10° at idle is a really piss-poor number.. and I can absolutely guarantee that your manifold vacuum reading is way lower than it should be. Hook the vacuum advance pots hose to a full manifold vacuum source and watch the vacuum climb up to where it should be. Just be sure to set the idle speed back down and readjust the mixture screws to better suit the now higher manifold vacuum, is all. You should be setting all this up with a timing light AND vacuum gauge too. The higher the vacuum readings.. the better.. but unless you know how to properly recalibrate the carb's fuel curve.. you will eventually reach the point of diminishing returns where the carb's current fuel curve will cause a lean cruise surge or rpm breakup as you push the timing lead more aggressive/closer to what it should be. Even if that improved timing/manifold vacuum number doesn't help your over heating issues.. there is no way in hell that it will hurt it. Low speed and light throttle mileage will surely improve as well.
Maybe so but almost every Ford of the '60s & 70s were setup as such, overheating wasn't a issue... The almost included the '67 289 that had a service bulletin saying to connect vac advance to ported vacuum, as when connected directly to manifold vac the high amount of advance at low RPM was causing front main bearing knock..
And that may very well be true as to why they issued that ancient TSB.. but that means nada from the standpoint that there were surely underlying issues resulting in such an issue to rear its ugly head. It was used purely for damage control.. not because higher base/centrifugal sweep timing maps cause those types of issues. When it comes to old motors.. ever see thrust bearing clearance and wear related problems due to crappy machining and parts tolerances(many times causing a cumulative and combined affect)?.. or even related to torque converter/transmission bearing slop issues? A bit rhetorical.. but for a comparison sake of showing how things have progressed.. also worth asking if they ran 10° on an EFI/ECU based 302 in the later years? I've seen several tuning maps through the years and I can assure you that they did not idle at 10°. The combustion dynamics are just what they are despite some of the more modern chamber designs. Mixture motion and fuel density within the chamber NEED much greater timing lead to adjust peak pressure to the optimum point in the power stroke.. which is why the manifold vacuum goes up when you get it closer to right. EFI primarily helps in the fuel curve control aspects of these engines(any engine really) and generally helps improve cold start issues related to poor homogeneity/cold induction/start efficiency.. but it does almost squat in comparison to a well tuned carb from an overall physics standpoint within the combustion chamber on a warm engine. This is why a well tuned/calibrated carb can still best an EFI setup in overall power delivery. Just takes much longer and more elbow grease to get to what the EFI can do with far less time and effort, is all. IOW, a 1968 Ford 302 can have the old mechanical/vacuum advance controlled distributor tuned to accept and benefit from(higher manifold vacuum and torque production) that is gained with extremely high ignition lead rates at idle/off-idle speeds nearly just the same as one that has the mapping done within the ECU for the engine produced in 1988. The biggest gain with the ECU controlled setup is the ability to run ridiculously high ignition lead numbers at idle and even highway cruise speeds.. well, what some will argue is way higher than it should be.. up into the mid to high 40° range.. and then pull timing out to what the engine prefers for full power at higher loads. That's the beauty of computers.. to go well beyond the mechanical restrictions of these 80 year old ignition systems to allow you to have your cake and eat it too. My old Vortec powered work vans routinely mapped(when set to "self learn" mode) upwards of 48° at light cruise in OD on city streets and my old 383 Chevy was set at 54° up to around 1,700 rpm too. Set it to anything lower and manifold vacuum and cruising efficiency would suffer every single time. The engine just wants what it will tolerate.. not some arbitrary number that was floating around nearly 50 years ago. Also consider that when it comes to idle speeds/off-idle speeds(below the tipping point that the ported source will start to add timing into the equation anyways).. there's a balance to the OEM's reasoning for increasing one kind of emissions(raw fuel going out the pipes) compared to increasing the other much more detrimental emissions that higher base and vacuum assisted timing will add to the mix. NOx. Always a tradeoff in there somewhere. But I figure my little hi-po motors are already ahead of the "total output" NOx curve when compared to a bus or truck or whatever else with a 7+ liter powerplant hauling heavy loads around on a continued basis anyways. I just make damned sure I have no exhaust/cabin leaks out back to poison myself while I'm out having fun. Point is with all this.. 10° at idle isn't squat and your manifold gauge will tell the true tale of how happy the engine really is with it. Adding that extra 15-20 degrees of vac advance supplementation at idle speed by using the full manifold vacuum ported source.. compared to waiting for it to finally come in at a slightly higher rpm from the ported source anyways?.. is just allowing the engine to be more efficient at an earlier time is all. One source is available all the time until the go pedal gets pushed hard..and the other is only available over a narrower rpm range. Again.. based on the physics(already mentioned above) involved within the combustion chamber at extremely low rpm?.. more timing lead is almost always better. And the vacuum gauge will usually reflect that reality. Nuff rambling for now.. not trying to argue.. just pointing out what I and many others who have proven time and time again can benefit an engines AVERAGE power production and overall efficiency. As you well know by now, we drive this stuff on the streets and not everything is based purely on WOT performance. PS.. and to be clear here.. I'm not saying that this amount of insufficient base/vac assisted timing is the root cause here.. only that it will never hurt to have engines tuneup closer to right in the first place. Plus.. I'm a stickler for pointing out easy to fix issues like retarded timing scenarios like this. Maximized timing(resulting in higher manifold vacuum) is potentially some of the easiest power/efficiency gain you'll ever get from any engine. Price is right too if you learn how to do it. Doesn't have to be perfect.. just closer than this number will ever allow, is all.
After all of that if you are still overheating when driving you might want to look at head gaskets, wrong direction water pump, or plugged rad.but I thought you said you had a new one, it's not like it's a built motor that is on the ragged edge or anything.
mrmalina99: You might want to check your ' evaporator ' .. if it's clogged it would cause the conditions you've described and to keep tabs on your temp I'd recommend a electric temp gauge be installed. Just a thought. Cometized (Chip)
Yep! Condenser .. I just replaced an evaporator in my truck ( huge job - under the dash) .. I also replaced a condenser in the '70 Maverick. The stock unit was s0 dirty that I didn't want to hook it up to the NEW vintage AC system and corrupt it. I've replaced the condenser in my Grabber on one of the HRPT tours when a 'wrench' that fell out of a car in front of us bounced off the road and took my unit out . Also , on the temperature gauge, we have had several mechanical Auto Meter Temp Gauges ' stick ' in one spot . We've since used the Auto Meter ELECTRIC gauges and haven't had any problems. They work great. Cometized (Chip)
I've got a dumb idea that I don't know if it's possible but can the Volvo fan be wired backwards? Pushing instead of pulling. Buddy of mine had something simular he had reverse rotation waterpump with a regular flex fan and basically had the same overheating issues as you. Just a thought.
It is possible to wire backwards and make it a pusher, I have checked and fan is drawing air through radiator.
I was looking at my belt routing tonight and realized that I have very little belt that makes contact with water pump pulley. Wondering if maybe it is spinning pulley at low rpm but at higher rpm (highway) its slipping. Thoughts? Logical?
Your belt looks ok to me. (Pic of fan shows it) Grab your water pump pulley and see if you can make it slip by hand. Make sure your radiator cap is good? Sounds like you have covered everything in this thread. You really will not know the truth of your engine temp without a gauge though. What a head scratcher!
