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Discussion Starter #1
On the dyno the other day I noticed valve cover bolts were backing out. (No biggie) Started looking around real good and noticed 2 intake bolts had backed out a little. (Still no huge problem) well went to the track Sunday and was having problems getting it to build boost. Tried 4 times... On the 4th run it didn't want to move so I cruised down the track and at the first return road it died. Started back up and made it almost back tO the trailer. Got it back to the trailer and Checked all the Obvious before cranking it again. Tried to crank and it sounded weird... Oh well I'll load it up and check tomorrow. Today I Pulled the valve covers and plugs. Was expecting to see a rocker stand or something loose from the history of stuff backing out. Nothing out of the ordinary again. Checked the rotor... Loose as fuck! Theirs the problem... Sweet! Wrong. Tried to start nothing. Pulled the cap bumped it.... Rotor didn't move! Well fuck now I'm yanking the front end apart. How often do the pins In the cam and timing gear sheer off? That has to be it... Im pulling it apart tonight. I'm thinking it's time tO switch to a belt drive to minimize harmonics in the valve train.. Any opinions or personal experience would be appreciated. Thanks, Eddie.
 

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I've only seen the cam pin shear once in the 15 years I've been working on the SBF. The fact that it wasn't building boost before makes me wonder if it sheared the distributor cam gear pin. I've also seen that magic trick. If it did shear the cam pin check the valves, chances are they have touched down.
 

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I have seen this happen on a SBF a bunch of times. Drill out the small drive pin that MSD uses and redrill for a larger solid pin.
 

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Since you said the rotor was loose I'm assuming that you could spin it around by hand. If that's the case then you didn't shear the cam pin because youd be spinning the valvetrain and oil pump by turning the rotor in that situation. My money's on the roll pin for the distributor gear or the gear itself.
 

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Discussion Starter #5
It's an external oil pump. It sheared the cam dowel pin. Not the distributor roll pin. Wtf causes this?

 

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Did the cam spin pretty freely in the block with the retainer all bolted up? Just looking at how ate up the inside of the retainer looks. It's hard to see in the pic for sure.
 

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Discussion Starter #8
Spun fine!I want to know why it walked forward... The pin obviously walked forward slowly out of the cam. It ovalized the hole in the timing gear..... that tells me it didn't happen all at once. The groove in the retainer is around .067 deep.
 

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Discussion Starter #9
Nobody has had the cam walk forward? Someone has had to had this kind of problem.
 

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Yeap had this happen to me as well . It killed the motor doing it to . Cam did not walk only broke the pin because of seat preasure on the valve springs is what broke mine .

Double pin the cam into place and get good harden pins to put back in there and youll be fine from there .

Good luck man .
 

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I have never had the pin push itself out. I have seen them break. To many rpms, and valves get out of whack.. Check the pushrods to to make sure they are all straight. I bent all 8 intake pushrods when it did it.
 

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Discussion Starter #12
My push rods are nearly impossibly to bend. 3/8" .145 wall
 
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