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Overdrive pulley

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

  1. RagTop

    RagTop Old Grumpy

    I just ordered an overdrive water pump pulley on line to address some of my heating problems and now I'm wondering if I did the right thing. It is a 15% overdrive pulley designed to work with my stock alternator and power steering unit brackets, but I'm now wondering if it will throw an excessive load on my p.s. pump, my alternator and my water pump bearing. Also, I just had a mechanic replace the V belts on my car and I am hoping that the drop from a 6.37" pulley to a 5.4" pulley will allow me to adjust the difference.

    Oops! I should have taken the time to think this through. Since the crank pulley remains the same diameter, neither the alternator or the p.s. pump will spin any faster. Just the fan. And I just removed the V belts and the alt and the p.s. pump were adjusted all the way out, so I'll have to drag the belts down to NAPA and see if I can come up with belts that are about 1" shorter.
    Last edited: May 15, 2017
  2. kb3

    kb3 Well-Known Member

    I would not expect any extra load on the other components. I am not familiar with the water pump overdrive pulleys, but assume others are. I am not certain that spinning the fan and the water pump 15% faster are necessarily a good thing. Assuming you are not making high speed runs on a regular basis all should be good.
  3. Horseplay

    Horseplay Well-Known Member

    If this should not work out I recommend a change in water pump to a Flowcooler brand. They flow greater volume at idle and low rpm where most overheating conditions originate without risk of cavitation and other probable issues over spinning a stock pump can cause. This assuming all other probable high temp issue causes have already been ruled out, of course.
  4. RagTop

    RagTop Old Grumpy

    Yeah, this car has been an overheating problem, after being run hard or in high ambient temps, since I bought it 19 years ago. I've already done almost everything I can think of including, but not limited to, a fan shroud, Flex-A-Fan, followed by a five bladed Ford fan, Water Wetter, three row radiator core, high flow aluminum water pump, etc. Since the car will heat up in a drive thru line or at a stop light, I've become convinced that Ford under designed the cooling system (radiator too small), and my mods, like a more aggressive cam and a .040 overbore, have contributed to the problem. A Mustang club member who also owns a Mustang restoration and repair shop in Shingle Springs, CA, where it's just as hot as it is here, said he had a client with the same problem and the overdrive pulley solved it. I bought a black anodized aluminum pulley to try to maintain a somewhat stock look for just under $100 shipped. I'm heading to the local NAPA store today to buy a pair of V belts that are about 1" shorter each to compensate for the smaller size of the new pulley. I'll let everyone know if it worked.
    Last edited: May 16, 2017
  5. kb3

    kb3 Well-Known Member

    I certainly hope that this solves your problem. If not, and assuming that the three row radiator is still a brass unit, I would highly suggest trying a two row aluminum radiator from Engineered Cooling Products. It was the best $200 I have spent to date. http://www.speedcooling.com/1967-1970-Mustang-Aluminum-Radiator-22-DS-Outlet.html I understand that you want to keep your car somewhat stock looking, but this may be a cure. We are running a fairly high horsepower 302 and have not had a cooling issue yet. For a frame of reference, I live in Modesto and the car has been in many cruises in 90-100F temps and stop and go traffic. It has never pretended like it was going to get hot.
  6. Horseplay

    Horseplay Well-Known Member

    Just throwing this out there...

    More than one head gasket has been put on incorrectly (backwards) on a SBF. guys have been known to check hot/overheating problems for a long time before finding out about this "oops".
    If you don't know for sure take a IR thermal tool and measure the temp of the heads both at the front and rear and compare the numbers. Really high temps in the back are a good sign of a gasket issue. Depending on the gaskets used, a visual check could show a square corner protruding in the front on BOTH heads and nothing in the back.

    Doubt this is the case with yours if you've been driving it for 2 decades but worth posting in case others are searching the same issue.
  7. JD08

    JD08 Member

    You could always try an 8 vane water pump. That was Ford's solution on the early K code cars.
  8. RagTop

    RagTop Old Grumpy

    Thanks for the reference and the empirical experience with the product. If it comes down to it, I've been looking at a 3 row MaxCore aluminum radiator that has the top and bottom tanks stamped with the same pattern as the stock Ford radiators. The one for my Mustang is about $300, so I will have a look at the Engineered Cooling Products radiator as well.
  9. RagTop

    RagTop Old Grumpy

    Yeah, I know a reversed head gasket can be a real source of problems, but I put them on myself back when I was a young enough guy to be trusted.:)
  10. Horseplay

    Horseplay Well-Known Member

    You won't like the look of it but it is a damn good radiator. Be careful of thinking more rows is better. The two row ECP, for example, has much more actual "surface area" from which it disappaites heat than any 3 core I ever looked at. Many of the three core style are VERY poor performers in comparison. The only problem for guys like you is that it is a very modern looking design that could never pass as a Ford unit.
  11. PetesPonies

    PetesPonies New Member

    The cooling systems on many of the early Mustangs are marginal. A proper cooling system should be able to over cool an engine. The thermostat then just controls this. However, in your situation something is going on. You covered all the usual culprits. I wouldn't be looking for the next trick. I wouldn't overdrive the water pump. I feel your problem is in the engine.
  12. RagTop

    RagTop Old Grumpy

    So, my local mechanic who installed the aluminum water pump I provided them along with two new belts, must have broken the fan shroud during the process. I purchased a new fan shroud (for which I'm going to charge them) and installed it myself because I don't trust them anymore. During the process I removed the fan, spacer and the stock water pump pulley in anticipation of the arrival of the overdrive pulley. Then I remembered that I was supposed to go to a show on Saturday and the pulley and new belts won't be here in time. I decided to re-install the old pulley and belts and everything went together just tickety boo. When I tried to start the car it made this horrible screeching sound and refused to run. I checked the clearance on the fan blades one more time and eyeballed the engine bay to confirm that there were no loose tools left in there. I tried to fire it again and the same screeching sound. I forced it to run briefly and was able to see sparks emanating from the front of the engine. Fan blades don't make sparks on plastic shrouds and there's no sign of striking anywhere. I did replace the alternator bracket with a new Scot Drake model because my old chrome ones were rusty and peeling. The guy sold me a set of C5ZZ brackets and assured me that, even though the post '67 Mustangs utilized a C8ZZ part that they were essentially the same. So, I'm sitting here in front of my computer in a generally depressed mood. The things I did were flat simple bolt out/bold in and everything seems to be seated properly. The belts seem nice and tight with a little depression (1/4") when you push on them. I live alone and don't have anyone to stand in front of the car while I crank it and I can't find my remote starter since we moved five years ago. Any suggestions as to the cause of my problem?
  13. kb3

    kb3 Well-Known Member

    Take the belt off and turn each accessory by hand. That should quickly point to the problem.
  14. JeffTepper

    JeffTepper Well-Known Member


    Try Ken B's suggestion to see what you get.
    My first guess is the new alternator bracket is scraping the alternator fan
    Second guess is the radiator fan blade is backwards and scraping something
    Third guess is at least one pulley is scraping another pulley.
    Good Luck

    Regards, Jeff
  15. Starfury

    Starfury Active Member

    While generally frowned upon, I often resort to a screwdriver to jump the solenoid B+ terminal to the small S terminal as a "remote starter." Just make sure the key is off, or the engine will keep running;)
  16. c6fastback

    c6fastback Member

    Did that to bump the motor on an engine install to fix the flex plate / converter error and I blew up my battery ! Did not help that the battery was more than a bit low on fluid .
  17. Starfury

    Starfury Active Member

    That's exactly why it's frowned upon, unfortunately.
  18. tarafied1

    tarafied1 Well-Known Member

    I know there has been some discussion on the overdrive pulley. My 67 with the 429 has always run hotter in traffic also. Mostly because it's so big I think airflow thru the engine compartment is very restricted but anyway, I have done all the same things. I used to run a copper/brass 4 core made for a 428 68 Mustang. I had underdrive pulleys and only an electric pusher fan. It wasn't enough but there isn't enough room between the radiator and water pump for a proper fan like a clutch fan. I did add a 17 inch "flex" fan and a shroud at some point. This helped but didn't solve the problem. I switched to water wetter and 15% anti freeze and again it was a step change better but not fixed. I bought an aluminum two core radiator and with the electric pusher, mechanical fan & shroud, water wetter, etc. I still saw some tendency to get hot (not overheat). It would get as high as 230 if I let it. I recently replaced the stock water pump with an Edelbrock aluminum water pump that is supposed to be a higher flow and then I replaced the water pump pulley with a slightly overdriven pulley. I haven't done a lot of testing yet but I bought a temp gun and some test strips that change color based on the temp they reach. One hot afternoon I ran the car for a half hour in drive at idle in front of the garage with the door closed and obviously the hood closed. After a half hour I checked the temp test strips on the radiator tank, the cylinder heads and used my temp gun as well. The radiator was 190, the heads 220 confirmed by both methods. So I think I might have a cooling system that works. My fan is set to come on at 180 and I have a 190 T state. I wired the fan with relays but not on a switched power so it will stay running after the engine shuts off. I forgot the off temp but it does shut off so it won't run the battery down. The overdrive pulley might not fix your issue if it's an engine problem but may still help. Below is a clip from an article that convinced me to try the pulley
    Last edited: May 19, 2017
  19. RagTop

    RagTop Old Grumpy

    Sounds like you and I have been over a lot of the same ground. I've been warned about excess flow through the radiator that is "caused" by my 160* thermostat, but your excerpt from the article would deny that. My personal read is that Ford was cheap and didn't provide enough radiator capacity for these cars. Sounds like you might have a solution with the overdrive pulley. My engine runs great and uses 0 oil after 50K miles on this rebuild. The car had the same tendencies prior to the rebuild.
    tarafied1 likes this.
  20. RagTop

    RagTop Old Grumpy

    I took the good advice given and took off my belts and tried to rotate each pulley. The problem was the fan which must have been striking the new shroud. I removed and remounted the shroud and the problem is gone. That notch in the bottom of the shroud to clear the lower hose is a b***h to get aligned properly and that must have been my error. The mechanic has cut me a check for the replacement shroud and they are ordering up a set of new wires. It seems that they "diagnosed" my problem that I originally brought the car in for, a miss under load, as crispy wires due to the headers. They replaced my black wires with a gray set from NAPA and left them on the headers. At least the gray wires were easier to see the burns on. I'm going to have them install a pair of wire looms that bolt to the middle of the valve covers to keep the new wires off of the headers and then I'm going to have them come out on a drive with me to see if the miss is gone. With the electric cutouts open you can still hear the miss bigger than hell, but the burned wires could still be the cause.
    tarafied1 likes this.

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