Cam gear locating pin broke

Alright maybe it isn't called the cam gear locating pin. Is it a dowel pin? Anyway, I was putting the new springs on the heads in the car (installing a roller cam project) and I had one side done, the rockers were all on, but loose as I had not set the lash yet. For whatever reason I wanted to rotate the engine, so I did and thats when the cam pin sheared off. Let me explain, there was NO bolt in the cam, and it was likely not all the way back.



So I cussed a bit and then finished out the spring swap on the other side and then decide to drill out the pin. Thats when it got worse. I drilled it out and tapped it and then used a slide hammer to remove the pin, except the pin did not come out. It pulled the threads off of the tiny cheapo bolt. So I drilled a bigger hole and used a bigger tap and then made the best (&*^% of the night when I broke the tap off. Game over, time for bed.



Now for the questions! Does the cam bolt do most of the work holding the gear on? At what spring pressure, RPM, lift or whatever variable should one double pin a cam? AND here is one that puzzeled me, the cam has two pin holes (the gear only has one like all of them I have seen) if there was no pin in the cam how would one know where it wold go??

The pin is really just a locator, the press fit of the gear to the cam is what keeps it from spinning. This is why the bolt and washer are real important. The pin does offer some holding power, but with no bolt pressure like that its doomed.

i myself have never had one break
but i have seen it happen to other's
now for every build i use 2 pin's
no matter if it is a mild street stomped or a all out race motor
it is a pice of mind if anything
and it isnt very costly to do
i think my comp cam was like 30.00 extra to have the 2nd pin
and i just drilling out the gear

Thanks guys.

The Bolt and washer does most of the work. MAKE SURE TO USE A VERY THICK/HEAVY WASHER and torque down good. I use a washer from sbc harmonic balancer.

The pin is very important, you need to have one or two prefered. The bolt and washer only holds the gear inplace, the pin / pins allow it the gear to turn the camshaft.

So... Both the pin(s) and the bolt are important. I'm leaning towards double pinning the gear since the cam already has two holes, well one hole and one full of broken tap
I have yet to do anything about that, I have a machinist friend that may be able to fix it on the cheap whom I will see tonight.

One question remains, about the pre-drilled pins in the cam, how does one know which is the 'primary' one? It does not appear to be marked on the cam.

2 pins are ok, but another good way which is really good is to add a woodruff key 180* from the pin and have the keyway broached in the gear. You will never have to worry about a broken pin again. Just my $.002

I had this happen as well, unfortuneatly it was at about 6000 rpm and 1000', banged some valves, was looking into doing the double pin thing, I am taking it that it something I should get a machine shop to do

Morris

the pin does little work, two pins and leave the bolt loose-- 2 broken pins. Now to fix your cam, turn (gear on cam) 180 degrees bolt in down-drill new dowel hole--fixed. cam gear- mark new dot 180* from original , just to make it easy for line up. degree in the cam will be a must.

What is the torq spec on the cam bolt?

I use 45# w/loctite on the 3/8" bolts and 65# w/loctite on the 7/16".

I have never found the torq spec on the two little bolts that hold cam plate on. Can someone give me that also.

i did the woodruff key thing and a pin in my set, solid roller cam, then used the SBC harmonic balancer washer as stated above and checked end play, piece of mind i guess

rick

should not of tried turing it over with rockers on,and cam bolt not in,ive seen 3 people do this,brake dowel off