Camshaft removal

billd · 09-18-2006, 06:52 AM

I'm disassembling a Carerra 3.0 motor and its not clear to me how to remove the cam. It doesn't have a large nut on the cam, and flats on the end of the cam (for the cam socket) like the other 911 engines I've rebuilt, but rather has a bolt in the end of the cam. How am I supposed to hold the cam from rotating while I remove this bolt?

I should add that the cam towers have an odd part number, 901.105.111.1R. That doesn't match the 930.105.021 number I would have expected for a four-bearing cam tower. Does anyone know what this is off of?

billd · 09-18-2006, 06:53 AM

Picture

john walker's workshop · 07:18 AM

you're screwed in this instance, because someone used the wavy washer from the early cam under the bolt and washer from the late cam. you will need to use a socket and breaker bar, gently as possible to remove the bolt. it stresses the chain and intermediate shaft gear to do it that way, but you have no choice. can't say i've seen that trick before. normally the holes in the sprocket are visible so the proper cam holding tool can be inserted into them. makes you wonder how they got it tight.

billd · 09-18-2006, 07:35 AM

Is there any easy way (tool) to hold the timing gear by its teeth?

Henry Schmidt · Henry Schmidt's Garage

I would just hit the bolt with a 1/2 inch impact. The impact action will put less strain on all parts do to the short blasts rather than long sustained torque.

It is not a great situation to be in but that is what I would do.

As for the cam tower, there were 4 journal cam housings made in late 76 early 77 that had this casting number.
The new casting was used in 2.7 three journal applications as a transitional part and later machined to fit four journal cams.

billd · 09-18-2006, 09:09 AM

The impact wrench sounds like the best bet. Would you recommend that I remove the chain tensioner first - so that the impacts will just spin the camshaft - rather than load the chain and intermediate shaft? Or do you think that the inertia of the camshaft won't be enough to loosen the bolt?

I'm also considering trying to make a tool from a piece of old timing chain and a breaker bar - to loop around the gear and hold it in place, but I don't know if it will fit - even with the tensioner out - there is not much clearance between the gear and the chain.

Henry Schmidt · Henry Schmidt's Garage

Leave everything assembled and just spin the bolt.
No harm will come to any ancillary parts.

If you spin the cam with heads installed you could have valve to piston contact resulting in bent valves and/or piston damage.

billd · 09-18-2006, 09:49 AM

OK, I'll try it all assembled and hope I don't break anything. I was going to remove the rockers first to avoid valve problems.

billd · 09-18-2006, 07:09 PM

Another question - having never rebuilt an engine with one of these bolt-snout cams before: is there supposed to be a small spring washer under the thick washer? Or does the thick washer go directly on top of the timing gear? If the former - what's the PN? Thanks.

Henry Schmidt · Henry Schmidt's Garage

Bolt and thick conical washer only.

billd · 09-21-2006, 09:29 PM

Thanks much Henry and John. I applied an impact wrench with a 19mm socket to the bolt and it came right off. I don't think it was that tight. Nothing seems damaged.