Jump to content

ST170 crankshaft main bearing torque


MarkBzero
 Share

Recommended Posts

Hi,

I have looked on the internet and I am getting different results.

Does anyone know the torque setting when fitting ERA sump to ST170? I have to undo 4 main cap bolts to fit the windage tray.

Any help appreciated.

Thanks Mark

Link to comment
Share on other sites

Hi Mark,

Detalis from LOCOSTBUILDERS.CO.UK

These tightening values are for standard bolts in a us focus svt, the engine is identical to the st170 lump.
Main bearing cap bolts

Stage 1: 25 Nm
Stage 2: 60 degrees

Connecting rod bearing cap bolts

Stage 1: 35 Nm
Stage 2: 90 degrees
 

  • Like 1
Link to comment
Share on other sites

I am coming at this from zero knowledge of this engine, but it seems odd that the conrod bolts are far tighter than the mains bolts, or is that all to do with different stretch properties?

Just interested.

 

Link to comment
Share on other sites

Your main end bolts are typically much bigger though, plus they're not getting flung around at several thousand rpm :) I would just suspect the loading on the rods is higher than the crank caps, but that's just my FingerInTheAir-o-meter working rather than anything quantifiably backed up by science :D

Link to comment
Share on other sites

9 hours ago, brumster said:

Your main end bolts are typically much bigger though, plus they're not getting flung around at several thousand rpm :) I would just suspect the loading on the rods is higher than the crank caps, but that's just my FingerInTheAir-o-meter working rather than anything quantifiably backed up by science :D

I agree, plus the Conrod is only 2 small bolts versus 10 for main end bolts and much larger. 

I will try on the weekend and follow Tiger Racing instructions I have a calibrated torque wrench. What could possibly go wrong.....famous last words.

Link to comment
Share on other sites

4 hours ago, Bob Tucker said:

The settings are 32 ft lbs big end bolts, and 65ft lbs mains studs.

I am guessing you're saying that for the fact the mains studs seem higher than the big end bolts but do you not have instructions on 2 or 3-stage angle-based tightening *after* that inital torque setting?

Link to comment
Share on other sites

A bit off topic now, so I'll leave the thread for the OP's st170 question after this.

Thats the final figure. I tighten in 3 equal (ish) steps, finishing up at 32 and 65.

But I stress they are ARP non-stretch bolts/studs, so no direct comparison for stretch bolts.

The rod end bolts torque figure  seems crazily low, but this is the 4th redtop ive built, all using ARP rod bolts.

One was even designed for 8k rpm with forged rods, & is still running strong (right Kevin?)

https://tech.arp-bolts.com/instructions/109-6001.pdf

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...