Re-installing distributor 1970 350?

[Mike F.]

Trying to re-install my distributor. The distributor installs, but doesn't sit flush with the intake manifold. It sits up about .010-.020. Just enough where I can grab it and wiggle it around.

The oil pump is a high volume one, where the shaft is attached with a steel collar. I've tried to remove the shaft with a magnet, it will not come out, so the steel collar is still in place. When I turn the pump with a screwdriver, I can feel resistance, so the pump is working.

It seems like I've had it in and out about 200 times, adjusting the oil pump shaft 1/64 turn at a time. It appears that the distributor shaft is going into the oil pump shaft, I can see that the oil pump shaft has rotated/moved once the distributor is installed and them removed.
When the oil pump shaft is completely mis-aligned, the distributor sits up about 1/4" or so as expected.

What is keeping the distributor from dropping down that last .010-.020 and sitting flush?

Thanks,
Mike

[Duke W.]

Re: Re-installing distributor 1970 350?

It sounds like the pin on the dist. is bottoming out on the oil pump shaft slot. This could be caused by excess machining of the block, such as decking and removing material from the front and rear block bulkheads to align the ports or removing material from the inlet manifold distributor pad. Or it could be too long a shaft out of the pump or a too long intermediate shaft.

If the above is true I would suggest fabricating a .030" spacer and using a gasket above and below it to ensure that the pin doesn't bottom out in the slot when the dist. is snugged down.

Also make sure the dist. gear isn't on upside down. I've heard that it can actually be installed that way.

Duke

[Joe L.]

Re: Re-installing distributor 1970 350?

It sounds like the pin on the dist. is bottoming out on the oil pump shaft slot. This could be caused by excess machining of the block, such as decking and removing material from the front and rear block bulkheads to align the ports

Duke

....or excess machining of the cylinder heads or intake manifold. These things also beget other problems.

[Mike F.]

Re: Re-installing distributor 1970 350?

This seems to be a new problem. I've had the distributor out in the past and never noticed this wiggle before.

While it is normal for the oil pump shaft to have some up & down play, is there any possible way that the oil pump shaft isn't moving as far down as it could?

[Duke W.]

Re: Re-installing distributor 1970 350?

The pump shaft end play should be no more than a few thou. Why did you remove the dist. and what did you do with it?

If it was properly seated when you removed it then you must have done something wrong along the way.

It's also possible that you haven't successfully lined up the pin with the pump intermediate shaft slot, but that will usually stall the installation at about a quarter inch above seated.

Duke

[Mark E.]

Re: Re-installing distributor 1970 350?

Duke,

Would you say more about "It sounds like the pin on the dist. is bottoming out on the oil pump shaft slot."? Can the distributor gear roll pin somehow contact the pump shaft?

Also, would adding a shim between the manifold and distributor housing affect cam-distributor phasing?

Mike,

If everything was ok before the distributor was removed and nothing else was changed, what comes to mind:

- Are you using a distributor seal? I don't know the amount of axial clearance there should be between the dist. and oil pump shaft (maybe Duke or Joe know) but maybe the lack of a seal can cause interference? (But it seems like there should be more axial clearance than the width of the seal. Plus, I've installed distributors without a seal with no interference problems.)

- Did you add shims to the distributor shaft? Or change the distributor shaft with one that's slightly longer?

- Make sure the dist. gear roll pin ends do not protrude past the gear housing.

- Burrs or imperfections in the dist. gear or dist. housing? For grins, trial fit another distributor and see what happens.

- Dirt/debris in the oil pump shaft slot? Or in the bottom of the dist. gear?

- Try reorienting the oil pump shaft 180 deg. Who knows, maybe that will help the dist. gear to seat better.

- Is the dist. gear dot lined up with the rotor tip? Again, who knows, maybe that will help.

- You mentioned you're using a high volume pump with a metal collar. Does this set up have a longer shaft length than stock? This didn't change since the distributor was removed but maybe you just didn't notice the lack of clearance before. Or maybe the longer shaft length combined with any of the above changes is now making the lack of clearance noticeable.

[Duke W.]

Re: Re-installing distributor 1970 350?

Duke,

Would you say more about "It sounds like the pin on the dist. is bottoming out on the oil pump shaft slot."? Can the distributor gear roll pin somehow contact the pump shaft?

Also, would adding a shim between the manifold and distributor housing affect cam-distributor phasing?

The roll pin that secures the gear fits into the slot in the intermediate oil pump shaft, and that's was drives the oil pump. The slot is about a quarter inch wide and about 3/8" deep, so there's plenty of vertical tolerance, but if the intermediate shaft is not fully seated on the oil pump output shaft it could be too high. Adding shims or extra gaskets won't affect distributor phasing other than maybe requiring a slightly different position of the housing to achieve the proper initial timing.

The OP seems to have gone AWOL.

Duke

[Mark E.]

Re: Re-installing distributor 1970 350?

The roll pin that secures the gear fits into the slot in the intermediate oil pump shaft, and that's was drives the oil pump.

Thanks. It's been awhile since I took one of these apart. I didn't realize that the roll pin is the part that engages the slot in the oil pump shaft.

[Ken A.]

Re: Re-installing distributor 1970 350?

This is incorrect. The distributor shaft drives the oil pump

[Duke W.]

Re: Re-installing distributor 1970 350?

I stand corrected. It's the flat machined at the end of the dist. shaft that engages the slot in the intermediate oil pump drive shaft... had a case of brain fade. It's been about three years since I took one apart.

Duke

[Mike F.]

Re: Re-installing distributor 1970 350?

I'm still here. I just haven't accomplished much on the car. I removed the distributor to just reclock it, due to a slipped harmonic balancer. (Long story in another thread). I'm just trying to get the car running. Burned up the Restoration Battery with all of the cranking. So now I'm dealing with the battery issue.
I have 20 days until the Texas Regional (which doesn't look good) and we're moving from our temporary apartment to our new house on Nov. 20th. Running out of time and options. Other than that, I still have my looks.