68 Mustang over-heating after upgrades

Discussion in 'Classic Mustang Specific Tech' started by jerthemost, Jun 12, 2011.

  1. I have a 68 mustang coupe on which I recently had several upgrades done and now have an overheat issue. I have another thread on here concerning steam vent holes and heat. My car went back into the shop and had a head pulled to make sure the steam vent holes were drilled and we found that my block already had triangular shaped holes where edelbrock said to drill holes so that was not the cause of my over heat issue.

    I had edelbrock heads installed as well as edelbrock matching cam. I already had a performer intake with 4v 500 cfm edel carb. I also have flowmaster dual exhaust with stock cast iron headers. Ignition is vac advance distributor with pertronics igniter. New plug wires. My radiator is over size copper 2 row 24x17 core with 6 blade 18” steel fan no clutch. The mechanic did put a restrictor with 5/8” hole in place of thermostat. I did have hi flow water pump installed when they did cam.

    When I got the car back after upgrades it was running much hotter than before upgrades. I stalled a temp gauge with numbers and did test drive. In 4 miles I hit 210 degs with 95 outside and no a/c on. After idling few seconds went to 220 degs. I got gas at local store and headed back home. On the way turned on the a/c and when I stopped at my gate I hit 230 and shut it down.

    I verified that head gaskets were on right and heads were on right. Then issue of steam holes came up. They did not drill holes so it went back to shop and found holes already there on my block. My block is C8OE. But for a week before it went back in I prowled the forums and talked to a very car savvy friend in Georgia. Forums said check gaskets, water flow direction, timing, mixture etc. One post said bleed air out of cooling system. I removed rad cap to check flow direction and had good flow at fast idle but noticed extreme air in system. Had foam coming out of radiator. So I warmed it up to 185 while massaging top rad hose and burping lots of air. I then let it cool down cranked it did it again. I did this 3 times total.

    A couple days later I took it back to the shop to check for the holes. On the way there it was 80 outside, I left a/c off and drove 45 not over 50. The temp for 10 miles to town stayed at 175. When I hit stop light temp immediately went up to 180. I went through small town at 35 and then hit highway and went up to 55 mph. Temp stayed at 180 for 2 miles to RR track where I stopped and eased across. Immediately temp went to 185 and stayed there until I got to the shop 4 miles later.

    Mechanic is installing hi flow thermostat in place of restrictor. And I asked him to verify timing and mixture.

    So on the highway it was not bad after burping the air out but at idle it shoots up very fast. I don’t know how high it would have gone if I had to idle longer but it is worrisome that it goes up so much so fast. So I guess my question is should I put an electric pusher fan In front of radiator to help out in traffic or what? And if so does anyone know what amp the stock alternator is? I assume I will have to have a bigger alternator. If I do need new alternator what do you suggest?

    All thoughts on subject appreciated.
  2. What temp high flow Tstat is going in? I would suggest 180*-195* range, have heard good things about the Stewart ones. I take it you have a fan/shroud, at least 3 core rad., 24" vs. 20" rad? Coolant mix? Are you using water wetter? Have you verified that you have the correct water pump for your timing cover with the correct vane/water flow direction? Many wp are misboxed.

    An electric fan pulls a lot of amps every time it comes on, i've read 30-60 amps depending on which one you get. The stock alt. is normally 45-65A so you can see the issue with one accessory taking most of that. You have the option of switching to a 3G 1 wire ~130A which takes some wiring changes and eliminates the external VR. I installed a mid 70's Ford/linc/merc 100A 1G alt. which looks similar to the stock one, just larger case and uses the same 3-4 wires and stock ext. VR.
  3. I'm wondering why you're asking any of these questions while that stupid restrictor is still in there. You'll know a lot more after you get a proper 190° thermostat in there. It takes maybe a half-hour to install a thermostat. If heating up at idle is still a problem after that, install a shutoff valve in the heater hose between the intake manifold and firewall, and install a factory-style distributor vacuum control valve in the thermostat housing. This simple system increases idle speed to cool the engine if it begins to overheat.

  4. Doing this now

    I am doing this now because i have no confidence that a thermostat is going to solve the whole problem. I have added quite a bit of HP and we are having extreme record breaking heat here in Houston Tx. We broke records for first 6 days of June and had 2 105 days in a row. I have to be able to run the a/c. So I want to be ready when i get the car back this week to tackle the heating issue.

    As for the radiator it is only 2 core. I am going to take it to rad shop, have it cleaned and ask about adding third core. It has provisions for 3 cores. It is 24" x 17" core. I still think in this extreme heat that i will need electric fan.

    About the idle control valve that's good info to know. I had one in the original water neck and took it out when i installed new carb because the carb instructions said to hook up advance to carb. I cannot put connection in heater line because i cannot leave heater valve open in summer because it will overload a/c. A/c will not be able to keep up in this heat. My heater line also has a manual positive cut-off.

    As for the water pump it is supposed to be correct for the car. It fits as far as i can tell and the water flows from passenger side to driver side. It appears to be flowing good at fast idle but no noticable flow at slow idle. That is curious but how can i tell if the pump is the right one and if it is ok?

    But thanks for the input we are off to a good start, thanks.
  5. sorry i missunderstood about control valve

    didn't catch part of that last post. I do not have a place in thermo housing to put control valve. I installed a new chrome housing. I still have the old iron one and can put it back in if need be but stiil instructions on carb say to connect advance to carb. I can talk to edelbrock about it. i don't see what difference it will make as far as carb goes. It might be better to do as you suggest.
  6. Higher horsepower usually means higher temps, you need to start with the cheapest item first and go from there. I live in muggy louisiana so I know the Heat you are dealing with. Are you paying a shop to do this work for you? If you have the money then go for it, but a thermostat, radiator replacement, etc...is really easy work to do on your own in an afternoon, anyway, if the thermostat don't work, you need a fan clutch and a shroud. MY recommendation, seeing how you are in town a lot, just go ahead and get a 2 row (1" rows) aluminum radiator, upgrade your alternator, get an electric (thermostat operated & A/C operated) fan. You can put all that in your car in a weekend easy. I have a 67 289 A/C and my car never gets over 185....even idling! Spend the money, do it right, over-do it a little in case you want to do more upgrades later.
  7. The valve has no effect on the carb, or visa-versa. One of the simplest hookups is this one, which would be quick and easy to install:

  8. Over heating at idle is an air flow problem, over heating at speed is a water flow problem. Also, I would recommend a three row radiator and if you don't have a shroud, install one. Or a good pusher fan will help. If you add an electric fan it is advisable to add a higher output alternator. 230 is hot, but cars with an idiot light wont turn on the light till it hits 240. On a 100 degree day running 200 to 220 isn't over heating. As a friend of mine who owns a radiator shop told me, "If it isn't boiling over, it's not over heating." I live in El Paso, and if you can get a car to run under 220 on a 100 degree or higher day in traffic, you are doing real good.
  9. One more question, what PSI radiator cap are you running? Also is it a functioning radiator cap? If you have an original heater core and original radiator a 6-7lb cap is the max I would run, but if it has been replaced in recent years you can raise the boiling point by installing a higher psi cap, somewhere in the 12-16lb range. Note: If you do this on an old radiator or old heater core you may very well blow a seam in them.
  10. You need a better radiator. The two-rows are marginal for anything more than a stock engine. Sometimes they're marginal for those, too. Oh, and ditch that coolant orifice for a proper thermostat.

    Get at least a three-row high efficiency(not the same as a regular) brass or two-row aluminum. I don't know what fan you're using, but I found that there can be significant differences between stock fans than look identical at first glance.

    I have one of those valves I have been meaning to install. Is the line going to the carb supposed to be ported vacuum? All my original vacuum lines are long gone, so I don't have any colors to go by.
  11. I know you are up to your ears in good advice here, but here is another tidbit I have to throw out there, a little radiator 101. Lots of racers and guys use aluminum radiators, aluminum as a metal, does not cool as well as brass (it does not conduct the heat as well) But the benefit is that they can make the coolant tubes in an aluminum one wider, so if you do decide to go aluminum, make sure it has at least 2 rows of 1" tubes, not 3 rows of 3/8"s tubes, this defeats the purpose of going aluminum....if you want a 3 row, get brass. Ebay is full of aluminum radiators that are 3 row 3/8" so be careful.
  12. Car is out of the shop

    Got the car back today and here is the heating issue results:
    steam holes were already there. installed new high flow t'stat not sure what temp will ask later.

    From shop to home is about 20 miles. When i started it was at about 150 deg, had just been test driven, temp outside was 97, left a/c off. After 8 miles driving 55 stopped for light was at 195 deg went up to 200 while stopped. After 8 more miles at 62 mph got up to 209 still no a/c. Slowed for next 2 mi to 35 temp dropped to 200 still no a/c.

    have not checked for air in system yet waiting for it to cool down a bit. i looked for radiator shops in my area and cannot find any. Was told plastic rads put them all out of business. If i can find one what do you think about cleaning and rodding and add 3rd core or should i just buy new aluminum rad?

    i now have 2 core copper rad with 1" cores not 3/8". Could add 3rd core but like above have not found rad shop yet. This rad was made for cores and and is ford from some other car.

    so if i need new 3 core alum rad what do you guys suggest?
  13. Are you running a Fan Shroud?
  14. By the way

    My mech says i need different jets in my carb says it's running lean. I have a 500 cfm Edelbrock on performer 289 intake is what i told him to look for after reading some post from you guys. Then he said my distributor is chasing itself, he says he had disconnected vac advance before but has now hooked it back up and it just keeps advanceing. I also mentioned timing to him as a possible cause of heat issue. I also told him distributor might need recurve after a post told me it solved his problem so mech said i might need recurve but he cannot get parts. Is recurve needed after cam install? Sounds reasonable to me.
  15. Pull a couple plugs. It they are light brown then the jetting is probably okay, if they are chalky white it's lean, blask is rich. I have never heard the term "the distributor is chasing itself". Disconnect the vacuum advance and see if it runs cooler. From what you have discribed, it sounds like the cooling system is not adequate.
  16. I'm am glad the jetting and timing has been brought up. Make sure to use the graph in the Edebrock book only for jet and rod changes. Don't use Carter jets and rods.
    Make sure the dist. vacuum line is going to ported(gets higher when revved) and not manifold vac(drops when 1st revved).
    If it an Edebrock 1405 carb the vac advance port is on the left side(higher up) port looking @ the car from the front.Not to mention it will ADVANCE your timing @ idle ,a classic mistake done by many.
    Too much or too little timing will cause overheating.
    High vol water pumps "sometimes" move the water too quickly and not allow it to dissipate heat in the radiator.
    This was exasperated by not running a thermostat.
    Run it @ night and see if the manifolds’ "glow”. If they do there is too much fuel or retarded timing.
    I don't run straight cut cams in any small block Ford. I have also seen this make engines run hot.
    No disrespect to Vic , but i will check out the cam spec's next.
    DONT do more than one change @ a time so you know what works and does not work.
    Good Luck!
  17. Aluminum has about 100% more thermal conductivity than brass.