1983 US-spec 308 QV – Cam Shaft Protection from a Seized Air Pump

On a 1983 US-Spec 308 QV, how is the cam shaft protected if the air pump seizes?

My air pump is freewheeling because somehow the dowel pin securing the pulley on the cam shaft had fallen out. It is item 66 on the below diagram. I purchased an official size and weight Ferrari part number 100279 replacement dowel pin and after a short while it fell out too.

... It seems like installing a pin is pretty foolproof, but I may be underestimating my incompetence.

One friend machined his own pin out of brass and installed that. Another friend just pushed in a hardened steel spring pin saying there was elsewhere (Item 77?) that is designed to break if the smog pump seizes. How is the cam shaft protected from a seized air pump?

I am looking for input on what to replace item 66.

Given that a friction fit of the dowel pin doesn’t seem to stay, I am wondering about alternatives ranging from a short piece of soft copper wire to a plain bolt and nut.

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71 protects the timing belt if the pump seizes. 66 is a roll pin and should be a tight fit so it does not fly out when spinning. If it is coming out it is not the correct part and too loose a fit. 65, the drive flange comes off easily. Take it off and take it with you shopping for a roll pin.

 

wow... I'm extremely glad I have a 85 car... no smog pump! Sorry Brian A

 

On my 83 the smog pump was removed

 

I tried replacing that pin with a brass rod that was (mostly) a press fit. It was a bad idea and my poor execution couldn't over come that. Use a real steel roll pin.

 

I've searched a bit and have found plenty of reports of the roll pin being too loose. People are using Loctite to keep it in; an idea I don't like.

Given that item 71 provides the shear protection (Photo of broken part 119215), is there anything wrong with simply using a 4mm bolt with a Nyloc nut? (or a cotter pin for that matter.)

My $12 (!) 4mm dia factory roll pin (part 100279) fell out and I am not hopeful finding a different roll pin that is just a minuscule bit tighter.

 

On 308 from the 70s with two pumps, the belt just melts...ask me how I know...

 

Not sure what the source was ultimately for the "factory" roll pin but it sounds like it came from a bin box at the hardware store. Every factory roll pin I installed made me think I was going to break something pounding it in. My experience with using a screw ti attach a pair of spinning parts in that way has never been satisfactory. It is a cheap solution if it works.

 

Like I said Brian, I got my roll pin at Ace Hardware. I just got a couple of sizes and used the one that fit. Maybe you're over-thinking this a tad? The pulley pin is not the fail-safe point, it's the coupler with the narrow neck section. I know because mine was broken and I bought a new one. (item 71 in the diagram)

 

It can't harm the cam shaft if it's sitting in a box. Just sayin'.

 

mines on the shelf also

 

Not one of the choices in the San Francisco Bay Area.