Wiped mains

[Schiada76]

Just tore the blower motor down.
#1 wiped extreme with material hanging out the sides
#2 no copper showing slight pitting
#3 same as #2
#4 spun
#5 wiped
Could too tight of a belt cause this?
Do you need to set kevlar belts looser, tighter or the same as a standard belt?
It's a 500CI BBC Mark IV running 11 to 12 #'s boost.

[steelcomp]

what were your clearances?

[wsuwrhr]

sounds like too tight of clearances, low oil pressure or loss of oil pressure.
Brian
I have no experience with a blower motor.

[Infomaniac]

Yea what they said. Did you "set" the rear main? end clearance?

[Fiat48]

Blower belts should all have about 3/4 inch of play in them regardless of material the belt is made out of. That is when the engine is hot. You don't want that belt pulling on the crank. If it's too loose then it can walk over a tooth (1/2" & 8mm) and bend the crank. Always have to keep an eye on the belt tightness between hot and cold.
Check the crank for straightness. Generally too tight a belt works on #2 main bearing.
As to what happened could be a world of things. This is how BBC die...by the mains. And usually spin #4.
Bent or cracked crank.
Line hone was never straight to begin with.
Not enough clearance. At least .003 and I like looser for flexy cranks.
Too much HP for the strength of the crank (crank flex)
Oil intersection holes not completly drilled through (I have seen that).
Any other oil pressure problem. When the oil wedge is lost for whatever reason then contact occurs. When that happens even for a millisecond the crank grabs that bearing and the bearing shrinks around the crank. Game over.
Just to sum it up..you can get away with a lot till the blower goes on.

[78Eliminator]

Brad, what crank was in there?

[Kurtis500]

Sounds like tight clearances. I run 35 clearances on the rods and mains, 40 wt oil and have 5 years on the bearings with over 150 passes. Looser clearances and heavy oil with a blower motor IMO is the way to go.
Check your oil pressure, you may be dropping it when you dont notice. In the BBC we had a loose pick-up cause the oil pressure to swing up and down a couple times. I thought it was the sending unit so we ran it again. Spun all but one bearing right off the trailer. :hammerhea

[Fiat48]

If it's blown and especially alcohol....I will fight like Hell for .0035 to .004. Been known to run .0045.

[Schiada76]

It was running fine for two years so I had to "fix" it. :D
Was running 5-6#'s boost so I put a chiller on it and ran the boost up to 11-12#'s. I knew I was on borrowed time at that point.
I can't remember the clearances when I assembled it last time but I followed the advice of George at Clay Smith. Still could have been some "assembler" error.
Oil pressure was always fine until it went away, rather quickly, one day.
I'm using the scat crank but will be stepping up if there is a problem with it.
If the clearances are too tight how long for the bearings to go away?
RE the 3/4" clearance when hot belt was definitely too tight, had 3/4" to 1" when cold.
Info, what do mean by "set" the rear main clearance? End play was checked.
Rod bearings are fine, a little pitting from some main bearing material.
I'll be taking it to Big Pete for a full analysis and machining.
Hell it's only money!
Oh yeah, It's getting a hat on this go 'round too. :D

[cdog]

It was running fine for two years so I had to "fix" it. :D
Was running 5-6#'s boost so I put a chiller on it and ran the boost up to 11-12#'s. I knew I was on borrowed time at that point.
I can't remember the clearances when I assembled it last time but I followed the advice of George at Clay Smith. Still could have been some "assembler" error.
Oil pressure was always fine until it went away, rather quickly, one day.
I'm using the scat crank but will be stepping up if there is a problem with it.
If the clearances are too tight how long for the bearings to go away?
RE the 3/4" clearance when hot belt was definitely too tight, had 3/4" to 1" when cold.
Info, what do mean by "set" the rear main clearance? End play was checked.
Rod bearings are fine, a little pitting from some main bearing material.
I'll be taking it to Big Pete for a full analysis and machining.
Hell it's only money!
Oh yeah, It's getting a hat on this go 'round too. :D
Brad, My engine builder says that the scat cranks are china forged and need more machining before you put them in an engine. He had me buy a new dragon slayer Callies crank for when I step up to a procharger or TT's. I had a simular experiance with my eagle crank. It was'nt bent. Just needed more machine work done to it. He says that a factory GM crank is stronger than all of the china forged cranks. Especially on blower, crank pulley applications. I'd step up to a better crank. Good Luck.

[Infomaniac]

Setting the rear main bearing is torquing all the caps but the rear main. With the rear main snug I smack the crank fwd then back. I pry the crank fwd when torquing the rear main.
This sets the rear main bearing. If your end play was checked then it was probably OK.
You would be surprised how many folks just put them together without attention to the rear main.

[Schiada76]

Setting the rear main bearing is torquing all the caps but the rear main. With the rear main snug I smack the crank fwd then back. I pry the crank fwd when torquing the rear main.
This sets the rear main bearing. If your end play was checked then it was probably OK.
You would be surprised how many folks just put them together without attention to the rear main.
Yup, did that. No smack though, just prybar.

[Schiada76]

Brad, My engine builder says that the scat cranks are china forged and need more machining before you put them in an engine. He had me buy a new dragon slayer Callies crank for when I step up to a procharger or TT's. I had a simular experiance with my eagle crank. It was'nt bent. Just needed more machine work done to it. He says that a factory GM crank is stronger than all of the china forged cranks. Especially on blower, crank pulley applications. I'd step up to a better crank. Good Luck.
There's been a lot of back and forth on that. Doesn't Scat finsh their cranks onshore?

[Schiada76]

Another slight problem though.
Dampner stuck. Cranked like hell on the puller, tried heating dampner, tried imact wrench on dampner, heat, impact, heat impact. No worky.
Did remember to use anti seize on install. Key looks ok but last machinist talked me out of two keys on the crank. What are the odds it walked over the key a little and how do I get the MF off?
Haven't yet tried 3/4" breaker bar with a long ass cheater. :D

[cdog]

Another slight problem though.
Dampner stuck. Cranked like hell on the puller, tried heating dampner, tried imact wrench on dampner, heat, impact, heat impact. No worky.
Did remember to use anti seize on install. Key looks ok but last machinist talked me out of two keys on the crank. What are the odds it walked over the key a little and how do I get the MF off?
Haven't yet tried 3/4" breaker bar with a long ass cheater. :D
You might have twisted the snout and key way??? It is common on blower engines with red cranks. That's where they have the most problems with them because of the weak forgings. Fonse has had them fail and refuses to use the china cranks.

[Infomaniac]

What kind of puller do you have?
ALWAYS double key them when turning a roots blower.

[Schiada76]

Craftsman puller
J540 said to try spraying C02 on the crank while heating the dampner with the puller torqued down.
This oughta be interesting.

[79 HUSTLER]

[QUOTE=BradP]
J540 said
QUOTE]
:hammerhea :hammerhea :hammerhea This can't be good....

[Schiada76]

I told him to come over and crank on the puller but he came up with some BS story about shoulder surgery blah blah blah. :D :D

[Moneypitt]

Brad, I have 2 homemade pullers from hell for BBC. Solid steel, 1 1/2" thick. I think it will get your balancer off. I can bring it down, or meet you 1/2 way or something. I DO still owe you a drink or 2...........Ray

[Schiada76]

Thanks Ray.
Check your pm's

[79 HUSTLER]

I told him to come over and crank on the puller but he came up with some BS story about shoulder surgery blah blah blah. :D :D
Thats what happens when you always jerk away with the same hand hour after hour. :eek: :eek:
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j-540 your a fffaaaaaaagggggggg........ :2purples:

[Moneypitt]

No PM Brad?.............Ray

[Schiada76]

HMMMM I sent a reply to yours.
Anyway, I got your # and will call you this week when I can figure a time to meet with you to borrow your puller.. I'm going fishing Saturday so would during the week be OK? I'm going to try 540's method just to see if it works too. :D

[lucky]

brad ==== bigger hammer :D

[Schiada76]

Just talked to Pete and he said to just leave it on and he'l pull it so I won't be needing your puller Ray.
Thanks though!

[cyclone]

Another slight problem though.
Dampner stuck. Cranked like hell on the puller, tried heating dampner, tried imact wrench on dampner, heat, impact, heat impact. No worky.
Did remember to use anti seize on install. Key looks ok but last machinist talked me out of two keys on the crank. What are the odds it walked over the key a little and how do I get the MF off?
Haven't yet tried 3/4" breaker bar with a long ass cheater. :D
Detonation will commonly make the dampner hard to remove. when the engine detonates the balancer will chatter on the snout and etch into the material. My last blower motor was detonating and I didnt know it. the balancer was a bitch to remove. broke two pullers before it finally came off and it had anti-sieze on the snout when i originally installed it.

[Schiada76]

Don't think I was detonating. Plugs and pisons look great.

[Schiada76]

Tried J540's method of dampner removal, no good. Did break the Craftsman puller with the long ass cheater. The Mac puller did work however. :D
Off to the builder this week for full review.

[Condor]

More boost = More heat !
Drag racers can get by with more, because of the short WOT time.
Sounds like an oil problem with the added heat created by the additional Boost.
You didn't say how long of a pass you were making ?
If you're running a pan that's less than 8 inches deep w/o a windage tray it's easy to have Cavitation around the oil pick-up.
I replaced the Mains and bought a couple Line Bores figuring that out ! The bigger the stroke the bigger the problem.
Long living BBC's with big boost running for long distances all use Dry Sumps.
If you're Blasting across the Lake at high RPM's and you're oil pressure starts to come down, it's a good indication you are having Cavitation problems. A lot of people think that the oil is all in the top-end and it could be, but it could be cavition.
You didn't say, if you have an Oil Temp gauge or an oil cooler ? :squiggle:

[Schiada76]

Mondo oil cooler, temp gauge not over 250 (short time).
Milodon 10qt pan with tray and baffles