What am I doing wrong?

[frogman68]

Trying to finish the engine build (see http://forum.73-87chevytrucks.com/smforum/index.php?topic=10135.msg70425#msg70425 )
Yes its been a long time we are almost to the point of dropping it in.
Last weekend went to torque the cam bolts (20 ft lbs) set the torque wrench to 10 to start (using ARP bolts) get to the third bolt and it snapped.
I was mad thinking it was a bad bolt set, pulled it apart was able to walk it back out.
Today (didnt get new arp bolts) I got some grade 8 bolts (5/16 coarse 3/4 long with lock washer) again torquing to 10 ft lbs the same hole bolt snapped again (the other two will torque to 20 ft lbs)
Is it something with the cam ? (I did run a thread chaser thru before I did it today) I was able to walk this one out too.
Not sure if I should just buy a new came and be done with it or is it something I am doing wrong.

Thanks

[VileZambonie]

Did you measure the depth of the hole?

[beastie_3]

Just run the two bolts, dont need the third. JK

Very odd it is snapping at under 20 ftlb. I assume the bolt is going in all the way before you torque it.

[frogman68]

Did you measure the depth of the hole?

Yes its 1 inch , I measured it by putting the thread chaser in then marking it by the cam then pulled it out.

[frogman68]

Just run the two bolts, dont need the third. JK

Very odd it is snapping at under 20 ftlb. I assume the bolt is going in all the way before you torque it.

I thought of that but not with this engine, something funny about this went to Advance Auto before I started today to get some assembly lube the counter person didnt know what I was talking about he got the manager she tells me there is no such thing just put it in and run it when I finally found it she said she never heard of it.


Yes I am running the bolt down with a 1/4 inch drive ratchet I am getting about a half turn before it clicks for 10 ft lbs on the other two on this one I am going super slow to be sure

[VileZambonie]

What kind of torque wrench are you using? 240 in lb isn't a lot. Just use lock tight and goodntight it.

[frogman68]

What kind of torque wrench are you using? 240 in lb isn't a lot. Just use lock tight and goodntight it.

its a Craftsman , its breaking at 10 ft lbs I am thinking of doing what you said good old german torque but I am worried that there might be something wrong with the cam and do all this work and it blows up when I start it lol

[Dr_Snooz]

I am going super slow to be sure

Might be your problem. If the bolt is galling in the hole, either from a bad thread or from shmutz in the hole, going a little faster could get it past the point where it galls. Are they breaking in the same spot? What are you feeling in the wrench when they snap? Can you feel any binding? I had a trans case (aluminum) that kept breaking bolts just under 21 ft-lbs. Ran them in a little faster and it torqued just fine.

[frogman68]

I am going super slow to be sure

Might be your problem. If the bolt is galling in the hole, either from a bad thread or from shmutz in the hole, going a little faster could get it past the point where it galls. Are they breaking in the same spot? What are you feeling in the wrench when they snap? Can you feel any binding? I had a trans case (aluminum) that kept breaking bolts just under 21 ft-lbs. Ran them in a little faster and it torqued just fine.

No it seems fine till the last moment then it gets real easy . did not check if its the same spot the thread chase went in real easy