alexands

The thread on head nuts reminded me of my issue. My machinist just got my block, head, and crank done yesterday. He balanced all rotating assemblies and everything. He did so with the old rod nuts. I was under the impression you should never re-use them. When questioned he said put two drops of Loctite on them and they will be OK. BTW: He does many Porsche engines for the local shops around DFW, so he's got some experience with these cars.

What do you guys think? Should this be OK?

tommo951

Well if you are going to use locktite why not just get the mig out and weld them properly.......
only joking. Do you really want to trust your rebuild to what could be a potential weak link in the chain? When I am building engines for race or performance, if I am re-using the roads I always take 10thou off the caps and reline bore the complete big end bearing housing. I also do the same with the main bearing caps. What is the point in having a crank knife enged if it is going to run tight in its caps? In essence what I am saying is don't sink the ship for the lack of a coat of paint. You don't need to go to the extent of buying race hardware but new OEM would be a distinct benefit. You can locktite those as well if you are not going to lock wire them.

Matthew West

My understanding is that you should replace them AND use loctite.

hosrom_951

Here is a tip, replace them with the raceware kit (?)

The stocks ones are plastic? I read that they are in the 911&Porsche World Magazine.

Since the bottom end rods are critical, go and upgrade the rod bolts.....i would.....

Ski

I've always replaced them and NEVER used loctite, torque to spec. IIRC the only loctite used or specified is blue medium on the rotor screw(just a dab'l do you), red loctite, high strength, on new factory head studs and ARP studs - (Raceware specifies pipe dope), and loctite 574 on the girdle, oil pump, and balance shaft covers. Of course, experience and past proven history for trusted people and what they have done is up to you.

alexands

Thanks for all of the input. My only hesitation to just picking up new ones is that the motor has already been balanced and I don't want to throw anything off. So, maybe the question I should be asking is - if I replace the nuts how much do you think it will affect the balance job?

adrial

Nuts I do not think would effect the balance job at all.

Factory rod bolts definetely are not plastic...
I have never seen loctite recommended for rod nuts. ARP recommends their assembly lube on the bolts, thats it.

ARP recommended red, high strength loctite for the head studs I bought from EBS.

hosrom_951

Adrial: That is why i said "The stocks ones are plastic? I read that they are in the 911&Porsche World Magazine" coz i KNOW that it couldn't be

Laust Pedersen

Plastic?
In engineering terms you distinguish between plastic and elastic deformation.

Plastic deformation is a permanent deformation (such as a stretch bolt) and elastic deformation is a reversible deformation (like a spring used within its design limits). Maybe that was the reference rather that a material description.

If the stress on a part at any spatial point exceeds its Yield Strength (material property) then that region will be plastically deformed.

… Compare changing the nuts to knife-edging the crank, which certainly affects the local dynamic balance a lot more.

Laust