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10 minutes ago, stillp said:

OK, sorry for my nit-picking, I used to do it for a living!

Pete

School nit nurse Pete ??

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On 11/13/2020 at 6:35 PM, BlueTR3A-5EKT said:

Maxpeeding rods enclosed instruction leaflet mention 45 ft lbs torque using ARP lube - what is this and where is it obtained.

What torque have others used and what process? 

 

Some measurements of what we have - The Maxpeeding con rods all come in at 658 grms each.  (about 2/3 the weight of original lightened con rods)

The lightened and balanced original TR4A con rod set we have, that were done by Osselli, weigh 940 grms each. 

The Power Max 87 mm pistons come in at 660 grms each.

Cheers

Peter W

https://www.highliftmedia.com/big-end-bolts-torquestretch-guide-how-to/

Lots of information here.  I don't know how the stretch gauge works they talk about - maybe it is just a rotation indicator based on the pitch of the thread ?  Looking at the chart, for our bolts  3/8" X 24 TPI  you can use stretch figures OR torque figures (32ft lb) which is close to the Maxspeedingrods figure of 45 ftlbs  Of course we don't know what material they have used.

Bob

Edited by Lebro
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1 hour ago, Lebro said:

https://www.highliftmedia.com/big-end-bolts-torquestretch-guide-how-to/

Lots of information here.  I don't know how the stretch gauge works they talk about - matbe it is just a rtation indicator based on the pitch of the thread ?  Looking at the chart, for our bolts  5/16" X 1.5"  you can use stretch figures OR torque figures (32ft lb) which is close to the Maxspeedingrods figure of 28 ftlbs  Of course we don't know what material they have used.

Bob

Thank you Bob for that link. Now I understand

I feel an hour in the workshop due to make one of these.

Peter W

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Edited by BlueTR3A-5EKT
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I see, you would need access to the bottom of the bolt, ok for con rods but no good for head bolts. I will check on the pitch of our bolts, & calculate how much to turn it (once slack is taken out) to achieve the required stretch, while noting the torque being applied, & stopping if it exceeds 30 ftlb

Edited by Lebro
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When I worked as a civil engineer using HSFG bolts we preferred either Load Indicating Bolts (LIB), LI washers or the part turn method for accurately measuring the clamping force of the bolts. So in this instance I’d opt for the part turn method. 

Rgds Ian

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OK, so the Maxspeeding rods for our cars use 3/8" UNF ARP 2000 bolts, which according to both the instructions which came with them, & a table found on here :

https://www.highliftmedia.com/big-end-bolts-torquestretch-guide-how-to/

should be stretched by 5½ to 6 thou. The pitch of a 3/8"UNF bolt is 0.041667", so divide that by say 5.8 thou gives 7.18391  divide 360 by 7.18391 gives 50°  so follow the instructions in the link above, then rotate the head by 50° to get the required stretch.

Bob.

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On 11/13/2020 at 6:35 PM, BlueTR3A-5EKT said:

Some measurements of what we have - The Maxpeeding con rods all come in at 658 grms each.  (about 2/3 the weight of original lightened con rods)

The lightened and balanced original TR4A con rod set we have, that were done by Osselli, weigh 940 grms each. 

The Power Max 87 mm pistons come in at 660 grms each.

Cheers

Peter W

For information, I have just been weighing & balancing pistons & conrods.

Pistons (87mm from TR shop) 674 to 678 g, now all 674 (metal taken from the base to equalise)

Conrods (Maxspeedingrods) all 650 g  nothing to do.

Bob.

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Are they standard shape pistons Bob ? Or something a bit more special ?

Edited by Hamish
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