Need an engineering mindset…951 crank pulleys

[Drscottsmith]

Ok - I have figured mount my issue with no oil pressure after rebuild. Remember I am also converting over to MS and that is where this problem arises.

So I had everything back together but get 0 oil pressure on mechanical gauge (not to mention dash).

Decided to pull oprv (1986 three-piece) - slides in and out just fine.

So now to front of motor - figured I had done something backwards. Pulled all gears off (again) and nothing looks out of order…did notice however that the new green o-ring between the washer and oil pump drive gear was not really compressed at all by the washer as it should when the crank bolt is tightened (it was spot on 155ft/lbs, btw).

Then it hit me. The pressure to clamp that washer down comes from the crank bolt through the tapered washer, through the bottom of the power steering pulley, to the balance shaft pulley, against the timing belt pulley, then finally against the washer and o-ring.

Well I have added ~7mm of depth between the ps pulley front and the washer, in terms of the crank gear and the 4 bolts attaching it to the balance shaft pulley through spacers.

When I tighten the crank bolt, it is now tightening against the top of the bolt heads that sit proud of the crank gear but not behind the rear lip of the ps pulley, and reaching 155ft/lbs before it reaches the bottom of the ps pulley, and it never compresses the washer and o-ring against the oil pump drive.

So - I think I need to add abt 7mm somewhere to compensate, but I can’t figure out where.

Thoughts? Here is a rough sketch -

Thanks!

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[four0four]

To naively answer: Behind the PS pulley, I think. Simple part, spaces out the problem, doesn't result in a buncha stuff being extended.

A question though - Is 7mm the amount those heads impinge on the pulley, or just the amount it's spaced fwd? If the latter, how much actual clearance is required? And could a low profile bolt help achieve that? Thinking something a la the 951 water neck bolts (Belmetric carries 'em).

Good find

[Drscottsmith]

The bolt heads are 5mm thick, and the trigger wheel is 5mm. About 3mm of the bolt heads underneath the rear lip of the power steering pulley, so that is where I am thinking 7mm total to add so that the ps pulley presses down as it is supposed to against the other pulleys and ultimately the oil pump drive.

I believe a low profile bolt would work - also thought about grinding the bolt heads down by 3 mm.

Another option would be drilling holes through the ps pulley in the 4 spots where the bolt heads would be to allow them to recess, but that is right in line with the long taper and would be rather tough to drill methinks.

[chris white]

I have some laser cut spacer washers for that exact spot! I use them because the my trigger gears mount in-between the ac/alt pulley and the balance shaft gear and that pushes the outer edge of the ac/alt pulley out enough to interfere with the PS belt. My solution was to shim the PS pulley out. This may help you out with your issue.

[Drscottsmith]

Thanks all for the replies. So it sounds like the consensus is a 7mm spacer/washer/stack of washers on the bottom of the Power steering pulley up against the balance shaft pulley. That will allow the power steering pulley to tighten down to 155 ft/lbs against the balance shaft and timing pulleys before it bottoms out against the trigger wheel and alternator pulley.

I don't see anything online that fits the bill (McMaster, etc.) - I may get 3-4 of the washers that go up against the o-ring behind the timing pulley and stack them since the ID and OD will be correct. Also considered a second tapered washer behind the PS pulley (same as in front) but the taper worries me a bit - would like to have as much surface as possible - especially since the PS pulley will not be sandwiched between two spacers.

[chris white]

So, not interested in one of these? 3.175mm thick and laser cut to precisely fit on this location.
Btw- if you add washers to the back of the ps pulley it will no longer be centered on the crank, it only engages the last three mm. Unless you weld the spacers to the pulley the chances of gettting it centered are pretty random.
If you add 7mm of washers the power steering belt will not be in alignment, there is a little fire/aft adjustment on the ps pump, I can fix for 3mm but 7mm might be a stretch.
I’m cheaper than McMaster….I only charge one beer unit if you ever meet me!
Btw - my solution to the same trigger wheel mounting issue was to sandwich the wheel between the balance shaft gear and the ac/alt pulley. This does not change the stack height and no extra bolts needed

[Drscottsmith]

Yep Chris that is a perfect solution. I'll take 3. (That way I will have an extra when I screw one up).

I did consider welding to the back of the p/s pulley. I am still trying to wrap my head around how you placed your trigger wheel, spacers, etc - the whole process. Do you have a pic?

My trigger wheel is cut already to fit the P/S pulley inside it. Would have to fab up a new bracket for the sensor as that would change if I moved the trigger wheel. I built adjustment into it for height and angle but not for fore/aft shifts. Problem I have is that moving where I think yours is will require cutting the rear belt cover. Open to ideas. Here are a few pics:

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Let me know how to proceed (PayPal, Venmo, etc.)

-Scott

[chris white]

my trigger wheel is set up to mount between the ac/alt pulley and the balance gear. Laser cut to math the OD of the lip on the ac/alt pulley so it centers automatically. trigger wheels don't like run out! The OD of the trigger wheel (60-2 tooth) is designed to fit inside the belt covers. all that is needed is a small hole for the sensor at the bottom of the belt cover. as a hold over from the electromotive days the mounting position is set so that the sensor is pointing at the 11 tooth after the missing teeth. not critical anymore but is still handy to know the trigger timing.

[Drscottsmith]

Chris - looked at everything when I got home and looks like your spacers are the way to go.

I think welding them to the back of the ps pulley is best bet, but I did wonder that as the crank bolt is tightened, that would pull the edge of the pulley back over the crankshaft enough to center it?

Still - welding will get it right the first time. In my setup I would have to cut up the front and rear timing covers to put my trigger like you did between the larger pulleys.

PM me or let me know what to do next

[chris white]

Chris - looked at everything when I got home and looks like your spacers are the way to go.

I think welding them to the back of the ps pulley is best bet, but I did wonder that as the crank bolt is tightened, that would pull the edge of the pulley back over the crankshaft enough to center it?

Still - welding will get it right the first time. In my setup I would have to cut up the front and rear timing covers to put my trigger like you did between the larger pulleys.

PM me or let me know what to do next

there is only a very small over lap of the PS pulley and the crank snout - about 3mm. even with the 3.125 mm spacer I use the PS pulley never makes it to the crank snout - thats why you have to center the spacer and weld it.
Let me know your shipping address and i'll send you a couple.