Head retensioning

Submitted: Monday, Mar 17, 2003 at 12:14

ThreadID: 3890 Views:2071 Replies:6 FollowUps:4

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Gerry

There appears to be two trains of thought when it comes to retensioning the head on your vehicle. I have recently recon'd my GQ petrol donk and it's almost time to check the head tension. Here's the problem...
1. Do I simply run over it with the tension wrench (in order of course) to make sure they're all OK, or...
2. Do I back each stud off a bit and then retension to the correct setting, doing each one in turn?
I just want to make sure that whatever I do is the correct way to go for my vehicle.
Cheers

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Reply By: Truckster - Monday, Mar 17, 2003 at 12:20

Monday, Mar 17, 2003 at 12:20

1.. The way I did it on all my race bikes. little diff to a car, but same principal...

2.. Why would you back them off?? incase they are too tight maybe? that could be a good thing..

Id be interested to hear how this one ends up..

what does the engine reconditioning place say?

AnswerID: 15361

Follow Up By: Gerry - Monday, Mar 17, 2003 at 12:30

Monday, Mar 17, 2003 at 12:30

Not sure Truckster - maybe to break the seal on the thread or bolt head?? The engine re-con mob don't know either as they are "not mechanics and only know about machining stuff". Looked around on the web but couldn't find much. Let's hope there's a good mechanic or two on the forum eh?

FollowupID: 9355

Reply By: crfan - Monday, Mar 17, 2003 at 13:33

Monday, Mar 17, 2003 at 13:33

You have to back off the head bolts before retentioning to get a proper tention .But most head gaskets now are mono torque and dont need re tentioning.

AnswerID: 15367

Reply By: Ferret - Monday, Mar 17, 2003 at 17:01

Monday, Mar 17, 2003 at 17:01

How many k's did you get out of your donk...why the rebuild?

AnswerID: 15379

Follow Up By: Gerry - Monday, Mar 17, 2003 at 17:29

Monday, Mar 17, 2003 at 17:29

312,000 k's. I tow an off-road van most places and have done a lot of fairly hard sand driving. It's also on LPG.

Power was dropping off and economy getting worse (if that's possible with a GQ). A compression test indicated worn rings and as it turned out, the head had a hairline crack. I must say though that it used no oil whatever and whilst it needed a rebore, the crankshaft was still in perfect condition. The camshaft was starting to show wear on a couple of lobes as were the followers. All in all, quite surprised at the overall condition for the mileage. Should get lots more out of the ol' girl yet.
Cheers

FollowupID: 9363

Follow Up By: Ferret - Monday, Mar 17, 2003 at 18:31

Monday, Mar 17, 2003 at 18:31

Can I ask what the recon cost? My 95 (on gas) is still in good nick after 262,000 so I'm just wondering what i'll be up for when the time comes. I've just bought it and had a comp. test done before hand. They were between 1020kpa and 1050kpa versus a spec of 880kpa to 1080kpa so not to bad.

FollowupID: 9367

Follow Up By: Gerry - Wednesday, Mar 19, 2003 at 13:16

Wednesday, Mar 19, 2003 at 13:16

Hi Ferret - this is already in the archives, this forum certainly is popular...
Overall cost was $3800 but this included rebore, new pistons & rings, linish crank and new mains & big ends, grind camshaft (standard), face the lifters, new cam bearings, repair head (pressure test, weld crack plus remove ALL steel gallery plugs and weld up the holes - this is where they always crack, 12 new valves and 6 new stellite seats), face head, face block, full balance from the harmonic balancer through to the pressure plate, supply all gaskets, new timing chain and tensioners etc. I also had the machine shop reassemble the short motor (rings pistons, cam, crank) but I put all the timing gear, sump, head etc back myself and of course put the motor back in myself as well.

Hope that gives you some idea. Cheers mate

FollowupID: 9460

Reply By: ThePublican - Monday, Mar 17, 2003 at 18:38

Monday, Mar 17, 2003 at 18:38

Used to be that a retension was done at 500 Miles after head work,motor hot,whip off the tappet cover,retension,cover back on and off you went,, holden , valiant ect,different story with ford from early 70s when introduced monotorque head gaskets for the "cleveland" V8.

AnswerID: 15388

Reply By: kezza - Monday, Mar 17, 2003 at 23:42

Monday, Mar 17, 2003 at 23:42

Quite simply if you used a monotorque head gasket - no need at all to re tension, if you used anything else the publican has got your answer.
If you dont know what you used - you will pay more attention next time hey (go back to where you bought it and find out)

cheers

Kezza

AnswerID: 15443

Reply By: Eric - Tuesday, Mar 18, 2003 at 00:11

Tuesday, Mar 18, 2003 at 00:11

Gerry.
Your original specification for the tension on the studs will say xyz with oiled threads, the reason you back them of is to allow the oil which will have escapped from the contact piont of the threads to relubricate the threads. If you did not oil the threads you must remove the studs one at a time and oil them , a very common cause of gasket failure is lack of oil or clenliness of the thread giving a false tension reading ie to low that is why most pro engine builders use a protracter to determin the correct tension. Eric.

AnswerID: 15450