Serpentine Belt Issues...Gilmer style cog belt for SBF?

Discussion in 'General Maverick/Comet' started by 72MAVGRABHER, Apr 22, 2018.

  1. 72MAVGRABHER

    72MAVGRABHER Maverick Mechanic

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    Anyone running this type of setup on their sbf 302/347’s? I’m having belt slippage bad on my 347 that we converted to Serpentine belt from 1990 LTD. I’m only running polished summit 100amp 1 wire alternator, edelbrock victor jr aluminum water pump and crank. I have alternator as tight as I can get it and still squeals and eventually snaps belt.

    Also for people running serpentine kits or even this Gilmer style, I’ve noticed some kits come with a threaded double eye bolt for bottom alternator rather than flimsy regular brackets, does this make a big difference?

    I’m open to ideas on adding a idler pulley and a tensioner pulley to setup to help stop slippage, what tensioner did you guys pull from (what’s the part #?) thanks for help guys. I really like the Gilmer pulley kit and price is right if I can make work.
     

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  2. bmcdaniel

    bmcdaniel Senile Member

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    I tried to run the gilmer setup once, the water pump pulley was too long and hit my electric fan. Now I have a serpentine belt from a late 80's Crown Vic. No tensioner because it's for a standard rotation water pump. Just tighten by moving the alternator like a v-belt. Have you used a belt tension gauge to accurrately adjust the belt? Does the alternator have a polished or chrome pulley?
     
  3. 72MAVGRABHER

    72MAVGRABHER Maverick Mechanic

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    The only way to tighten is by moving alternator. Yes on tension gauge. Alt came with polished pulley but swapped it for stock 1990 crown Vic LTD pulley when I swapped to serp setup. Due to my high compression/high HP and higher rpms, i’m still getting excessive slippage until it snaps. Have tried using New Dayco, drive rite, Napa, oreilys, Gates, Jason and autozone name brand belts all with same result. It’s been laser aligned from Gates so it’s not tracking off in anyway.

    I would have same issue with Gilmer 1-1/2” belt being wider so it will hit my Efan as well possibly, but I have recessed aluminum radiator into support to buy Few extra inches so if this 1:1 works/fits on my engine I think it will be way to go since my water pump is under driven currently and have had issues with it heating at low idle stoplights.

    Anyone else used Gilmer cog style and possibly pictures of setup in your car? Thanks
     
  4. Rick

    Rick G8I operations

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    Compression and HP wont effect it, RPM's might if your spinning it to 10k. Take a look at the alternator and try switching it. I had one that keep squelling, we thought it was the belt turned out to be bad bearing in the alernator.
     
  5. bmcdaniel

    bmcdaniel Senile Member

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    I kinda remember now when I put the Crown Vic pulleys on mine I had a squeal, too. Turns out it was the pulley turning on the alternator shaft. The shaft isn't keyed, just relies on the clamping force of the nut.
     
  6. Shorty

    Shorty Member Supporting Member

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    I have a Gilmer belt running the water pump & alternator. I will transfer it to the 347 we're installing soon. I removed the power steering and A/C because they both leaked. No problems whatsoever and it sounds a little bit like a gear drive. I ended up replacing the factory flex fan with a Flex-a-lite I had hanging on the wall but plan to replace that with an electric fan. For the keen eyed, I finished the lower alternator bracket after the picture was taken.
    IMG_3389.JPG
     
  7. Krazy Comet

    Krazy Comet Tom

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    Sounds like crank pulley is doesn't have any grip or you are spinning excessive mass (how large is this alt?)... Overcharging will cause belt to squeal...

    I owned a 5.0 Grand Marquis with that belt set up, replaced belts maybe once in the life of the car...
     
  8. 72MAVGRABHER

    72MAVGRABHER Maverick Mechanic

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    Shorty can you give me dimensions/specs on your crank and alternator pulleys. I’m assuming they’re 1:1 style. My crank pulley from crown Vic LTD is currently 7” round and alternator is only 3” round with sides and only 2.25” round on belt ribs with water pump at maybe 5” but I’ll have to wait for daylight to check 100%. Do you have a part number for your kit?
     
    Last edited: Apr 23, 2018
  9. 72MAVGRABHER

    72MAVGRABHER Maverick Mechanic

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    Crank pulley has some shine to it where it’s been slipping. The alt is the summit polished 100amp 1 wire alternator with built in voltage reg. It fits standard factory brackets. I’m not paying $300+ for a March setup and if I go double vbelt style I might as well go this Gilmer cog i’m just worried it’s gonna spin my water pump too fast and aerate the coolant as I don’t want to over spin the water pump since it’s already a victor jr aluminum that’s built for 25% faster rotation.
     
  10. 72MAVGRABHER

    72MAVGRABHER Maverick Mechanic

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  11. groberts101

    groberts101 Member

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    I have a couple comments. First one is relating to the need for the gilmore setup vs the conventional v groove or the serpentine setups. Many have used those stock style setups with far more aggressive combos without issue. I'd be looking at the causes.. not the cures.

    Next is the overheating you mentioned earlier. Unless your belt is slipping so severely during idle and light throttle?.. that usually points towards a timing related issue. Generally relating to retarded timing which is known to cause overheating. If not already connected there?.. hook the distributors vac advance to full manifold vacuum.. NOT a timed/ported source which provides no supplemental ignition advance at idle and very light throttle angles. Manifold vacuum will rise, mixture will lean out(usually requires mixture screw readjustment and reducing idle speed) and the motor will put out less heat during idle and light cruise speeds. I try to run underdriven crank pulleys on anything performance oriented.. never an issue with overheating even on 500+ horsepower apps.

    Last is the comment about the ebrock pump being overdriven. Not sure where you heard or read that.. but the impeller design itself cannot account for such a term. It's generally considered to be a higher flow low drag anti-cavitational design but the waterpump pulley to crank pulley ratio is ultimately what controls the under or overdrive ratings.

    Just adding another perspective.
     
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  12. Shorty

    Shorty Member Supporting Member

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  13. groberts101

    groberts101 Member

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    Other things you might check before tossing parts at this issue. Remove belt and check wear patterns on all pulleys. With belt removed check rotational resistance of ALL accessories being rotated by it. Alternator should spin fairly easily with no field charge.

    Another issue I have seen many years ago with some of the 5.0 guys doing serpentine conversions with mismatched and fabricated setups is the use of very high mounted alternators on standard rotation pumps. IIRC, and I may not after so many years, some of it had to do with the alternator locations causing a very small belt contact patch on the water pump pulley. Like 1/3 or less of its diameter, only the top corner. I believe my bro-in-laws 85 race car had similar issues with some type of chicom fancy looking billet alt brackets used before he converted to the e-pump. True serpentine belt setups using reverse rotation pumps obviously have much greater contact areas and the added idler pulley kept things copacetic.

    And finally.. the bandaid trick. Voids belt warranties but it most definitely works as advertised on industrial and race car belt in a pinch. If you're potentially going to swap out parts anyways.. not much to lose really. Called "belt dressing" and is sticky, and stays sticky as hell. Not exactly sure what the composition is but it is non-drying non-hardening and works for quite a long time with only minimal amounts required. I do remember that acetone or laquer thinner with a tooth brush removes it. Along with any paint too. lol I tried it a couple times through the years, believe I may still have the 25+ year old can stuffed in my oil cabinet, but I will tell you straight away that if you live in a dusty environment or travel gravel or sand roads.. that stuff loads up with dirt quickly! Just another option to try. Hope all this helps at all.
     
  14. 72MAVGRABHER

    72MAVGRABHER Maverick Mechanic

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    The cause mainly is that i’m running only 3 pulleys (no PS or AC) with no idler to help maintain optimum belt coverage on water pump pulley as stated above. Instead of adding an additional idler and fabbing a bracket, the Gilmore setup would eliminate this issue. The statement about my water pump being over driven is the fact that it has a smaller than stock pulley causing the cavitation at higher rpms even though the pump itself is designed to lessen that effect as you said. Timing is spot on. I have lost my original vbelts setup, so i will have to buy pulleys regardless. If anyone has a part number for an idler/bracket combo (like an AC delete) they’ve used, then I’d be open to staying with the crown Vic pulleys once alternator bracket is replaced. Once I get new bracket for alt I’ll go ahead and swap to old style vbelts or this Gilmer style otherwise. Thanks for input guys
     
  15. groberts101

    groberts101 Member

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    Are you running an aftermarket alt mount? If you were to use the oem style alt mount setup shown in shorty's pic above.. it would likely create a larger belt contact patch due to the lower mounting position and avoid further mod's or parts.

    And curious since it seems to be so subjective, what initial timing #'s do you consider to be "spot on" for your combo?

    Examples. This one is bad.. too high.. causes poor contact zone on water pump pulley.

    https://www.customcrateengines.com/...-crate-engine-380-hp-with-aluminum-heads.html

    This one is much better.. more contact zone for pump pulley.

    https://marchperformance.com/ford-2...on-w-p-serpentine-bracket-and-pulley-kit.html
     
    Last edited: Apr 23, 2018
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