[gomowgto]

I'm getting ready to reinstall my timing cover on my 67 GTO 400 engine, and the 67 service manual says 30 ft lbs for the 4 bolts and the 2 stud nuts. It says 15 ft lbs for the timing cover to intake manifold bolt where the rubber washer is.
Butler performance says 35 ft lbs for the 4 bolts and 2 nuts, and 10 ft lbs for the timing cover to intake manifold. Why are they different?

[Kenth]

I prefer the torque specs from Pontiac service manuals.
Examples from 1966, 1969 and 1978 Service Manuals below.

[Sirrotica]

FWIW, as many timing covers as I've put on Pontiac Stratostreak engines that was one torque spec I've never used, and zero problems having never torqued them other than, tight enough.

If you ever watched an engine being assembled in a factory, the machine used is set at a specific torque reading before it is used to assemble thousands of bolts/studs. It won't be torqueing the same rate when set initially until it is recalibrated at a later time. As long as you tighten in a criss cross pattern, and at an equal rate, I don't believe the difference in torque specs is going to make any measurable difference on a timing cover installation.

After years of tightening bolts most mechanics don't feel the need to torque each and every bolt we touch, we can tell from feel when it's tight enough.

Case in point, a friend of mine that had a father that was a mechanic for years assembled his rebuilt 390 ford with just a ratchet and a breaker bar, no torque wrench was used on anything. The end result was a ford 390 that ran very well, and ran fine until he wrecked the car in a ditch. That didn't have anything to do with what the nuts, and bolts holding the car together, It was the nut holding onto the steering wheel that caused the wreck.......

[Goatracer1]

Chances are that your torque wrench is off by 5 lbs/ft anyway.

[geeteeohguy]

What Brad said. I've never used a torque wrench on a timing cover or water pump. Never had any issues. You don't want to crack the cover or crush the gasket. Just tight enough.