im so confused
i m new to this whol thing and i really need to know how to find the torque sequence for the heads on a big block chevy. can anybody help me. :confused:
http://www.hotrodsforsale.com/hrfs/t..._big_block.htm Couldn't find a diagram for you but as I recall you can tighten up all bolts to about 40 or 45 ft.lbs. then go around proper torque sequence (center outwards) then re-torque at 60ft.lbs., then do it again at 80 ft.lbs. A torque wrench that you can set the torque and it clicks when you get to the setting works best if you have one!
Here's a rough diagram, for a 1970 454.
For any head, you start as close to the center of the head as possible on one side then go as straight across as possible for the next bolt. Then you can go either forward or to the back for the third, usually on the same side as the last bolt tightened (#2). Work in a circular pattern -- something like this:
9 5 1 4 8
10 6 2 3 7 11
Number of bolts doesn't matter. It's like this on all engines -- fours, sixes, straight eights. You wouldn't want to start with #2 then go over to #3 in the above example though. If you started with #2, the next bolt would be #1, then #3, #5, #4, #7, #6, #8, #11, #9, and finally #10. It's best to use 2-3 increments as suggested. If the torque is 70 or less I generally use two steps -- set it in the middle for the first round, then all the way for the second round using the same sequence both times. For 80-100 I go with three steps. Start with 40, split the difference from 40 to final, the final.
Clicker wrneches are nice -- as long as they are properly calibrated. NEVER store one "loaded" -- always set to zero before storing. Otherwise the springs have tension on them for a long time and can take a "set", which throws off accuracy.
The old beam style wrenches are actually more accurate. You can bend the pointer to zero to "reset" it, or just subtract/add whatever the pointer is on from/to the desired torque. The only thing you can mess up is not watching the needle as you tighten. If you're off a couple ft/lbs it won't matter.
NEVER use your torque wrench to break bolts loose! That's hard on it, and can throw it out of calibration.
Clicker and dial type wrenches need to be calibrated every couple years or so. If you only occasionally need one, buy a cheap clicker every time you start an engine project. The cheap ones don't hold up well over time, but are generally good for a year or two before getting out enough to need recalibrating. If you paid $30-$40 for the thing, it will cost that much (or more) to get it recalibrated. So just toss the old one and get a new one! That's just fine for the hobbyist who may build an engine every 2 years or more. The wrench should last for installing brackets, new head gaskets, etc. between builds. If you build more than one engine a year, you're probably better off to get a nice torque wrench and have it calibrated per the manufacturers suggestion. Expect to pay $80+ for one though, then another $25-$50 for clibration. Of course beam types don't have to be calibrated, are pretty cheap, and last a long time if taken care of. Unless you bend a beam wrench or the scale, it should last almost indefinitely. So don't bang it around! I always thought the beam types looked cheap and a bit hokey, until I bought a couple clickers and paid to get one recalibrated...
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