Broken camshaft

79sharkguy · 79sharkguy's Garage

Anyone have a spare 78-79 right side camshaft you're wanting to sell? Out of nowhere the end snapped off while driving...

Mrmerlin · 07-15-2011, 09:05 PM

Ahh sorry but is this the driver side or the passenger side cam??
Reason being the one that snaps is the driver side cam.
What was the tension of the timing belt?
Did you use a Kempf tool ?
if so then it should be adjusted to the low side of the window,
the later 32V cars get adjusted to the high side

79sharkguy · 79sharkguy's Garage

Passenger side (US). used the kempf tool adjusted to the lower portion of the window. It was running GREAT! I was almost thinking too little tension may have been at fault...

Mrmerlin · 07-16-2011, 05:13 AM

thats strange for the pass side to break, usually the bolt that holds the cam on may have been overtightened

DPW928 · DPW928's Garage

The early 928's used halfmoon shaped woodruf keys to align the cam gear. This created a weak point where there is about 1/16" of metal between the key cutout and the bolt hole. This wasn't a problem until the oil industry came out with low zinc oils which increased the resistance at the cam lobes. Since the drivers side cam gets the initial torque on start up, they normally crack first (like mine). You may want to pull the gear on your drivers side and check it for cracking. Also make sure you are using high zinc oils.

79sharkguy · 79sharkguy's Garage

I'll definitely check the other side. TB did seem to be tracking a little more to the front. I'll upload a pic later of the damage; definitely looks like a break near the woodruff key slot. I've got some checking to do to see if I can figure out the forward tracking issue but first I need a new cam. 928intl has one for 250. Can anyone beat that?

DPW928 · DPW928's Garage

The forward tracking could put more pressure on the cam. $250 is a good price and their warranty is hard to beat.

harborman · harborman's Garage

Quote:

Originally Posted by Mrmerlin

Ahh sorry but is this the driver side or the passenger side cam??
Reason being the one that snaps is the driver side cam.
What was the tension of the timing belt?
Did you use a Kempf tool ?
if so then it should be adjusted to the low side of the window,
the later 32V cars get adjusted to the high side

Mrmerlin,

You are the Ace in the hole on this site! Thanks for all your good advise over the past year and a half and along with others!

sonett3 · 07-17-2011, 05:44 AM

I have a set of 1984 cams if you are interested?

79sharkguy · 79sharkguy's Garage

I might be interested in 84 cams if they're euro :-) Otherwise I think it would be best to stick with the 78-79 cams.

Brings up an interesting question: would I see a decrease in low end power with euro s2 cams?

79sharkguy · 79sharkguy's Garage

Here's a couple pics of the damage. You can see where it snapped near the woodruff key slot. I installed offset keys to advance the valve timing aprx 4 degrees...

sonett3 · 07-17-2011, 03:57 PM

No They are US 84 Cams. You can get them reground but I don,t know the cost to do that.

DPW928 · DPW928's Garage

The offset keys shouldn't have caused a break in the cam. BTW the CIS cams have a higher lift and longer duration than most of the later US spec 928.

Danglerb · 07-18-2011, 02:07 PM

Quote:

Originally Posted by 79sharkguy

I might be interested in 84 cams if they're euro :-) Otherwise I think it would be best to stick with the 78-79 cams.

Brings up an interesting question: would I see a decrease in low end power with euro s2 cams?

What low end power?

None of the factory cams are aggressive enough to make much of a difference below 3000 rpm, but above about 3500 rpm you will feel the Euro S pulling harder. Euro S cams are not cheap, but a little less than a reweld and grind which is around $1k or so plus a core (I used an 80 for a core as I recall). I wouldn't spend the money without the heads and intake to take advantage of the hotter cam.

BTW I pretty sure I have a cam, but I want to put my hand on it and check the grind before I say for sure.

79sharkguy · 79sharkguy's Garage

Yeah totally agree; car's got nothing down low. Even after a P&P, emissions and a/c delete, e-fan installation, and advanced valve timing it still barely chirps the tires off the line.

Definitely need boost and/or a 150 shot of NOS! But I digress... Believe I've sourced a pair of cams so thanks everyone for checking. While I'm in there, anyone have any ideas on the forward tracking issue?