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Discussion Starter #1
is it always needed or is there a h.p. amount or % of boost when it has to be done? :confused:
 

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I do one single 1/4" keyway on everything I have ever built. Never a problem.
Some guys cut the 1/4" key slot right over the existing key slot. Others go 180 degrees from that and cut for a single 1/4 key.
 

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steelcomp was here
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I do one single 1/4" keyway on everything I have ever built. Never a problem.
Some guys cut the 1/4" key slot right over the existing key slot. Others go 180 degrees from that and cut for a single 1/4 key.
Fiat...so you say a single 1/4" keyway is enough, or you add a single 1/4" keyway and still use the stock one? What you posted above sounds like both. I'm cornfuzed.


For what it's worth, I have 7" Romac steel SFI balancers with double keyways availablbe.
 

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Discussion Starter #4
i bought a dc 8-71 blower and now am finally getting around to building the engine i brought the pulley to the shop to get everything balanced and there is only one keyway. so it sounds like i will be all right then. do i make the keyway 1/4" or is it that size already? its on a bbc
 

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BBC has 3/16 stock.

I always cut 1/4 key opposite the stock key.

But... not my own stuff, it's going to a customer and the extra cannot hurt.

Some stuff comes with 2 1/4 keys and you have no choice but to do something.
 

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steelcomp was here
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BBC has 3/16 stock.

I always cut 1/4 key opposite the stock key.

But... not my own stuff, it's going to a customer and the extra cannot hurt.

Some stuff comes with 2 1/4 keys and you have no choice but to do something.
Cutting a keyway is half of it...do you broach the hubs or balancers too, or do most of what you use already come with 1/4" slots?
I don't know about you guys, but getting two keyways to line up correctly is a PITA.
 

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I mean single key is enough. Tho it is easier( because it is easier to locate the mill) and just go over the 3/16 and make it 1/4....I prefer to do it 180 from that. So I just run one single 1/4" and forget about the stocker 3/16 key.

Blower hubs are either broached already with one single 1/4 key.....or 2 1/4 keys....or one 1/4 and one 3/16. And a lot of times.....the ones with 2 keys are not dead on 180 apart. So...hence I just do 1 key.
 

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Discussion Starter #8
well thanks for the information as always its a great help to me when building these dam engines on my own. i will call the machine shop in the a.m. and have them check the hub to see what size it is and to tell him to do the 1/4" on it. just hope my hub is 1/4" or like every other time have to buy another one and add another part to the pile. :)hammers
 

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We can broach the balancer and key the crank. You can customize the broach to line up perfectly and an indexing head on the mill for the crank.

Same indexing head we use to put a new bolt circle in wheels. Well not the same one, we have 3. The one for wheels has been modified a bit to accomodate wome wheels.

Find the center of the existing key and rotate 180.

Make a stepped key if you have a stock crank and aftermarket balancer 1/4 keyed.
 

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i bought a dc 8-71 blower and now am finally getting around to building the engine i brought the pulley to the shop to get everything balanced and there is only one keyway. so it sounds like i will be all right then. do i make the keyway 1/4" or is it that size already? its on a bbc
If it's a blower hub...and one keyway....I am sure it is 1/4". You do know that there is a different "hub" that is sold for external balance...if you are using an external balance crank. The hub has a counterweight on it.
I have a couple of them here if you need.
 

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Yea if you have an external balance hub with a counterweight, and there are 2 1/4 keys. The counterweight on the hub lines up with the counterweight on the crank.
 

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LOL. Yeah.

One time I built a guy an external balance blown gas deal for a street rod. Was a year later before I happened to catch the guy at the Hot August night deal here.
I asked him how the motor was doing and he said it was a little "too wild" so he and his buddy changed the camshaft to a hydraulic roller deal.
So he fires it up and I notice a lot of "shakin goin on" in the fenders....especially for a blown deal.

Sure enough....he put the external hub on 180 out. It ran a year that way.
 

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LOL. Yeah.

One time I built a guy an external balance blown gas deal for a street rod. Was a year later before I happened to catch the guy at the Hot August night deal here.
I asked him how the motor was doing and he said it was a little "too wild" so he and his buddy changed the camshaft to a hydraulic roller deal.
So he fires it up and I notice a lot of "shakin goin on" in the fenders....especially for a blown deal.

Sure enough....he put the external hub on 180 out. It ran a year that way.

Boater would not have done that. LOL He should have just flipped his bearings and ran it for another year.
 

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LOL.
Yeah..this guy thought all was normal. Never had a clue. Thought the shakin was cool.
So did the guy at the drags who ran an external balance flexplate on a 427. Wondered why his fenders were always missing bolts. :D
 

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LOL.
Yeah..this guy thought all was normal. Never had a clue. Thought the shakin was cool.
So did the guy at the drags who ran an external balance flexplate on a 427. Wondered why his fenders were always missing bolts. :D
LOL yea he thought he had a v-drive.

But when bolts were missing they would not show up in the bilge a week later. To be instantly identified by the owner as to where they go.

I have never lost anything off my boat or engine and it actually left the boat. I have been known to say we'll find it eventually. Most of the time a week later look down and there it is.
:)hand
 

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Not me. Fact they joke about finding parts of my boat in the lake out here. Last thing I lost was the entire left side fuel tank filler...cap and all. They found it with a metal detector...guy even brought it over. "Knew it had to be yours." LOL.

But I do like to throw a couple 3/8" bolts on the floor of Morg's boat...then watch as he tries to figure out where they came from. Keeps him busy. :D
 

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This thread is oficially hijjacked.

Worst one for me was the key and floatie thing. Had to start it in gear with a screwdriver to get back. Luckily was running a mag. And Starter on the driver's side within reach LOL

Found it the next week between the seats in the bilge. Same place everything else shows up. Even the tall breather cap off the valve covers. 3 times now lost one and I have no idea how it lands in the boat. Bolts and all.
 

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Actually not a hijack but rather a planned deal by me to get Slotracer so discouraged in building a blown motor that he will then sell me (cheap of course) that Cole Tr-1 1/2(as I call it) with the Lange bottom so I can see how much difference the bottom work did. :)grn
 

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Discussion Starter #19
well i am not ready to sell yet. the hub i have has is shaped with what looks like a counterweight on it. its not all the way around. the guy doing the machine work has built quite a few blown engines for alot of people that drag race. he has 3 or 4 engines that are running at sacramento raceway on tuesday for the new year day races. he has built engines for russio's in so. city. on the highjack side of things.

But I do like to throw a couple 3/8" bolts on the floor of Morg's boat...then watch as he tries to figure out where they came from. Keeps him busy. this is just plain mean to watch someone look for the missing bolts
 
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