Dialing in a repower bellhousing

[Daxman]

Hi Guys,

I'm after some advice,

I have just tried to dial in my bell housing, left to right is bang on but top to bottom is way out (0.054") which is alot.

Can i just confirm that i'm doing right, i set up my DTI at the 12 o'clock position an set the DTI to zero, then turn the engine to the 9 o'clock position and take reading (-0.73mm or -0.028") then turn to the 6 o'clock position take reading (-1.38mm or -0.054"). Turn to the 3 o'clock take reading (-0.70mm or -0.027") then back to 12 o'clock take reading (back to zero) See attachment.

so as you can see left to right is within tolerance (0.005" difference) but the bell housing needs to be raised by approx 0.027".

But by raising the bell housing that much i doubt i will be able to get any of the bolts in.

Is there a fix for this? i have heard of offset dowels but can you get them with that amount of offset.

Thanks in Advance,

Russ

[grahamf]

Russ
Denis (ooglyoodoo) and I dialed in his bellhousing in the following manner;

The bellhousing was bolted on to the block with straight pins,
The dti was set to zero at a point,
We rotated the crank in steps, about 10degrees or so, not measured, and recorded the dti position and reading with black marker on the bellhousing face.
This showed much more detail than the NSEW system you are using.
We did this twice more to check,
We then worked out the difference between opposite measurements, found the greatest difference and the angle at which it occurred.
Halve that difference then thats the offset you will need.
You could always PM Denis as he took pics of the readings to make it clearer.

It sounds more complicated than it really is, its just time consuming really, but much nicer in a carpeted garage!!!!

HTH

Graham

[Toddy]

Russ, are the readings repeatable ?
are you sure the DTI didnt hit anything ?
Not trying to tell you how to suck eggs
Bolts should fit Ok if you offset it its only 1/2mm

[FatBoy]

54 thou sounds a lot, but remember you only need to move it by half that amount i.e. 27 thou to centralise it. An alternative to offset pins are the weld in bushes.
Here is a detailed explanation on how to dial in a bellhousing, albeit on a Kirkham.
Kirkham Motorsports Assembly Manual - Page 4 - Club Cobra
It starts from post #51 about half way down the page.

Paul

[Daxman]

Yes checked it several times, all with very close readings. I'm going to get the spare DTI from work tomorrow and try it again.

I see real steel do 0.014" offset dowels, however from my calcs i need 0.027" offset dowels, does anyone know if it is possible to get these.

The other option is to drill through the bellhousing and block and put my own dowels in. is this O.K

Russ

[Clarkson]

Russ, make sure there is no paint or crap on the face of the block were you bolt the bellhousing too. That makes a massive difference.

[Daxman]

Originally Posted by FatBoy

54 thou sounds a lot, but remember you only need to move it by half that amount i.e. 27 thou to centralise it. An alternative to offset pins are the weld in bushes.
Here is a detailed explanation on how to dial in a bellhousing, albeit on a Kirkham.
Kirkham Motorsports Assembly Manual - Page 4 - Club Cobra
It starts from post #51 about half way down the page.

Paul

Thanks for that Paul, a very interesting post. I'm going to have another go tomorrow, and see what happens.

Russ

[TINKA]

Originally Posted by Daxman

Thanks for that Paul, a very interesting post. I'm going to have another go tomorrow, and see what happens.

Russ

Hi Russ, Paul has done it the best way as far as I am concerned. Just one question exactly how are you mounting the dial gauge? The method stated in most text books is to use a magnetic base on the fly wheel, but having done this once in the past, but twice recently I have tried it slightly differently. I bought a clutch aligning tool and cut the end off and also cut a slit in it so I could bolt the dial gauge directly to the end of it and it would be in exactly the correct position to run around the lip on the gear box. Then I fitted the complete clutch assembly and put a couple of small wedges between the fingers of the pressure plate and the clutch tool so it could not move at all, then did exactly as Paul says with the straight pins first to ascertain which direction it needed to be moved in. This is the easiest way I have found to do it and seams more accurate as the gauge is held so much more rigidly. One thing you might want to check is that the dial gauge is being held rigidly enough as the first couple of times I did this a couple of years ago I never noticed a slight movement of the dial gauge as it went around due to gravity. Worth checking. HTH

[dave]

I think there has been a vital measurement missed out.

Before you dial in the hole in the bell housing you really should dial in the rear face of the bell housing to make sure that the box mounting face is perfectly parallel with the flywheel, otherwise no ammount of adjusting the centre hole will guarantee proper alignment.

Hope that makes sense.

[FatBoy]

It does make sense, but how on earth do you adjust that, or do you simply send it back for a replacement if it isn't right?
I understand the logic, but I've never heard of it being done before. I had assumed that it was taken for granted that the gearbox face was parallel to the engine face.

Paul