Topic: Bellhousing centering
in Forum: C3 Driveline Components
Already a Member?
Click Here to Login
Not yet a Member?
Click Here to Register for Free!
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20218
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Well, sorta...
There is a specific attachment that makes doing this a lot easier. Of course, I don't have one anymore.
Otherwise, it is just a matter of getting the magnetic base as close to the center of the crank pilot as possible, then setting the dial by turning the engine, taking the measurements at 4 points, then moving the dial to get it to an average at 90deg North/South-East/West.
If you have a machinist's rule, you can measure the opening in the bellhousing to find center, then center the dial off of that. If that makes any sense at all.
I will add this...in all my years of fooling with hot-rod/racers, etc., the only time I've ever actually needed to "center" a bellhousing was on aftermarket scattershields, most of which are stamped steel, and prone to be off just a wee bit...like 1/4"!!!
. On a stock, cast bellhousing, with a regular standard trans, the hole in the bell would have to be off by a great deal to create any issues with the trans not shifting properly, or causing pre-mature bearing/bushing wear. If the engine dowels are in good shape/new, and there is no wear on the dowel holes in the bell, I can't see needing to align it any better than Chevy did. If there is wear in bell holes, there is a repair for those, that bores out the worn hole, and then you put in a steel insert. I have done that on a few in the past...
Just my opinion.
Adams' Apple 2009-01-02 20:12:10
There is a specific attachment that makes doing this a lot easier. Of course, I don't have one anymore.
Otherwise, it is just a matter of getting the magnetic base as close to the center of the crank pilot as possible, then setting the dial by turning the engine, taking the measurements at 4 points, then moving the dial to get it to an average at 90deg North/South-East/West.
If you have a machinist's rule, you can measure the opening in the bellhousing to find center, then center the dial off of that. If that makes any sense at all.
I will add this...in all my years of fooling with hot-rod/racers, etc., the only time I've ever actually needed to "center" a bellhousing was on aftermarket scattershields, most of which are stamped steel, and prone to be off just a wee bit...like 1/4"!!!
. On a stock, cast bellhousing, with a regular standard trans, the hole in the bell would have to be off by a great deal to create any issues with the trans not shifting properly, or causing pre-mature bearing/bushing wear. If the engine dowels are in good shape/new, and there is no wear on the dowel holes in the bell, I can't see needing to align it any better than Chevy did. If there is wear in bell holes, there is a repair for those, that bores out the worn hole, and then you put in a steel insert. I have done that on a few in the past...
Just my opinion.
Joel Adams
C3VR Lifetime Member #56 
My Link 
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
SPONSOR AD:: (Our Sponsors help support C3VR)
Is you clutch installed? If so remove it. Take a piece of fine sandpaper and lightly run it around the bellhousing opening to remove any dirt or burr's.
Sarge81 2009-01-05 18:20:22
I just got the magnetic base affixed to the flywheel. It doesn't have to be dead center. Then line up the dial indicator with the pointer aimed at the 12 o' clock position and dial zero'ed out. With an assistant slowly turning the engine.. take measurements as soon as the dial moves. Record the reading at it's peak reading. Then continue on until the dial moves again and record. Once you made a complete revolution compare your readings.
If for example you have a reading of +.005" at the 3 o' clock position and then a reading of - .007" at the 9 o'clock position. Your offset is .012".
I did my measurements 4x's til I was satisfied. So be patient.
(Fixed math error)
TKO500 5 spd.
Borgeson Steering Box
Born 8/1981
Sequence #3975
Click here to see more pics of my Vette on CarDomain.
Lifetime Member #26
Lifetime MemberHot Springs, AR - USA
Joined: 4/24/2004
Posts: 3236
Vette(s): 69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans
clutch is off...i need to do some smoothing, i think i found a burr on the engine facing, the upper right side. and I need to remove some overspray on both engine and bellhousing.
Lifetime MemberHot Springs, AR - USA
Joined: 4/24/2004
Posts: 3236
Vette(s): 69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans
all done.. joel your gauge is in the mail tomorrow, I put some S&H in the box. Thanks again for the loaner.
everthing is documented here
if you looked at this before make sure you see the transmission and the alignment chart, if not, hit refresh.
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20218
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Glad ya got it figured out, Ben!
It all looks really nice! It's getting closer, eh?
It all looks really nice! It's getting closer, eh?
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
Lifetime MemberHot Springs, AR - USA
Joined: 4/24/2004
Posts: 3236
Vette(s): 69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans
my fever finally broke this morning
Been sick since 12/31
Wrenching while sick not a good idea
Suddenly brain started working again
Been sick since 12/31
Wrenching while sick not a good idea
Suddenly brain started working again
Lifetime MemberHot Springs, AR - USA
Joined: 4/24/2004
Posts: 3236
Vette(s): 69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans
[QUOTE=Sarge81]Is you clutch installed? If so remove it. Take a piece of fine sandpaper and lightly run it around the bellhousing opening to remove any dirt or burr's.
I just got the magnetic base affixed to the flywheel. It doesn't have to be dead center. Then line up the dial indicator with the pointer aimed at the 12 o' clock position and dial zero'ed out. With an assistant slowly turning the engine.. take measurements as soon as the dial moves. Record the reading at it's peak reading. Then continue on until the dial moves again and record. Once you made a complete revolution compare your readings.
If for example you have a reading of +.005 at the 3 o' clock position and then a reading of - .007 at the 9 o'clock position. Your offset is only .002.
I did my measurements 4x's til I was satisfied. So be patient.
[/QUOTE] one small thing.. the instructions that came with my centerforce clutch kit say that the +.005 and -.007 that you mentioned would be .012. the instructions from keisler say same thing.
-.005 and -.007 would be .002, and +.005 and +.007 is .002
Oops, typo... my bad. 
I shouldn't try to type fast late at night
I'll fix it. Sorry 'bout the confusion.
TKO500 5 spd.
Borgeson Steering Box
Born 8/1981
Sequence #3975
Click here to see more pics of my Vette on CarDomain.
Lifetime Member #26
in Forum: C3 Driveline Components
SPONSOR AD: (Our Sponsors help support C3VR)