BGA Head gaskets

[Staggard]

I have clocked 500 miles after a top end rebuild before the car went in to the painters, I now have the car back and decided to tighten the heads down today and was surprised how loose the bolts were, each bolt/nut went down a further 3/4 of a turn. I don't know if anyone else has experienced this but I would recommend if using these gaskets to do the first re torque at 200 mls and then twice more before you get to the 1000 mls. Just an opinion of course. Graham

[stagmuffin]

did you back them off a tad before re torqueing ? bet it was nice to get out and drive it again after so long away from the wheel

[Staggard]

did you back them off a tad before re torqueing ? bet it was nice to get out and drive it again after so long away from the wheel

I certainly did ole bean, yea its good to give the old girl a run ( I am taking the car next time) Shot down the TF1 but I thought I had better back off at 6500-7000 till I tighten down the heads. Anyway what are you doing up ?? any self respecting geeza would be in bed with a mother of a hangover

[richardthestag]

yes I had the same

[DJT]

Hi Graham,

When I did mine, I ran the engine for a while, then re-torqued them the following morning. After about 300 miles I did them again and got about half a flat on most of the nuts and bolts. Checked again at 500 miles and all tight.

[1959terry]

did you back them off a tad before re torqueing ?

Can someone please explain why you would need to back them off before re torquing? I was an apprentice marine engineer many years ago and i was never taught to back them off so I assume it must be a new thing.

Terry

[GDPR]

It's to avoid any effects of static friction on the threads/nuts/bolt heads/washers - you have confirmed that they can move. You can mistake a stuck nut with a correctly torqued one....

[Staggard]

Can someone please explain why you would need to back them off before re torquing? I was an apprentice marine engineer many years ago and i was never taught to back them off so I assume it must be a new thing.

Terry

To make sure that the bolts/studs/nuts are free to turn. Not a new thing in my book Terry I was taught to toque heads in this manner back in the 60's.

[Staggard]

Ole Russie quick off the blocks tonight

[Motorsport Micky]

Because a standing nut has a degree of "stiction" to overcome the friction of nut on stud before a torque can accurately be read off.

When torqueing the final "operation" should be in one motion (preferably no more than about 20lb fts range) so that the nut travels evenly without jerking and comes to it's pre determined torque setting where the wrench "clicks off" or if using a beam type wrench the arrow indicator comes up to the indicated torque on the scale required. If tightening an already tightened nut slack off the nut by no more than half a flat and than apply the torque in a smooth motion to again apply the required torque.

If you use a pre set torque wrench ie a click off type and you make a mistake when setting the torque maybe going over the amount by a small amount, DON'T just turn the wrench back to the required torque.
The threads used in a torque wrench may well have a small machining allowance called backlash, the difference between the male and female thread forms and pitch. The wrench WILL be accurate if the torque is set in the direction of the increasing readings (going up the scale, this is the way the wrench has been marked and calibrated).If you need to reset a torque wrench rewind the wrench at least 20lbs ft below the torque required and then again increase the reading on the guage in one smooth movement up to the required setting. Then the wrench is set for being used for torqueing.
There are digital read out gauges which go between the nut and the wrench (Machine Mart sell some for about £35 as I remember) which can be used, and of course being digital on a read off a lot of the mechanical sympathy as itemised above is taken care of for you, however you still need to apply the torque in the method itemised.

Alternatively check e bay P1010228.jpg and buy an Acratork torque wrench calibration gauge to allow you to check your wrenches are accurate. I bought mine 30 years ago and have checked all my wrenches on it crosschecking the Acratork guage when I've bought any new wrench ie new 40-220lbft Torque wrench check the Acratork against it at about half range reading (where it's most accurate) at 110lb ft. The Acratork is consistently within 2lb which is the calibration limit for the wrenches normally.

Micky

[1959terry]

Thanks guys, you learn something ever day

[Motorsport Micky]

Whoops ...beaten to it by everybody, SWMBO explained to me that not to wash the dishes NOW would involve me in an disproportionate amount of pain and suffering lol,

Micky

[Knockwurst]

Should there be washers fitted to the bolts and studs? When I stripped my engine, only the bolts had washers

Simon

[DJT]

Should there be washers fitted to the bolts and studs? When I stripped my engine, only the bolts had washers

Simon

Washers should be fitted under the nuts also. A total of 10 for each head.

[Staggard]

Whoops ...beaten to it by everybody, SWMBO explained to me that not to wash the dishes NOW would involve me in an disproportionate amount of pain and suffering lol,

Micky

OOOOh I do love a good torture.