Bellhousing runout '65 273

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Bob Jasinski

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The original 273 from my '65 Barracuda Formula S is now rebuilt and ready for pickup, but have run into an issue I need input on. This was an automatic that I have converted to a 4 speed using all factory parts including the proper bellhousing found at a swap meet. The machinist did the necessary work on the crank and installed the pilot bushing. I brought him the bellhousing and asked that he check it for runout. He did, and told me it is .017" out, and he feels its OK using it that way. I'm concerned and told him I would look into it further, and the factory manual says maximum runout is .008", so I think it should be corrected to alleviate potential problems later on. Am I correct in being concerned? Where can I find the offset bellhousing dowels to fix the problem?
 
Pretty sure it is bore runout, but I did just send him an email to confirm.
 
The more I think about it, the less inclined I am to use it the way it is, I'm a bit surprised the machinist suggested it would be OK. Just hope this isn't an indication of other tolerances that were "good enough". He has had the engine for about 8 months and seems to be pretty knowledgeable and thorough in his work though. I'm definitely going to do what is necessary to get it right, it would be foolish not to, I'm in no big hurry and I want it the best it can be. I remembered I bought a dial indicator with magnetic base back in the late '90s and just now found it. Looks like Summit probably has the offset dowels I need, I just need to confirm the diameter.
 
Yeah, 8 months. Originally told me 3 months, but I've had issues with the body shop, so the whole project is out a about a year longer so I didn't bug him too much.
 
.017 isnt that bad IMO. I've seen them 3x that in cars with problems. But - if it's apart I'd do it. The $50 and couple hours maybe will give better performance and peace of mind.
 
I need some help understanding the FSM on correcting the bellhousing runout using offset dowels. The FSM example covers runout at .020" measured with the dial indicator, but then states, "in this case, the housing is off crankshaft centerline .010". How is that? If the runout is .020", how can the crank be off .010" when you just measured .020"? The drawing then shows the offset pins installed opposite the runout, which makes sense, but how would a .007" offset make up for the .020" you just measured?

2nd question, is it easy to remove the factory dowel pins from the block, do they just knock out with a punch? Since I have the dial indicator, I'd like to install the offset dowels myself, but would hate to get the engine back here only to find out the dowels take a special tool to remove them, if that's the case maybe I should just have the machinist R & R the dowels. Thoughts please.
 
.010 off center will read .020 Total Indicator Runout (TIR). The dowels can be removed. I use a brass punch. If you get .007 in the correct position you would only have .006 TIR. close enough.
 
I need some help understanding the FSM on correcting the bellhousing runout using offset dowels. The FSM example covers runout at .020" measured with the dial indicator, but then states, "in this case, the housing is off crankshaft centerline .010". How is that? If the runout is .020", how can the crank be off .010" when you just measured .020"? The drawing then shows the offset pins installed opposite the runout, which makes sense, but how would a .007" offset make up for the .020" you just measured?

2nd question, is it easy to remove the factory dowel pins from the block, do they just knock out with a punch? Since I have the dial indicator, I'd like to install the offset dowels myself, but would hate to get the engine back here only to find out the dowels take a special tool to remove them, if that's the case maybe I should just have the machinist R & R the dowels. Thoughts please.
Assume that you have an indicator mounted, and the bellhousing is perfect, no runout. Now move the bell housing .005 . Your indicator will read .005 less on the short side, and .005 more on the long side. Measured runout.... .010.
 
So, runout is not the distance from the center out, it is the sum of both dimensions, (run in and run out) is that right? I always thought runout was just that, the difference between the center and how much "runout" there is from that center point.
 
Torque the bell to spec when testing.

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Check the bell trans face as well.
 
Thank you all, learned something new today. My dial indicator mount is a magnetic type, was thinking I would stick it on the flywheel like the FSM states. I can't find the thickness specs for the flywheel in the FSM, but I have two good used stock 122 tooth flywheels here, one measures .895" and the other .879". Planned on using the thicker one, but both look very good. Anybody know the thickness spec?
 
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I would be much more concerned with the clutch face area than with thickness. Is it smooth, heat checked, small cracks, hard spots etc.
 
In my experience, those .500 dowels are for a Chev, they would not fit in my block. The good old mopar performance ones that i used fit perfect and they measure at .497. Those dowels from mopar performance are in my treasured special parts drawer.

That's good advice, I was wondering if the Summit .5" were exactly .5" Doesn't sound like they would fit if the hole is .5". .497" makes sense.
 
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The more I think about it, the less inclined I am to use it the way it is, I'm a bit surprised the machinist suggested it would be OK. Just hope this isn't an indication of other tolerances that were "good enough". He has had the engine for about 8 months and seems to be pretty knowledgeable and thorough in his work though. I'm definitely going to do what is necessary to get it right, it would be foolish not to, I'm in no big hurry and I want it the best it can be. I remembered I bought a dial indicator with magnetic base back in the late '90s and just now found it. Looks like Summit probably has the offset dowels I need, I just need to confirm the diameter.
I have to agree with him... If it's only .008 out as is, and that "is ok" as per spec.
 
I have to agree with him... If it's only .008 out as is, and that "is ok" as per spec.

eekvonzipper, You need to read post#17. I thought the same thing, and didn't understand why the FSM (factory shop manual) said to divide the runout by two. The total runout spec is .008. That means .004 plus .004 max. the runout is not measured from the centerline of the crank but the total variance of movement, left to right, as the crank is turned 360 degrees. My bellhousing is out .017 total, exceeding the .008 by more than double.
 
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