1. Hello there guest and Welcome to The #1 Classic Mustang forum!
    To gain full access you must Register. Registration is free and it takes only a few moments to complete.
    Already a member? Login here then!

Overdrive pulley

Discussion in 'General Mustang Discussion' started by RagTop, May 15, 2017.

  1. bartl

    bartl Old Fart

    IMHO, the "marginal" cooling issues with early Mustangs is more often than not caused by some deficiency in the cooling system or tuning, such as....

    a. Poor quality radiator (too little tube area or insufficient fins per inch density).
    b. Plugged radiator tubes.
    c. Radiator painted with enamel paint.
    d. Poor quality water pump (poor impeller design, supply holes to block not indexed well to front cover).
    e. Lower radiator hose closing due to pump suction at higher rpm (lack of spring).
    f. Insufficient spark advance.
    g. Too much valve lifter pre-load.
    h. Restricted exhaust system.
    i. Rust and scale in block (flush with "Shout" laundry spot remover followed by "Mercedes Douche").
    j. When it's a Cleveland, not using the C-specific thermostat and block-off plate.
    k. V-belt slippage.
    l. Mismatch of steam holes between block and heads ("early" block and "late" heads or vice-verse).
     
  2. RagTop

    RagTop Old Grumpy

    Excellent compendium of reasons why engines overheat. All those, and more, have already been addressed. For example I pulled the 3 row radiator last year and had it flow checked by a local shop. He flowed the water both ways and got nothing but clear flow. His professional opinion was that it was the cleanest radiator he had ever seen. I'd been running distilled water and Water Wetter in it. The water pump was just changed out from a stock unit to an aluminum high flow type. The advance is 14* initial to correspond to my custom curved '68 J code distributor. The block was hot tanked 50K miles ago and the coolant is clean as a whistle. The V belts are brand new. The heads, head gaskets and block all line up regarding water passages. I also added a fan shroud and a five bladed Ford fan which I confirmed is half way into the shroud and about 1.25" from the back of the radiator after changing fan spacers. The 160* thermostat has been visually confirmed to work by observing the movement of the coolant in the top tank while monitoring with my infrared temp sensor. I'm taking a crack at the overdrive pulley on advice from a fellow Mustang club member who is also a professional mechanic. Said it worked for his wife's '66 fastback. The pulley has arrived and the shorter V belts are on the way. I'll let everyone know if this worked.
    IMHO, the problems that 60s Fords have with maintaining temp when idling is due to the fact that the 20" radiators that small block non A/C cars were equipped with do not have sufficient volume to keep the engine cool at idle. If the engine heats up when there's no air being forced through a clean radiator by forward motion, insufficiency of the radiator design jumps to mind for me. A radiator should be able to keep the engine temp, at idle, around the thermostat temp rating, allowing the thermostat to control temp by opening and closing, but if it can't dissipate the heat the engine produces, the thermostat becomes useless because it is always totally open. Maybe Ford shouldn't have used the radiator design from the Falcon.
     
    Last edited: May 22, 2017
  3. Midlife

    Midlife Well-Known Member Staff Member Moderator

    A 160* thermostat may be your problem; the original design was using a 198* thermostat, but most people use a 180*. If your system cannot cool the water below 160*, then the thermostat is always open and may lead to overheating.
     
  4. RagTop

    RagTop Old Grumpy

    It did the same thing with a 180* T-stat, but, if this overdrive pulley doesn't clear the problem up, the 180* T-stat will be my next step.
     
  5. bartl

    bartl Old Fart

    Definitely ditch the 160* thermostat. Ford installed a 192* unit so that engine oil temperature would rise high enough that any moisture (condensation) would boil off, the steam travelling through the PCV system, and also improving the lubricity and drainback of the engine oil. Will it cure your overheating problem? Only if the thermostat is defective, otherwise it only controls MINIMUM engine temperature. So, where do we go next? A few MORE questions.

    1. Are you running the OE dual diaphragm vacuum advance distributor? If so, is the DVCV (distributor vacuum control valve) properly installed, plumbed and operating?

    2. If you AREN'T running the OE distributor and are using a single diaphragm vacuum advance unit, where is it connected (ported vacuum or manifold vacuum) and is the DVCV being used?

    3. If you're not running the OE distributor and are using ported vacuum as a source for vacuum advance and are NOT using the DVCV then you should either switch to full manifold vacuum or reinstall a working DVCV and plumb it to switch to full manifold vacuum at hot coolant temps.

    4. If you're not running the OE distributor and ARE using manifold vacuum as a source for vacuum advance and need a bit more air and water flow at idle then consider installing an external Hot Idle Compensator as installed on 2V equipped cars with factory A/C. These are designed to install in the PCV line and cause a controlled vacuum leak at high ambient temperatures (under the hood) to raise the idle.

    IMHO, though, if you're getting hot at both idle AND cruising down the highway and the lower hose isn't being sucked closed by the suction of the water pump then I'd go back to suspecting insufficient spark advance and, possibly, lean fuel mixture as a contributor. FWIW, I've seen small block Fords that like a lot of total timing. My '85 5.0HO likes 44* at 3,000 rpm and up.
     
  6. RagTop

    RagTop Old Grumpy

    Just got the proper sized belts and the overdrive pulley installed and it does seem to do a better job of controlling the engine temp. I even purposely went to a drive thru after the car was at operating temp and it seemed to not notice at all. This would have been asking for heating up previously. My one problem is the stupid shroud. I have installed it three times now and twice, including this last time, the fan blades are striking the lower part of the shroud opening. The previous shroud, which appears to be, in every way, the same as the new one, down to the original Ford markings, was in and out of the car several times over the 19 years that it was in there and there was never a problem with the 17" fans, be it the stock 4 bladed model, the Flex-A-Lite or the present 5 bladed Ford unit. I've got a ton of space at the top, so I'm assuming that the fan is not centered in the opening. Are those threaded metal clips that fit onto the radiator moveable? I'm thinking of removing the top bolts on each side, loosening the two lower bolts and then tapping the lower metal clips downward. I can adjust the top clips as necessary once I've gained some space on the lower mounts. Am I missing something obvious here? This is starting to piss me off. Help.
     
    Last edited: May 26, 2017
  7. Starfury

    Starfury Active Member

    Been a while since I had my radiator out, but I recall the radiator mounting holes being slotted. That, or maybe I slotted them myself to allow for some height adjustment.
     
  8. JeffTepper

    JeffTepper Well-Known Member

    Slotting the shroud holes vertically will provide some additional up and down adjustment. Typically, 1/4" should be more than enough for fan clearance.
     
    tarafied1 likes this.
  9. RagTop

    RagTop Old Grumpy

    The shroud slots are horizontal. I did a little high tech mechanical work with a rubber mallet and it seems to have corrected the problem. The bottom of the shroud is sitting virtually on the transmission cooling lines and there's almost no room for adjustment. The fan blades now miss the bottom of the shroud by maybe 1/32". I did notice that the space on the top of the shroud was pretty minimal too, maybe a finger width, but the horizontal space was about an inch on either side. This kind of screams oval to me. I'm not sure why I have these clearance problems with this specific shroud. It's one of the Ford tooling products.
     
    tarafied1 likes this.
  10. RagTop

    RagTop Old Grumpy

    I promise, this is my final statement on this subject. The overdrive pulley seems to have been effective. I've been driving the car for the past several days in 90*+ ambient temperatures and it seems to be able to handle stop lights and slow traffic. My shroud issue is still in resolution, however. I'm running without a shroud at the moment, but, when I pulled the "new" shroud off of the car I discovered that the apperature for the fan was oval rather than round. It had virtually zero clearance at the bottom of the shroud and about 1/4" at the top, while both sides had about 1 1/2" clearance. The side that faced the radiator was warped downward on top and upward on the bottom, creating the oval shape. This was a genuine Ford tooling shroud, not some Chinese knock off. The fan had torn a chunk out of the bottom of the shroud and struck the top hard enough to crack it. My supplier presently has a replacement shroud on the way that he has confirmed is both round on the fan side and rectangular on the radiator side. I'm getting pretty good at pulling the fan and installing the shroud on this car. The mechanic who loused up my original shroud and cooked my new wires has replaced the wires. The car pulls hard up to about 3,500 rpm and then, when under load like a shallow hill, will begin to miss. I took the car to these mooks originally to diagnose the miss and they replaced the wires (twice) as their best judgment. I think I'm done with them but I'm still trying to find the source of that miss. I'm beginning to suspect that it is due to the Pertronix Ignitor or the Pertronix Flame Thrower coil.
     
  11. RagTop

    RagTop Old Grumpy

    OK, so I lied. The overdrive pulley is totally a fix for my Mustang's heating problems. It's been in the 106*-110* range up here and I'm running without a shroud and everything seems to be under control. The reason I'm running without a shroud is because the replacement Ford Tooling unit, that I visually verified was rectangular on the radiator side and round on the fan side before putting it in the car, sagged to the same shape as the first one in a couple of days service and the upper and lower areas of the shroud were struck and broken by my fan. The vendor is sending me a refund, but their source is the same as everyone else's nationally, so I guess I'm stuck with running without a shroud. I can only surmise that the plastic formulation that the maker is using in the Ford tooling is sub-standard. The old one held up for about 19 years with three different fan configurations until my mechanic's elbows did it in.
     
  12. 3175375

    3175375 Well-Known Member

    Only thing I will add is if your 289/302 block is bored .030 over you'll likely encounter overheating issues (ask me how I know).

    Steve
     
  13. RagTop

    RagTop Old Grumpy

    Actually, mine is .040 over, but it had heating problems before it was bored.
     
  14. 3175375

    3175375 Well-Known Member

    Ragtop, where did you get your overdrive pulley?
     
  15. RagTop

    RagTop Old Grumpy

    Last edited: Jun 24, 2017
  16. 3175375

    3175375 Well-Known Member

    Thanks, Ragtop. Parts are on their way for my continued experiments.....
     

Share This Page