Torque to yeild bolts and thread repairs

[Jay Smith]

Good afternoon all,
I wanted to touch base with some information and problems I seemed to be paliged with last week. I built a 225X this week from Ca. this motor had failure on #5 after going through the motor I find water in the lower half of the motor taking out #5 piston, rod, and crank... I found a blowed O ring on #5 assuming that was the cause of failure . Long story made short , there were 10 stripped female threads on heads and 1 stripped on the top main case bolt.. I built a 280 today and found 7 of these head bolts to have the shorter full thread like a 2.5-2.4 head bolts with short 3/4" helicoils installed . Friends these will not hold a head in place . I have used with 99% success for at least 15 years a thread repair called Time Sert they are a full length incert and come in custom lengths . I use the part number 03817 it is 3/8-16 X 1".200" long and works perfect on my thread repairs. My "guess" is that people are using the poundage + the 90 degree torque method even on a bolt that's been already torqued. and pulling threads on the motors. I have NEVER stripped a head bolt stud ( that wasn't already messed up ) by torqueing to a maximum of 35 FT lbs. and calling it goods...

Others may do this different with success BUT this is and the products that works for me for 20 + years ...

Peace,
Jay

[90 5.0]

Time serts are far superior for sure , in a pinch you can stack heli coils and cut the excess off the top.

This is actually why the bottom coil has the cut out in it for stacking them and knocking the hook off of the top one(s) for full bolt penetration.

I do 35ft lbs on heads also

[dwilfong]

I was going to ask what you all torque your heads to when using orings and studs.
Thanks for the info......................

[patchesII]

If you're torquing nuts on fine thread studs you can go to 28. I always torque my head bolts to 35 on o ring heads

[Carter Powell]

I have been using Time Sert thread inserts for over thirty years and there is nothing will even begin to compare with them.

Carter Powell

[texasvector]

If you're torquing nuts on fine thread studs you can go to 28. I always torque my head bolts to 35 on o ring heads

this is interesting.....ive seen SS studs stretch trying to get the fine thread nut to 35lb

[dwilfong]

I have Dorman grade 8 studs. 3/8-16 both ends. so 35 lbs?

[1BadAction]

this is interesting.....ive seen SS studs stretch trying to get the fine thread nut to 35lb

At the same tq value, fine thread bolts/studs have more clamping force than their coarse thread counterpart. 28 with a fine thread is likely the same or slightly more than a coarse thread at 35. The material (grade 5, 8, SS, etc) also changes this.

[David - WI]

A properly installed 3/8-16 x 3/4" long (2x the diameter) helicoil in A356-T6 cast aluminum (Merc block) is stronger than an ARP 2000-series (220Ksi) head bolt that size.

[gmacrae]

Hey guys, bringing this old thread back to clarify my own head re-install next week.

(rookie question incoming!)

I understand many re-use the original bolts (and I don't wanna drag that debate out!), I'm replacing the bolts because they're cheap and the old ones are ugly as hell... So to be clear - Jay's method of 35ftlbs (in 3 steps) definitely sounds the safest way to do it, but this does still apply to brand new (ie. unstretched) bolts? (installed with some light oil)?

Also, stock bolts are zinc coated grade 8, correct? Can't see any grade on mine... I'll raid the machine shop, rather than the merc catalogue

[Dave Strong]

35lb/ft is fine on new bolts you will not stretch the bolts and will have no sealing issues. Use a fine wire brush like a gun cleaning brush to clean the threads in the block, light oil on the bolt threads bolt heads and washers.

Dave