Metco Lower Pulley vs. Stock Caged Lower

[CobraTerritory]

Has there been any reported engine failures due to not having the crank support provided by the stock lower vs a Metco kit. I've got a 4lb lower metco on the car now but either going back to the stock caged lower or i can just purchase the stock size ring for the Metco hub (2.9 whipple soon). Just trying to get opinions on which to go with. My good buddy told me "There is a reason the factory did not just put a pulley on there without support?" What does everyone think?

 

[2003cobra22]

I recently talked with Metco asking some questions about there lowers. I was told by Metco the only reason failures have occurred is because a flaw in some cobra crankshafts that can lead to there failure regardless of the cage support or not. I need more substantial evidence than to take there word for it. I have a caged 4lb lower and believe the cage does take unnecessary stress of the front of the crankshaft. Though thousands of those lower kits have been sold and work fine. Just my 2 cents

 

[Senkak]

I have had a 4lb lower for 9 years.
Lots of street miles and a lot of drag racing with no lower pulley/crank issues.

 

[04sleeper]

Your buddy is correct. I know an engine builder that has been building mod motors since 96 and he can tell if a car has had an aftermarket lower pulley on it or not.

I have personally witnessed several crank snouts snapping off! ALL had aftermarket lower pulleys!

Guess what they replaced them with afterwards?

 

[2003cobra22]

I have had a 4lb lower for 9 years.
Lots of street miles and a lot of drag racing with no lower pulley/crank issues.

My luck wouldn't be that good this whole universe is against me :whine:

 

[SlowSVT]

Without a cage the #1 main bearing is taking-up all the lateral load imposed by all the accessory pulleys hanging 8" out in front of it. That can't be good, snapping crank snouts in this car is not unheard of. Any flexing here can also send the pump gears into the housing and I suspect this is lead to many pump failures.

 

[Rambro]

Won't the stock lower cause the same problems with the bearing when the bushings get worn out?

 

[SlowSVT]

Won't the stock lower cause the same problems with the bearing when the bushings get worn out?

The coupling between the outer pulley and the crank is rather loose to allow it to "float" so it only transmits rotary force and not lateral loads from the belt tension.

 

[Rambro]

The coupling between the outer pulley and the crank is rather loose to allow it to "float" so it only transmits rotary force and not lateral loads from the belt tension.

Gotcha. I always heard the uncaged lowers aren't an issue untill you start running the big twin screws. Rebuilding the stock lower is a pain supposedly but I guess it's better than risking internal damage with an aftermarket lower.

 

[SlowSVT]

Gotcha. I always heard the uncaged lowers aren't an issue untill you start running the big twin screws. Rebuilding the stock lower is a pain supposedly but I guess it's better than risking internal damage with an aftermarket lower.

True statement

The increased inertia loads of the larger blower are more prone to breaking cranks. A 2.3 might get away with it, a large blower is more of a "throw of the dice".

 

[03Steve]

I've seen four stock lower pulleys break from a 4.0L Whipple. I'd rather see 20 of them break before tossing one crank snout or front bearing. For once I agree with the gentleman from Pasadena.

 

[SlowSVT]

For once I agree with the gentleman from Pasadena.

The law of averages is at play here. It was bond to happen at some point.

 

[FiveOhJoe]

I wonder if you could modify a Metco kit to support the crank the same way the stock pulley does

 

[Rambro]

So is it safe to say that with an eaton and a aftermarket lower you have less chance of breaking the snout but you are still taxing the front bearing?

 

[JrSVT]

While there are cases of failed crank snouts due to the larger twin screws, I've also noticed that majority of the failures have been from people running aftermarket belt tensioners with the larger blowers. The aftermarket tensioners allow you to get the belt very tight and as we all know a tight belt doesn't slip...that is everyone's dream - to minimize belt slip. The problem is with the after market tensioners the belt is so tight that it adds more stress to the snout of the crank where the stock tensioner springs back and forth allowing some of that tension/stress to be absorbed through the tensioner....aftermarket tensioners reduce or eliminate the flex/springiness and all that stress has to go somewhere....the crank snout.

I would say a eaton setup with the stock tensioner and aftermarket lower pulley setup will last a LONG time. Even a twinscrew with the factory tensioner will last. Unless you have an aftermarket tensioner that you adjust to have zero belt slip, the Metco lower pulley setup will not cause your crank snout to fail.


Jr.

 

[svtshadow]

Everything breaks, question is, what are the odds of it happening to you? I mean some people have ran them for 8+ years with no issues and others just one track ran before they break.

 

[Quick Strike]

I had five years and 35K miles with a 4# lower and 2.8" upper with a ported Eaton. The front bearing looked great and measured like all the others when I rebuilt it due to piston issues. The crank went back in with a polish and standard size bearings, and all the bearing clearances were perfect. It has now lived another four years with a 2# lower and 3.5" upper with a KB 2. 8H making over 22 lbs. of boost. I think it is the larger blowers in the 3.4L + range that put unmanageable stress on uncaged lowers. Those seems to be the ones I have read about breaking snouts over the past 10 or so years in the forums.

 

[stangfreak]

a lower pulley on a eaton is 100% safe. You will have zero problems. we have been running lower pulleys on eatons for years and years and beating the crap out of the cars. The only time I have seen a problem with a aftermarket lower pulley is when people start running a 3.4L or bigger supercharger and a aftermarket belt tensioner.

 

[Notsoslowbowtie]

a lower pulley on a eaton is 100% safe. You will have zero problems. we have been running lower pulleys on eatons for years and years and beating the crap out of the cars. The only time I have seen a problem with a aftermarket lower pulley is when people start running a 3.4L or bigger supercharger and a aftermarket belt tensioner.

So your saying a 3.3 Lysholm is clear for take off! Haha j/k I'm contemplating getting a lower on my ported eaton but still running stock heat exchanger.