Cam Sensor gear / Cam gear wear

[10SV6]

I pulled the cam sensor out of my on center motor last night. The cam gear and the cam sensor gear are both worn to pretty close to knife edges. I've heard about this type of wear before. The motor has a production front cover with the balancer shimmed out to line up the pulleys.

I know the proper fix is to machine the front cover. When the front cover is machined does it completely take off the top dowel alignment tab ? Has anybody thought about shimming the cam gear out. It's going to put the gear over the end of the cam snout is the only problem there.

The motor has a Precision 236/236 solid roller cam.

Any ideas ?

Thanks
Paul Thompson

 

[Ron Tarabori]

Gear wear

The easy way is to make a washer to fit against the timing gear that will shim everything else out. Usually about .060 to .100 will correct it. Look back through the posts. This was covered in some detail a while back. Ron

 

[9SECVSIX]

Cam gear ware.

10SV6. Search the word "Torrington" and you will see a lot of posts about the roller cam nose problems. I couldn't find anything about the torringon cam bearings( what I was looking for) but I thought i saw stuff earlier in the winter.

9secvsix

 

[10SV6]

Dumb azz me should have looked closer. Doh.

www.turbobuick.com/forums/showthread.php?s=&threadid=27229&highlight=cam+gear

Should the centerline of the cam sensor gear be at the center line of the cam gear ? The reason I ask is that alignment, centerline perpendicular to centerline, looks to be father out than .120". I'm guessing that the cam has Precision's thrust control stuff on it.

Paul

 

[Mac in SD]

I've been wrestling with this, too... I had already gotten a front cover machined .120 (like the Good Buick Book says), when the topic of a .120 spacer behind the balancer was suggested, instead. Meanwhile, good ol' Neal loans me a stock front cover so's I can just use the crank balancer spacer method. So I look at the alignment of the cam gear to the distributor/cam sensor bore on both the .120 shortened cover and the untouched cover, and I gotta tell ya'....the .120 machined cover lines up dead center. The stocker puts the distibutor/cam sensor gear wayyy out there on the front edge of the cam gear, according to my eyeball.

I just have a feeling that when all the Buick Motorsports and Ruggles books tell you that the cover must be shortened .120, it's not just for water pump and accessory pulley alignment. Again, just MHO.

 

[Alky V6]

I understand that the gear wear will happen even when alignment is right on. You should run a bronze driven gear if it's available. That way the bronze gear will wear the most and hopefully save the drive gear on the cam. You'll just need to inspect the driven gear at regular intervals and replace it when it gets too bad. Hopefully you won't have to tear the front cover off and do the drive gear also. I noticed this wear on my old motor and with high oil pressures I don't see anyway around it. The next motor will be dry sump so I won't have to deal with that problem again. Maybe someone else can tell you if a bronze gear is available for the sensors.

 

[9SECVSIX]

My oil pump shaft is on center with the cam gear but with the big gear oil pump i still has noticable gear ware after ever race season, I usually put a new gear on the cam ever over haul, the bronze gear would be a excellent idea if they are available, I asked around a few years back and couldn't find a supplier.

 

[Mac in SD]

Why is this happening? Why would it happen with an odd-fire timing gear setup, but not with a stock even-fire setup? I could understand it if we were getting wear on the odd-fire cam gear (maybe different metallurgy from the integral gear on the stock-type cam), but why on the cam sensor gear? Or is this simply due to everybody running larger oil pump gears?

 

[Alky V6]

I think KenneBell has the bronze gear for the distributor setup. Not sure if it would fit the sensor. If the shaft bore in the bronze gear is smaller, just machine the hole bigger. There may be a difference between the two cam gears like you said. One thing I know that would aggrevate the wear is high idle oil pressures along with the high max pressures that most of us would run (80 psi). Typically, the face clearance of the pump gears is on the high side, which helps to give you the low idle pressures in the stock motor. Most engine builders will tighten up the face clearance to make the pump more efficient, along with higher volume pump gears and the idle pressures come up. At idle maybe there isn't a lot of oil getting to that gearset to help with the added load it's seeing at idle. Just my theory. At any rate, the load we're putting on the gear set is greater than the design is meant to handle.

 

[10SV6]

Ok, I took the front cover off tonight. The cam gear is a few thousandths short of the cam snout, with a pocket machined in the gear for the retaining washer.

The block is a 153 casting, on center with cross bolted front and rear caps.

I spoke with Dave Weber - he makes cam retaining hardware, yesterday. I also spoke with Dan from Precision. Both mentioned that on offcenter blocks that the cam snout is machined .150" to make room for the roller bearing bolt. The only problem is that I need the extra .150" to move the cam gear into alignment with the cam sensor gear.

Looks like time for another cam.

Anybody looking for a Precision 236/236 solid for a offcenter block ? Less than 50 passes, no street miles.

Paul Thompson

 

[The Radius Kid]

That bronze gear *may* be available for GM HEI distributors.You'll need the shaft size and length,etc.If so,set your end clearance and go.Maybe a good time for a roller thrust setup on the cam sensor?

 

[GARY HARVEY]

wear?

I've noticed that this thread has not mentioned any reference to the alternate metal treatments that are available. Has anyone looked into cryogenic or the coatings industy for help? Check out 300below.com or plug into cryogenic treatment via google for the info. Dave Emanuel has several
writeups concerning these processes that make for good reading.

I seen throw away razors that stay sharp for an amazing amount of time through cryogenic treatment and coatings on top of that improve things even futher. Secrets like this are a common thing in the engine depts. of many of the better engine shops, but very few people want to mention their findings.

 

[10SV6]

After getting a new cam and shimming the cam gear out to the proper distance, I haven't had any more wear problems.