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Bellhousing run-out / offset dowel pins
#1142488
12/23/11 02:44 PM
12/23/11 02:44 PM
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Joined: Jul 2003
Posts: 1,212
Canton, Ohio
Crazy68Dart
OP
pro stock
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OP
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Joined: Jul 2003
Posts: 1,212
Canton, Ohio
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I removed two bolts from the flywheel and got the mag base positioned. Indicator is setup, doing a full sweep around made sure it was making contact the whole way. Through the sweep found the point that had the lowest indicator value in the circle and zeroed the indicator. This roughly 8 o-clock. Then did three sweeps (to make sure I could reproduce the value) and found at 2 o-clock the dial to read 22 thousandths which is my highest reading. Splitting this will give me 11 thousands total run-out. Is this method correct? What is max tolerance that I should shoot for? Also, when ordering offset dowel pins... do I order them per the final number, 11 thousandths, or per the 22 thousandths value? I assume the final value so I would order the .007 kit, correct? This would then give me total of .004 run-out. http://www.robbmcperformance.com/products/dowels.htmlThanks.
383, Hemi 4-Speed, AlterKtion, D60
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Re: Bellhousing run-out / offset dowel pins
[Re: astjp2]
#1142490
12/23/11 03:37 PM
12/23/11 03:37 PM
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Joined: Jul 2003
Posts: 1,212
Canton, Ohio
Crazy68Dart
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pro stock
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Canton, Ohio
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Seriously, less than .003? I would think there is at least that much in the pilot bushing.
I could achieve .003 with the .014 dowel.
Oh and... this is an 18 spline 833, nothing fancy.
Last edited by Crazy68Dart; 12/23/11 03:38 PM.
383, Hemi 4-Speed, AlterKtion, D60
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Re: Bellhousing run-out / offset dowel pins
[Re: radar]
#1142492
12/23/11 04:49 PM
12/23/11 04:49 PM
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Joined: Jan 2003
Posts: 75,095
A Banana Republic near you.
JohnRR
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Quote:
There's 5 thou wiggle room from the pins to the bell holes stock anyway, I think that's the factory spec- within 5 thousandths of perfect.
There is ??? I've never had a factory bellhousing on factory dowels and had 5 thou of wiggle room, if you have a bellhousing wit h5thou of wiggle it's time to replace the bell , dowels or both ..
5 thou wiggle ...  ...
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Re: Bellhousing run-out / offset dowel pins
[Re: JohnRR]
#1142493
12/23/11 05:16 PM
12/23/11 05:16 PM
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Joined: Jan 2003
Posts: 26,000
Rio Linda, CA
John_Kunkel
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Rio Linda, CA
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Quote:
Quote:
There's 5 thou wiggle room from the pins to the bell holes stock anyway, I think that's the factory spec- within 5 thousandths of perfect.
There is ??? I've never had a factory bellhousing on factory dowels and had 5 thou of wiggle room, if you have a bellhousing with 5 thou of wiggle it's time to replace the bell , dowels or both .
The dowels are .496 and the hole in the housing is .500 +- .001 so, if both dowels are dead center in their housing holes, you could have that much slop. In the real world, the slightly larger housing holes are to compensate for production tolerances and the dowels will more likely be off center in their holes.
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Re: Bellhousing run-out / offset dowel pins
[Re: John_Kunkel]
#1142494
12/24/11 09:21 AM
12/24/11 09:21 AM
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Joined: Jul 2003
Posts: 1,212
Canton, Ohio
Crazy68Dart
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pro stock
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Canton, Ohio
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This is why .003 seems like such a crazy value to "warranty" something after. Either way, I ordered the .014, so this will give me .003. I probably could have ran with .011 and never saw a problem, but now I know the value is pretty tight and one less thing to worry about if I have other issues. 
383, Hemi 4-Speed, AlterKtion, D60
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Re: Bellhousing run-out / offset dowel pins
[Re: Crazy68Dart]
#1142495
12/24/11 11:37 AM
12/24/11 11:37 AM
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Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
70Cuda383
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Marysville, O-H-I-O
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Quote:
This is why .003 seems like such a crazy value to "warranty" something after.
Either way, I ordered the .014, so this will give me .003. I probably could have ran with .011 and never saw a problem, but now I know the value is pretty tight and one less thing to worry about if I have other issues.
My Lakewood bell said spec is .005 not .003. Which is why the dowels are .004, .011, etc so that no matter how much your off, you can get it back to less than .005
**Photobucket sucks**
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Re: Bellhousing run-out / offset dowel pins
[Re: John_Kunkel]
#1142496
12/24/11 12:15 PM
12/24/11 12:15 PM
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Joined: Jan 2003
Posts: 75,095
A Banana Republic near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,095
A Banana Republic near you.
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Quote:
Quote:
Quote:
There's 5 thou wiggle room from the pins to the bell holes stock anyway, I think that's the factory spec- within 5 thousandths of perfect.
There is ??? I've never had a factory bellhousing on factory dowels and had 5 thou of wiggle room, if you have a bellhousing with 5 thou of wiggle it's time to replace the bell , dowels or both .
The dowels are .496 and the hole in the housing is .500 +- .001 so, if both dowels are dead center in their housing holes, you could have that much slop. In the real world, the slightly larger housing holes are to compensate for production tolerances and the dowels will more likely be off center in their holes.
You are right John, I didn't think that thru before pop pooing the amount of slop, then you add in more potential offset when you install a bellhousing from one block onto another.
I had to make a set of dowels for a 440 because you can't buy straight .496 pins and the auto trans I put on it went on with no movement that I could feel , not idea though how far it would be out ...
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Re: Bellhousing run-out / offset dowel pins
[Re: astjp2]
#1142498
12/24/11 05:06 PM
12/24/11 05:06 PM
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Joined: Jul 2003
Posts: 1,212
Canton, Ohio
Crazy68Dart
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So, getting the old dowel pins out, pair of vise grips is chewing them up pretty good. They are turning, but just barely. I am guessing the best way to do this is with acetylene and get things real hot? I don't have a set of torches which could be a problem. 
383, Hemi 4-Speed, AlterKtion, D60
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Re: Bellhousing run-out / offset dowel pins
[Re: ahy]
#1142500
12/24/11 05:59 PM
12/24/11 05:59 PM
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Joined: Jul 2003
Posts: 1,212
Canton, Ohio
Crazy68Dart
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Think I might go the drill/tap route. I can spin it with vise grips, but cannot get any outward force on them without popping the vise grips off.
383, Hemi 4-Speed, AlterKtion, D60
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Re: Bellhousing run-out / offset dowel pins
[Re: Crazy68Dart]
#1142501
12/24/11 06:19 PM
12/24/11 06:19 PM
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Joined: Mar 2007
Posts: 3,287
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,287
West Coast, USA
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Just a quick mention here that aligning the bellhousing bore is only half the battle.
You also need to ensure that the face of the bellhousing is parallel to the flywheel/block face. I had to use shims next to the block mounting bolts to get mine parallel before using the offset dowels to get the bore lined up.
Once it was parallel and the bore was lined up with the dowels, I drilled two small 1/8 inch pilot holes on either side of the bellhousing and slightly into the block. Then I drove in small, interference fitting metal dowels to help hold the positioning.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: Bellhousing run-out / offset dowel pins
[Re: Crazy68Dart]
#1142502
12/24/11 06:23 PM
12/24/11 06:23 PM
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Joined: Mar 2007
Posts: 3,287
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,287
West Coast, USA
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Quote:
Think I might go the drill/tap route. I can spin it with vise grips, but cannot get any outward force on them without popping the vise grips off.
I've had to drill them out almost all the way to the size of the dowel before caving in on side of the dowel with a hammer & chisle. Sometimes they come out on the drill. Just be careful not to go into the block, or crack the block around the hole.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: Bellhousing run-out / offset dowel pins
[Re: Crazy68Dart]
#1142503
12/24/11 07:42 PM
12/24/11 07:42 PM
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Joined: Jan 2003
Posts: 26,000
Rio Linda, CA
John_Kunkel
Too Many Posts
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Rio Linda, CA
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Drill/tap for a slide hammer or for a zerk fitting, a grease gun has enough poop to push the dowels out.
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Re: Bellhousing run-out / offset dowel pins
[Re: astjp2]
#1142504
12/26/11 02:33 AM
12/26/11 02:33 AM
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Joined: Jan 2003
Posts: 75,095
A Banana Republic near you.
JohnRR
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Posts: 75,095
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Quote:
Dont forget that the bellhousing was line bored with the block at the factory. They were matched pairs...and dead nuts on...Tim 
They would only be like that assuming that once the bellhousing was bolted on the bolts were NEVER loosen for any reason , not that I can think of one now , ever. Once you loosen the bolts all bets are off ...
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Re: Bellhousing run-out / offset dowel pins
[Re: astjp2]
#1142505
12/26/11 01:09 PM
12/26/11 01:09 PM
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Joined: Jan 2003
Posts: 18,427
UPPER MICHIGAN, MARQUETTE COUN...
NITROUSN
I Live Here
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I Live Here
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Posts: 18,427
UPPER MICHIGAN, MARQUETTE COUN...
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Quote:
Dont forget that the bellhousing was line bored with the block at the factory. They were matched pairs...and dead nuts on...Tim
I never heard that story. I highly doubt that they did it that way.
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Re: Bellhousing run-out / offset dowel pins
[Re: NITROUSN]
#1142506
12/26/11 01:13 PM
12/26/11 01:13 PM
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Joined: Jan 2003
Posts: 75,095
A Banana Republic near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,095
A Banana Republic near you.
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Quote:
Quote:
Dont forget that the bellhousing was line bored with the block at the factory. They were matched pairs...and dead nuts on...Tim
I never heard that story. I highly doubt that they did it that way.
There is a picture of the engine assembly line showing engine blocks with no rotating assemblies installed yet with bellhousing bolted to them.
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