Broken Timing Gear Bolt in Cam? Need a new Cam? Recommendations for a lifted DD?

[boy&hisdogs]

Yes, it is a stepped nose, steel core, hydraulic roller camshaft that GM used with un-touched Vortec heads. It bolts in with zero other changes. Intake lift is 0.452 and exhaust is 0.465 making it compatible with stock springs, retainers, seals, etc. You can re-use your lifters provided they are in good condition even.

What about gas? Does it run fine on 87?

I'm new to this stuff, are there any downsides or concerns I'm not seeing?

 

[L31MaxExpress]

These were late 80s and early 90s vans, this company distributed and merchandiser books and magazines. We worked for them from '96 to 2009. Those heavy duty black plastic totes in the bed of Rawhide in his loaded picture, came from a later incarnation of that company. These vans were used for deliveries, and you know how most people drive a truck that isn't theirs....
Once they had Mom and I go to Austin, to swap vans with another supervisor, and the one we got had a rear axle bearing going bad in it. You can probably guess how fun that trip home was...that bearing howling, and the noise getting amplified by the giant speaker box that is an empty cargo van....
Another one was out of inspection, wouldn't pass without several bulbs and a headlight being replaced. And then they didn't want to reimburse me for the parts and inspection fee.
Also since they were unit body, they'd get to where the side doors didn't want to close right, barn doors or slider.
They replaced the Chevy and GMC vans with Ford Windstars. And then proceeded to drive the front wheel drive V6 soccer mom minivans like they were in the big GM ones. The amount of $$$ our branch spent at Ford dealer shops likely contributed to the need for company reorganization and eventually closure/buyout.....

I know of a company local that actually ended up going belly up and bankrupt because they choose Aerostar vans rather than G-series or Astro vans. They bought like 15 of them when Ford was making them and they all spent more time in the shop than they did working. No money to buy different vans, lost productivity and down the drain it goes. I have a former co-worker who told me this story and no reason to believe it was not true. It was a growing a/c and heat service company he had worked for. They went from F100 and C10 service trucks with service beds to mini vans trying to save money.

 

[L31MaxExpress]

What about gas? Does it run fine on 87?

The intake valve closing point is a little later than the factory camshaft. As a result it runs 87 more effictively than the factory cam. When you get out of CA and can get it tuned, it will tolerate a little more timing than the factory cam will.

 

[HotWheelsBurban]

I know of a company local that actually ended up going belly up and bankrupt because they choose Aerostar vans rather than G-series or Astro vans. They bought like 15 of them when Ford was making them and they all spent more time in the shop than they did working. No money to buy different vans, lost productivity and down the drain it goes. I have a former co-worker who told me this story.

The really ironic part about them buying the Windstars, is that the owner of the company also owned a bunch of Ford dealers...in Tennessee. They could get any of us a great deal on anything FoMoCo made....just didn't get a deal on the repairs.

 

[L31MaxExpress]

What about gas? Does it run fine on 87?

I'm new to this stuff, are there any downsides or concerns I'm not seeing?

The only downside I could see is if you start hammering on the thing with more power and the bottom end craps out on you. If you drive the truck like a sane person, I do not see any real downside. Just about any camshaft is better than what GM put in the L31 factory. It is really only good for grandma who wanted her Escalade to idle seamlessly smooth in the drive through. Having used the F-car LT1 or the GM factory 96 LT4 cam in several of these engines along with a Corvette/4.3L S10 converter I never understood why GM used the stock cam and converter they did in these trucks.

 

[Schurkey]

I was changing my timing chain and gears, and when I went to torque the bolts broke one of them of. I thought I was being gentle, going around doing just a little at a time, but still snapped the head off one of them. The others were stretched/deformed and look like they would be about to break. I tried to use an extractor kit, didn't work. The extractor just kept stripping out. I tried to weld a nut on the end of the broken bolt and apparently some of the weld got away from me and I ended up partially welding the broken bolt to the cam. I ground it down as much as I feel comfortable with and it's still fused. I don't know what else to do besides replace the cam at this point.

"I" would work harder at digging the broken bolt out. A die-grinder with a pointy rotary file (burr) would make short work of that weld. You may lose some threads in the cam. That's too bad but not a crisis.

The good and bad news is that I live in California, but I'll be moving to a no-smog state in about six months, but I'm also due for smog right now so whatever I get will have to pass on the stock tune...

It seems that my options are:
1) Junkyard stock cam, do the bare minimum just to get it back on the road for now and maybe upgrade later
2) New stock-spec cam
3) Mild aftermarket cam and risk opening up that Pandora's box on a truck that's already been running bad and fighting me every step of the way for months

4) Remove the broken bolt, use the cam you already have.

5) Get two Grade 8 hex-head bolts, or Grade 8+ socket-head cap screws (if there's room for the socket head inside the timing cover) of the correct length, diameter, and thread pitch, (5/16-18?) put the timing gear on with those two bolts AND PROPER TORQUE, using "Blue" threadlocker (Loctite 242 or equivalent). Or--what the heck--Loctite 271 "Red". Leave the third bolt broken. When you get past your emissions inspection, or you get to whatever Non-California-Nutjob state you intend to move to, put in the cam you really want. Yes, there's some risk with this process...

I read somewhere that it was 26# and did it with a 1/2" drive tq wrench. I know it was a dumb move to try and use a big wrench at it's minimum value

cam bolts are 18-20 ft-lbs. 1/2" torque wrench is a bit over kill imo. its possible they are out of calibration

'97 C/K service manual says 25 Newton/Meters (NM) or 18 ft/lbs. Damned metric stuff causing problems again.

A 1/2 torque wrench is absolutely the wrong tool to use for that. DO NOT TRUST A TORQUE WRENCH AT THE BOTTOM OF IT'S SCALE. But no torque wrench will "work" when you're using the wrong torque spec.

what about drilling it out and putting in a threaded insert? I've done it before

I'd do that before changing cams...but I don't think it's needed in this case.

Sounds more like I just over-did it using too high a spec on too big a wrench.

Yup.

The manufacturer claims +/- 3% accuracy. I bought Husky because they have a good warranty,

For years, it was "industry standard" for the lowest torque of a torque wrench to be 20% of the highest value.

A "100 ft/lb" torque wrench had a minimum torque of 20 ft/lbs.
A 150 ft/lb torque wrench had a minimum torque of 30 ft/lbs.
A 250 ft/lb torque wrench had a minimum torque of 50 ft/lbs.

Amazon is filled with torque wrenches that have a minimum value of only 10% instead of the previous standard of 20%. Torque wrenches tend to be the least accurate at the bottom of their range. The two things together--reduced bottom-of-scale, and reduced accuracy at bottom-of-scale, make for a potential accuracy disaster.

 

[boy&hisdogs]

"I" would work harder at digging the broken bolt out. A die-grinder with a pointy rotary file (burr) would make short work of that weld. You may lose some threads in the cam. That's too bad but not a crisis.


4) Remove the broken bolt, use the cam you already have.

5) Get two Grade 8 hex-head bolts, or Grade 8+ socket-head cap screws (if there's room for the socket head inside the timing cover) of the correct length, diameter, and thread pitch, (5/16-18?) put the timing gear on with those two bolts AND PROPER TORQUE, using "Blue" threadlocker (Loctite 242 or equivalent). Or--what the heck--Loctite 271 "Red". Leave the third bolt broken. When you get past your emissions inspection, or you get to whatever Non-California-Nutjob state you intend to move to, put in the cam you really want. Yes, there's some risk with this process...




'97 C/K service manual says 25 Newton/Meters (NM) or 18 ft/lbs. Damned metric stuff causing problems again.

A 1/2 torque wrench is absolutely the wrong tool to use for that. DO NOT TRUST A TORQUE WRENCH AT THE BOTTOM OF IT'S SCALE. But no torque wrench will "work" when you're using the wrong torque spec.


I'd do that before changing cams...but I don't think it's needed in this case.


Yup.


For years, it was "industry standard" for the lowest torque of a torque wrench to be 20% of the highest value.

A "100 ft/lb" torque wrench had a minimum torque of 20 ft/lbs.
A 150 ft/lb torque wrench had a minimum torque of 30 ft/lbs.
A 250 ft/lb torque wrench had a minimum torque of 50 ft/lbs.

Amazon is filled with torque wrenches that have a minimum value of only 10% instead of the previous standard of 20%. Torque wrenches tend to be the least accurate at the bottom of their range. The two things together--reduced bottom-of-scale, and reduced accuracy at bottom-of-scale, make for a potential accuracy disaster.

You make some great points, I think I got in too much of a rush in the heat of the moment thinking that I need a new cam right away. I am still interested in that 492 cam but I really should get it running right first before throwing modifications at it.

18 pounds is tough becuase my new wrech only goes down to 20, and my 1/4" goes up to 200 in pounds, which is only about 16.5 ft lbs. I guess it's going to have to be 16+ loctite then.

I think you're on to something with the die grinder, the welded portion is really only a fraction of the overall bolt circumference. I guess partial threads are better than no threads/bolt.

 

[L31MaxExpress]

You make some great points, I think I got in too much of a rush in the heat of the moment thinking that I need a new cam right away. I am still interested in that 492 cam but I really should get it running right first before throwing modifications at it.

18 pounds is tough becuase my new wrech only goes down to 20, and my 1/4" goes up to 200 in pounds, which is only about 16.5 ft lbs. I guess it's going to have to be 16+ loctite then.

I think you're on to something with the die grinder, the welded portion is really only a fraction of the overall bolt circumference. I guess partial threads are better than no threads/bolt.

Which is why I suggested a reverse drill bit. The start of the bolt holes are chamfered and you can probably use a slightly larger drill, catch the bolt and spin it out before damaging more than a thread or two.

 

[PlayingWithTBI]

Which is why I suggested a reverse drill bit. The start of the bolt holes are chamfered and you can probably use a slightly larger drill, catch the bolt and spin it out before damaging more than a thread or two.

Plus, a left hand drill bit won't bind on the threads like a right hand one will.

 

[Erik the Awful]

A 1/2 torque wrench is absolutely the wrong tool to use for that. DO NOT TRUST A TORQUE WRENCH AT THE BOTTOM OF IT'S SCALE.

+1
There's very little that I grab a torque wrench for. Lugnuts, internal engine bolts, and a few other things. Still, I own at least 5 torque wrenches of different sizes.