Topic: P/S Pump & Pulley Fit

[tgilliam]

Looking for information on the "fit" between the P/S Pump shaft and pulley inside diameter. This is for the stock P/S pump and pulley for a 67 Mustang big block. Since there is no key used I am thinking this is an interference fit - possibly "line to line" or -0.001" press fit. Does anyone have the Ford guidelines or recommended proper sizing?
Thanks for your help.

Tom Gilliam
(270) 755 - 6417

[Bob Gaines]

Looking for information on the "fit" between the P/S Pump shaft and pulley inside diameter. This is for the stock P/S pump and pulley for a 67 Mustang big block. Since there is no key used I am thinking this is an interference fit - possibly "line to line" or -0.001" press fit. Does anyone have the Ford guidelines or recommended proper sizing?
Thanks for your help.

Tom Gilliam
(270) 755 - 6417

Yes it is a interference fit. It is pressed on and pulled off . There are specific tools for that job. The alignment is done by pressing on flush with the end of the shaft (at least if you have the proper pulley for the application). 

[67gtasanjose]

Yes it is a interference fit. It is pressed on and pulled off . There are specific tools for that job. The alignment is done by pressing on flush with the end of the shaft (at least if you have the proper pulley for the application).

+1

[tgilliam]

I have the proper tools to remove and install the pulley. I have what I believe to be the original correct P/S pump for my car. It did not have the correct pulley when I got the car so I found one from a vendor. When I tried to install it there was "a lot" more resistance than I expected so I am trying to determine some measurements before ruining either the pump or the pulley in the process.
I have precisely measured the pump shaft outside diameter and found it t be 0.6875" (11/16). From a couple of different sources that looks correct for the pump shaft. I have not found a good reference for the correct pulley inside diameter. Any help on the correct size would be appreciated.
Thanks

Tom Gilliam
(270) 755 - 6417

[RoyceP]

It should be a very tight interference fit. I put grease inside the pulley and on the shaft before using the installation tool with an air impact wrench. Without grease it would likely break something.

[Bob Gaines]

It should be a very tight interference fit. I put grease inside the pulley and on the shaft before using the installation tool with an air impact wrench. Without grease it would likely break something.

+1 . Also be sure no paint is inside of the pulley shaft hole. This typically can happen when the pulley is painted .That paint can cause interference problems. Some pulleys have enough clearance where you can install easy with hand tools others not so much . I always use a impact .I suspect Tom has not done enough installs to be comfortable with the range of possible resistance that can be encountered . Of course if after precautionary measures as mentioned are taken you still find extreme resistance you can hone the hole for more clearance but I have never had to do that.

[Bossbill]

Check the engineering standards.
0.001 to 0.0015  seems to be suggested.
It's tough to measure the pulley's interior bore.

[RoyceP]

Indeed - it's easy to use a caliper or micrometer to measure the shaft OD. It's far more difficult to measure the pulley inside diameter accurately enough to give a dimension for interference fit. You would need a set of calibrated go / no go gages to do it effectively - not something I have laying around.


I suppose I could adjust an adjustable reamer to fit perfectly and then measure the reamer. I have lots of pulleys and Ford or Thompson PS pumps here.

Check the engineering standards.
0.001 to 0.0015  seems to be suggested.
It's tough to measure the pulley's interior bore.

[RoyceP]

Well this afternoon I went through all my reamers and found I do not have one of the appropriate size to work for this. I tried a set of LufKin snap gages to get an accurate inside diameter for the pulley but that was unsuccessful, the number was smaller than the shaft by an amount that was inconceivable (think .005").


With my Brown and Sharpe 579-1 dial caliper the ID measuring side has knife edges so that is probably more accurate, but not accurate enough to make one. It measured the PS pulley ID at .685" - this is an original 6AA pulley in very nice condition.


The shaft OD measures .686" with the same tool. My guess is that the actual fit is more like a difference of .0008" +/- .0001" but I do not have the means to measure to four decimal places.

[jwc66k]

Heat the pulley to 200-225F in your oven (explain the seriousness of this to any and all complainers) for 20 minutes. Using hot pad gloves, install. Have a hammer and block of wood available. Consider putting the pump in the freezer as well (see above).
Jim