Head torque and base gasket sealing

[rd400canuck]

Hi guys,

I am currently disassembling the top end so I can check right end gap and have a peek after it ran for 3 minutes for the first time (cyl walls and piston look perfect) and I noticed the a couple sides of the base gaskets had oil on them. I'm not sure if that happened when i was taking stuff apart... things were defo wet in there because its rich right now.

Is 15 ft/lbs really correct for those headbolts on the RD400 ?  I only ask because when torquing them I remember thinking "that's all? doesnt feel like much". Mind you, my torque wrench is long and perhaps the leverage made it feel that way.

Is it safe to go higher if I feel the need?

[SUPERTUNE]

Too low, even I think if I remember 16 ft-lbs is stock.
No less than 22 ft lbs. On my rebuilds I use 24 ft-lb.
Exception: Is the RD350 still using the crappy ring gaskets. 17 is max for them unless you do the 400 headgasket conversion.
Chuck

[JB Weld]

I was torquing heads on my 350 today and was shocked the Haynes said 15 ft/lbs. I had one side snugged more than that!

[SUPERTUNE]

If you go any higher than 17 ft-lbs on RD350 with ring gasket... I have found they have major headgasket leak due to the bolt pattern outboard of the ring gasket, so it just bows the head and leaks worse!
With a RD400 or a 350 with milled decks using the full RD400 headgasket that is not a problem.
Chuck

[JB Weld]

I've had that problem before. Not sure if my old torque wrench just wouldn't go that low, or calibration was way off, but that's when I started using the Permatex Ultra Black. Haven't considered machining yet.

[Czakky]

FWIW I always had to add permatex to RD350 head gaskets even when torqued properly....

[Dvsrd]

I've had that problem before. Not sure if my old torque wrench just wouldn't go that low, or calibration was way off, but that's when I started using the Permatex Ultra Black. Haven't considered machining yet.

FWIW, I prefer to use 3/8" drive (i.e small) torque wrenches when I work on bikes. I believe they are more precise when it comes to low torque values, than a larger one at the absolute bottom of its range. So I have one that covers 5-25 Nm (M5 to M8, basically) and another one that covers 20 to 110 Nm (M8 to M14 bolts, approx.)

[SUPERTUNE]

Most of the guys here don't understand newton meters...
In the USA we are accustomed to Foot-Pounds (ft-lbs)
C

[JB Weld]

Before I thought to look up torque specs, or ordered parts to get my RD back on the road, I bought a new 1/4" drive torque wrench with in/lbs and n/m figuring it would be appropriate. I don't trust my old torque wrench for more than tightening the lug nuts on my truck.

Fast forward back to this past Saturday. Looked in the Haynes and saw 15 ft/lbs for the heads and proceeded to torque them to 15 in/lbs! 

Time to buy another torque wrench!

[Dvsrd]

In any case, whether using Nm or lbsft, factory recommendations or higher torque, one major factor is dry or lubed, hardened washers or softer washers, and even type of lube used. And if lubing threads only, vs lube under the fastener head as well. That is just as important as the torque value used.