Turning torque for new engine

[fred cook]

Just curious, what amount of torque is (typically) needed to rotate a newly built engine that is still on the stand? I have the long block assembled for my 3.3SS that I am building and it seems to take between 30 and 35 ft lbs as measured with a torque wrench to turn the engine. This is with both cams installed, timed and all rockers adjusted. Of course, this is a new engine that has never been started yet. Has anyone else ever measured this?

[fred cook]

Forgot to add, spark plugs are not installed.

[Lapkritis]

Hmm... didn't measure mine that I just did but I'm sure someone here can tell. Did you use assembly lube and confirm the cams weren't binding? Cams should turn by hand on the sprocket without a ratchet or lever to assist. You would normally have plenty of turns on them from the timing procedure. With all the valve springs to compress, 30-35 is probably pretty close.

[roblav]

Sounds about right. Cams, rockers, and valve springs add a lot.

[fred cook]

Originally Posted by Lapkritis

Hmm... didn't measure mine that I just did but I'm sure someone here can tell. Did you use assembly lube and confirm the cams weren't binding? Cams should turn by hand on the sprocket without a ratchet or lever to assist. You would normally have plenty of turns on them from the timing procedure. With all the valve springs to compress, 30-35 is probably pretty close.

Yes, I used generous amounts of assembly lube. After installing the head/cam box assembly, I checked the cam movement. Both cams turned freely, could turn them by grasping the front end of the cam even without the sprocket attached. The turning torque is probably somewhat less than the amount needed to overcome the initial friction. Don't really have a good way to measure that as it would be difficult to turn the torque wrench and adjust it at the same time!

[Sapientoni]

I have a 4 litre BOP aluminum V8 engine that's hooked to a 914 tranny and uses the Porsche starter. When hot (overheating development) it seemed to be struggling with turning the engine. I put a torque wrench on it. Cold it took 60 lbs., hot the same 60 lbs. Plugs in and before and after running. Conclusion, starter losing it when hot.

[SchnellSchweitz]

With new Ps & Cs and all the spark plugs hooked up it was very hard to turn mine. I'd say I had to put 80 lbs of weight behind mine to get it to rotate.

Once in the car, I still have to put it in gear to rotate it. That's why I wish someone would come up with a ratchet that could reach down to the crank and turn it. I'm amazed when I hear people can turn their engines just by pushing on the fan belt. Especially, after a fresh rebuild.

[fred cook]

I finished putting the last spark plugs in the twin plug engine and decided to see what amount of pressure it took to turn it bottled up. Using my 1/2" Craftsman "click" type torque wrench, it required a setting of between 30 and 35 ft/lbs to rotate the crankshaft with the bottom plugs still out. With all of the spark plugs in place, it requires between 60 and 65 ft/lbs to turn. As the crank is turning, I can feel and hear the compression build and then leak down for each cylinder. All 6 seem to require about the same pressure to rotate thru. This engine has 10:1 Mahle pistons and the Porsche 964 cams. So, the compression is not but about 7 tenths of a point over the stock pistons and the cams are just a little hotter than the SC cams.

[SchnellSchweitz]

Sounds similar to my ft-lbs for torque. I may have overstated mine a little. I think mine is closer to 70 lbs to turn it over. But you're in the same boat as me when you get it in the car. 1st gear and a lot of pushing to get it to turn when you need to line it up for timing. :-)

[Mike_72]

I am loosing sleep over my engine right now, takes a ton of torque to get it first moving and then I would estimate about 35 ft/lbs to keep it rolling over with no plugs in. If I stop for a minute and then try to get it rolling over again I will have to heave on it pretty good and then it drops back down to about 35 ft/lbs again. This is an 2.2T that has sat for close to 10 years. Borescoped the cylinders found no rust on any of them. Sprayed wd40 in each as well. Does this seem normal or should I dig deeper?