conrod bolt torque

[ThomasSwiss]

After an accident I checked the conrod  bearings (from Renault R4). 
I am looking now the right torque for the UNF 5/16 conrod Bolt number: SA 24120 E
the engine was rebuild in the 90's

[Ian Williams]

35 ft lbs should be right on these.

[Bob Culver]

General readers please note the above reply is very specific to the particular brand of bolt, and not applicable to common moderately ht bolts original equipment (and if not fatigued by running loose, or by a myriad tightenings to fit bearings, or stretched by over tightening. entirely adequate to non astranomic revs and at torques akin those for common ht hardware. many similar revving cars with much heavier pistons and longer strokes get by with non exotic 5/16 bolts))

[andrew34ruby]

I tighten them till they feel right. Never had a problem.

[John Mason]

I am with Andy “until they feel right” As an old mechanic who did his apprenticeship in the early 50’S once said to me, “Tight is tight.” Owners with engines for competition may wish to be a bit more specific.

John Mason.

[Ray White]

When our cars were built the average garage would not even have a torque wrench. In the same way, ignition timing would have been done by ear. (When it starts to pink back off a bit). Tyres were changed by hand and mechanics would be found down an inspection pit because hydraulic ramps were few and far between. How things have moved on! These days everything is computerised and I for one couldn't get a job in a garage now.!

[Charles P]

That conrod bolt looks like a modern design from the 12 point drive and lettering - the sort that ARP and others manufacture.
The legendary calibrated wrist of an old time mechanic is probably not the best way to fit them in my opinion, hence Ian's specificity 

Charles

[Martin Baker]

Absolutely agree with Charles.
If these are ARP bolts, they are designed to be torqued to give a specified degree of stretch. See https://arp-bolts.com/. Hence they are normally only supposed to be used 2/3 times before replacement. Phoenix and Hadley recommend 35 ft lbs for their con rods. Remember ARP bolts are very expensive - as I understand about 20% of the price of the complete rod!

[ThomasSwiss]

Thanks  Ian, 35 ft lbs is a lot, scares me

Thomas

[Robert Leigh]

I have been watching this thread with interest, not having an answer to offer, but I am still wondering what conrod has 5/16 UNF threads for the bolts; it can't be A7 nor Renault 4 I would have thought.