to be true of vehicles during the carbeurated emission controls era. Prior to about 1975 every vehicle I have had was set up for ported vacuum. All of the Holley carbs I have run have a ported vac outlet on the side of the front metering block and I used it. It goes, without saying, that ultimate performance and predictability can be achieved through mechanical, or better yet, electronic timing controls. I run stock distributors with a combo of vac and mech. timing advance. I install a $5.00 curve kit from the parts store and port my advance and get supurb performance. Had a 78 Buick with a 403 that was set up as you described, from the factory, and I just didn't care for the way it would feel like it was going to launch for the moon, then immediately, fall flat on its face when I punched it. I guess without getting into the whole deal of flame propagation, piston speed at, or near, TDC as the product of rod lenght to stroke ratio, and Volumetric Efficiency as it effects manifold pressure, what I am saying is that ported vacuum is what the what us older gearheads are comfortable with. (when Budget is an issue) The quote you exerpted above did not relate one to the other but, rather, stated that the absense of one would leave you with only the effects of the other. I may have missed something in my engine schooling, but I have never heard of anyone running an engine at 46 degrees total advance at part open throttle. What you describe above is what you would have if you were cruising the freeway @ 75 MPH. You run vacuum advance with that MSD unit?
