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Just bought some March Underdrive pulleys, but have been reading some negative things about underdrive pulleys in general and now I'm debating whether on not to have them installed. If it matters I have a 1997 4.6L T-bird. Does anyone else have these installed on a 4.6L?

Am I going to notice anything like lights flickering, a/c not working, or radio volume going up and down? If so then I think I'm not going to bother having them installed.

Ty in advance.
 

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I have them and have no issues. I have heard bad things also but have been running them for almost 6 years. Most people avoid the piggyback crank pulley.
 

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4.6 U/D Pulleys

There are literally millions of underdrive pulleys installed on 4.6L engines in Mustangs (I believe they even came STOCK on some years), and those are abused far more than our Thunderbirds (I'd like to think LOL). The only negatives that people sometimes experience:

1) Poor charging due to slow alternator speed at idle (your alternator should be spinning at LEAST 2000 at idle for dependable adequate charge). This can be fixed with a slightly SMALLER (overdrive) pulley installed on the alternator (can be bought for less than $10 on eBay).

2) Overheating in hot environments. Logic would tell us that automakers design cooling systems the cheapest they can to maximize profit, but they still have to work. This results in marginal cooling systems at best. You slow down the water flow and you could cause less heat to be dissipitated. I say try your particular application and make sure that isn't a problem. Go with a Cobra radiator & Mark VIII cooling fan if this becomes an issue.

3) As XR-7 already stated, shattered trigger wheel & oil pump gears. The newer trigger wheel is stamped steel and much stronger than the cast stock wheel if this happens. Oil pumps gears I don't know about, but I'm sure there is something better/stronger for that as well.

Lots of people say piggy back pulleys are a bad idea which only makes sense when you think how these things are spinning 100 times a second at 6000 RPM. That's why I'm going with a fluidamper solution.

My only dilemma is the following:
March offers a fluidamper that is a 6" SFI certified underdrive pulley.
KMJ Performance offers a fluidamper that is a 5" SFI certified underdrive pulley.

Obviously, you'd feel more "punch" with the smaller pulley, but these are china made stuff we're talking here. March is a better brand in my opinion, but they are bigger and less underdrive. I'm still debating on which one to get.....
 

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just curious after you install the u/d pulleys can you actually feel a bit more punch or is that like the throttle body and bigger MAF crap where theres "supposedly" better kick?
In most cases, and certainly not with these cars, you can't feel it.
 

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In most cases, and certainly not with these cars, you can't feel it.
Are you being sarcastic, Chris? Or serious? Cause I've read that the difference is not as pronounced on a modular engine as with older engines, but a lot of people claim it's one of the best "first mods" to get.

So, please enlighten me before I do this. And I'm gonna do it regardless, and let you know what I "feel" lol! :thumbsup:
 

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No, I'm being serious. I run Steeda ones on my car and it quantifiably helped my gas mileage, but there was no difference off the line. The claims of 10 HP from UDPs is always at high RPMs when all the accessories are really winding up and parasitically dragging, but from a stop or lower engine speeds when they aren't spinning that fast to begin with, there's hardly a difference.
 

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I have the Steeda 3 pc set and had no problems with cooling or Alt. Did feel a bit more grunt(small but there). And gas mileage did pick up by about 3mpg or so.
 

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I have the Steeda 3 pc set and had no problems with cooling or Alt. Did feel a bit more grunt(small but there). And gas mileage did pick up by about 3mpg or so.
3 mpg improvement with only UD pulleys..... That seems hard to believe. :beek:
 

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I do alot of stop and go traffic on my 18 mile drive to work. So I contribute the gain in MPG due to the less idle speed drag on the engine.
 

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That's friggin' amazing!! 3 mpg gain around town. Impressive! :thumbsup:
 

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I installed a u/d crank pulley on my 86 f-250 hd (302 roller). Definitely improved all around - mpg , dead stop and rev faster. The old one was a steel double pulley that was about twice the size.
-Robert
 

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I have the trickflow set the volts do drop which effects the a/c and headlights but setting the rpms to about 900 fixes the problem
 

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oh and yes i did notice a power gain. The install takes about an hour if youve got an impact and a tork wrench so you may just want to do it yourself : D
 
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