[Gmecm] Bellhousing Design-Iron Duke

Fri Feb 17 17:43:36 UTC 2006

The dowel pins match for both engines so I would take
a thin piece of cardboard that is larger than the
bellhousing pattern, cut the holes for the dowl pins
and sandwich it between, I BELIEVE the lower bolt
holes a are also the same, otherwise use some bolts
and fender washers, c-clamps or whatever, the idea is
to transfer an image of both parts into the cardboad,
and you now have a pattern

The adapter holes dont have to be perfect as long as
the dowl pins from the motor are fully engaged in the
transmission, even if that requires making longer
pins.  The bolts just hold it together.  Dustin Lof

--- "Jason M." <galaxiecustom500 at sbcglobal.net> wrote:

> Well In my case I had planned to make one until
> finding the cheap TCI 
> adapter, at the time it was only an hour drive to
> summit racing to pick it 
> up.  Lucked out and got a $140 K&N Xstream air
> filter assembly out of the 
> scratch and dent bin for $50.  Someone simply
> returned it without the 
> package or hold down stud.
> 
> As for actually making one, There are several ways
> to go about it.  I have a 
> book with a dimensioned drawing of a small block
> Chevy.  Forget if I found a 
> dimensioned drawing of an Oldsmobile block.
> 
> Once you have both of those drawings it will be
> simple geometry to set up 
> the coordinates of each hole then put it on a mill. 
> The mill I have access 
> to is not for personnel use but they sort of look
> the other way if you go in 
> when nobody needs it and use your own tooling.
> 
> Then in a not so easy way you can put a straight
> edge at the bottom of your 
> part, then use a square to draw out the locations
> then carefully drill out 
> on a drill press or by hand.
> 
> There is a third option that requires the least
> amount of 
> measuring/dimensioned drawing.  Use transfer
> punches.  They are specifically 
> made for doings stuff like this.  They are a round
> cylinder with a small 
> cone tip.  Set the transmission on it's front
> flange, on top of the metal 
> for the adapter.  Find a transfer punch that just
> fits inside the hole, then 
> smack it with a hammer.  This would work best if you
> have a Chevy and a BOP 
> transmission setting there.  After the first one's
> pattern is transferred 
> drill out the holes and install dowel pins in the
> adapter to align the 
> second.
> 
> Another way you could align it is to maybe put a
> piece of pipe that just 
> fits over the input shaft of the transmission onto
> the adapter plate, weld 
> it down.  As long as it's ridged and lets the bell
> housing flange rest flush 
> you'll know the input shafts are centered.  Then
> using a straight edge along 
> the plate you can measure to a pair of bolt holes,
> one on each side.  When 
> the measurement is the same side to side then you
> know the bell housing 
> pattern is parallel to the straight edge
> 
> However the most important part in all this is to
> make sure you have good 
> steel stock with dimensional variance +-0.001  over
> it's surface.  When 
> looking into making my own I found the material
> would cost between $15-$20. 
> Then there is a great deal of time spent measuring. 
> At the time it was 
> averaging between 5-10 degrees F outside, and I
> didn't have much free time. 
> So the price of a Pre made adapter was just fine for
> me.  Was already 
> mentioned by another it was $58, I remember it being
> cheaper but don't feel 
> like digging out the receipt to check.
> 
> I also found a company that made a really nice 1/2''
> aluminum adapter for 
> around $150 as I remember.  Could even get them as a
> large rectangle to use 
> as a "motor" plate.  They actually came with inserts
> for the crank to center 
> the torque converter.  Which makes it more of a
> straight bolt in, then 
> having to rotate the engine several times while
> snugging down the torque 
> converter screws.
> 
> I'm possibly going to buy one of the nice aluminum
> adapters or make one for 
> the 500 Cadillac going into a caprice.  Will
> probably end up buying one 
> since this is a common adapter and not looking like
> I'll have much free time 
> this summer.  Have to do the body work and paint the
> '85 caprice, mock up 
> the drivetrain, rebuild the engine, build accessory
> drive brackets, rebuild 
> a SBC to put in my beater car in place of the worn
> out 350 olds. Back half 
> an olds omega for a friend, and I'm sure some other
> stuff will come up.
> 
> Almost forgot, if you don't have a dimensioned
> drawing, you might get away 
> with using a tape measure but it would be so much
> easier and precise to use 
> dial calipers.  Basically just measure everything. 
> Since this application 
> shares the dowel pins you don't need to worry about
> centering to the input 
> shaft while measuring.
> 
> BTW, things don't need to be perfect, when I was
> reading about doing this 
> think the guideline I found was to be within 0.010''
>  For an automatic there 
> is some "wiggle room" with the TC splines, and the
> flexplate got that name 
> for a reason, it was designed to flex so production
> line variance in parts 
> didn't have to be so tight.
> 
> I've pretty much have gone on long enough, my advice
> though would just be to 
> buy one for $50, unless you can spare the time.  Now
> if you had some kind of 
> odd combination where the adapter cost $300 +(ford
> FE to GM 700r4) or an 
> application nobody makes, like some tractor
> transaxle to... maybe some early 
> 1900's straight 8, most American v8's are covered
> into most tractors.  Think 
> you get my point.
> 
> Now if you already own a mill... and have drawings,
> or your mill is tall 
> enough to fit a transmission case or engine block in
> it.  You could machine 
> an adapter in an afternoon easy.  Key is it needs to
> have instrumentation on 
> it.
> 
> btw, If we are able to send pictures to the list now
> I could send out 
> pictures of the adapter installed on the engine,
> also with a transmission on 
> it.
> ----- Original Message ----- 
> From: "Burntkat at sc.rr.com" <burntkat at sc.rr.com>
> To: <gmecm at diy-efi.org>
> Sent: Friday, February 17, 2006 7:51 AM
> Subject: RE: [Gmecm] Bellhousing Design-Iron Duke
> 
> 
> How would you go about making an adapter-- in other
> words-- how would you
> measure the holes from center of the shafts with
> enough accuracy to ensure
> proper alignment of torque converter and flexplate?
> 
> Great thread, and I'll need the info for adapting a
> BOP pattern 5.7 diesel
> to my 700R4...
> 
> 
> 
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> 

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