Torque-ing the cam caps

Ok - since my 'unfortunate incident' of saturday night I've been brooding over the cam caps torque issue.

I'm fearful that I may have damaged other threads by relying on my torque wrench instead of common sense. I don't think I have but there's a degree of 'confusion' when torquing down against the valve spring pressure I think.
Normal rules of 'feeling it bite' don't seem to apply.

I've a good mind to sideline the torque wrench after I've helicoiled the damage hole (hopefuly only one..) - any views ?

J

 

Best thing I could tell you is to run a thread chaser (not a tap, don't cut new threads) down each hole to clean up the threads you have. Then if you don't trust your torque wrench, rent one from an auto parts store. Or go buy a new one, what else are you going to do with your current torque wrench that you don't trust?

 

Well this is the odd thing - when i tested it clamped into the vice and hung some weights off it - it checked out OK. As mentioned I'm thinking I was confused by the resistance caused by the valve springs - Torquing up teh head bolts 7ft.lbs then 15ft.lbs went fine..



J

 

Interesting,on my 700 there was a point at which the cams were not engaging any of the valves,mwhich is how I got my cam retainers back on, that and adding a little torque to each individual bolt until they were all torqued correctly.

 

I saw a person on another forum that mentioned using bar clamps to pull down each cam against the valve pressure and then be able to install the caps without any spring pressure to stress the bolts or hole threads. He does this even when taking the caps off so as not to have any stress on the ever smaller amount of thread. No sure if this can work on an XJ. There would need to be a safe gap or opening on the head to be able to use to clamp onto.

Here is the link:

http://www.kzrider.com/forum/2-engine/2 ... que#645194

Best idea I've seen in awhile.

 

Thanks - this has opened my eyes.

@bighankshank - unfortunately there is no 'all closed' point on the cams I think so inevitably there'll be pressure.

I think I can also own up to yet more stupidity. Clymer says roughly line up the dot then tighten in a criss-cross pattern from centre, With dot aligned number 2 inlet is full open. so mucho pressure on #1 cap. I was tightening in a criss coss but ratcheting down too much at a time i think and thus not spreading the load effectively.

some way of relieving the spring pressure would be ideal and it looks do-able on the exhaust side with a clamp - not so easy on the inlet though. however netx time I'll go steadier.

Nice way to learn huh ? :roll:

 

Yeah, I think next time I have head work to do I will try it as well. Only thing to be concerned is to make sure whatever you are clamping on that counters the cam side is strong enough to handle the load. Definitely would want to watch not to damage any fins or anything. But it looks promising.