13 replies to this topic

[boonas]

Hi,
I started building my 7 port engine and i m having a problem.
I fitted the ARP main bolts and a new mini spares center strap.
ARP bolts must have a tight torque 85lb according to the manual included and minispares center strap bolts have a tight torque of 65lb. i tight them according with this spec and my crank doesn't rotate. i change the arp studs and fitted the standard ones and tight them all with 65lb and the crank rotates excellent. there is no problem with the crank or anything else. i m sure is the difference on the tighting torque.
 how can i solve my problem since i want to fit the ARP bolts?

 

[Artful Dodger]

the crank should turn whatever torque you are putting on the bolts unless it is seriously excessive.  this means that there is a problem of you not having the right bearings, tha caps on the wrong way around or the wrong caps and the bore of the bearings being mismatched

 

take the bearing cap off and have a look at the bearing, doenst look scored or marked at all does it?  how hard is it to turn? do you have to grip it with your hands tightly to turn it or do you have to use tools. 

[mini13]

take the crank and shells out fit the caps, torque up and measure the main bores,

 

also tripple check that tourque setting.... are you torquing with lube? is it the arp lube?

 

can you measure bolt stretch rather than torque?

 

after a;; that you might need a line hone.

[boonas]

well there is a light mark on the side bearing.

well it turns a little bit by hand and then it stucks and needs tool?

 

you are sayng it  should turn whatever torque you are putting on the bolts unless it is seriously excessive.

20lb of difference isnt excessive? why when i fit 4 standard bolts and the 2 long of the centre strap and tight them all to 65lb crank rotates with no problem?

[Artful Dodger]

Any marks mean its pinching up, which isn't good

Do you know the cranks been ground? Have you fitted oversize bearings?



Well yeah it should turn, freely done up to the torque setting.

When torqued to 65lb, are you sure the caps are seated? Not getting thread bound or caught up on a dowel

[Earwax]

was the block / caps lined bored to ensure exact tolerance on the different centre main?  

i quickly looked at this kit from ARP   -206-5401  and founf torque of 80lbs  not 85 on the online instructions ( i actually thought it too high, based on ARP head stud torque usually being lower than factory settings .  

[Gr4h4m]

Strap distorting the centre main cap?

[Artful Dodger]

I'm going to be pointing out the obvious here..

But you have machined the centre cap down for the steel strap havnt you?

[Gr4h4m]

Time for some pics....

[ACDodd]

What are your bearing crush figures? Have you measured the bearing tunnels with the fasdteners torqued? What are the sizes?
What are the sizes of the main crank journals?

AC

[Ethel]

It does seem unlikely that amount of extra torque could compress & distort the block & cap.

 

By side bearing you mean the "thrust bearing"? Is there an alignment issue, what happens if you turn the strap round, are the ARP bolts a bit bigger diameter under the head?

 

Either way, I'd follow AC's advice and recheck the bearing tunnels etc, even if you can stop the bindings the clearances may well be too close.

[boonas]

well... I m using standard bearing. yes it has been mashined for the centre strap and yes I m using arp lupe. on the instructions in the kit says 85lb. I took the engine to the mashine shop today and he confirmed that bearings are the right ones crank is straight and he sagusted to tight and the arp studs to 65lb insteaded of 85lb. I will do this tomorrow.
the question now is: will it be safe since I will tight it lower than the recommended torque?

[boonas]

Eventually i tight them all (arp studs and minispares centre strap bolts) to 65lb. Crank rotates excellent, fitted the pistons too.... rotates very smooth.... Thanks for your help guys.

[boonas]

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