5/16 to 3/8 exh man studs on 340

[crash340]

Team,
I have an issue with the rear left exhaust manifold stud, was broken off some years back, drilled it out, easi-out wouldnt budge it, drilled it, tried to tap out the remainder etc. no go. So now I'm left with upgrading to a 3/8 stud, looks like it will fit ok, will fit through the TTI header flange no problems.

Question is, is there an issue in upgrading from 5/16 to a 3/8 stud??

Greg

[hemiken]

Greg, why do you not just put a Heli-Coil in the damaged oversized thread to bring it back to 5/16 stud buddy ?

[hemiken]

And if you are doing the furthurest studs on each end of the heads that hold the pipes on, weather you are replacing with a bolt or stud, this area needs to have some form of sealant on it as the holes on each end of the head go in to water passages and will leak if not sealed with a sealant.

[crash340]

Yeah, thought about Helicoil, would have to go and buy a kit, then there is a sealing issue with them, I have 3/8 taps and studs, provided the head can take it figured I would just run it up to 3/8, the header flange is larger than 3/8 so thats no issue, nut room is ok.

[hemiken]

Helicoil will not leak in that location if you are adding sealant also buddy, you have to think about spanner room also buddy.

[Chryco Psycho]

Helicoil can be tough to seal into water , even with sealant , there are timeserts which work better , tapping out to 3/8 is another option also ,  you may have to open the flange hole slightly to fit the stud through , you can use a Coupling nut which is approx. 4 x as long if clearance is a problem

[crash340]

Thanks for your input Kenny and CP, appreciate it.

im thinking I'll just go to 3/8, its not worth spending $50 on an insert kit, the TTI flanges are well over 3/8 hole diam and I have nut room etc, if the nut issue becomes a problem, I can always turn a 5/16 thread on the 3/8 stud. I may still do that yet, will only take a min to do.

Greg

[hemiken]

You could buy some extractor bolts that have a smaller head too if that is the case of using larger bolts

[dpcd67]

No problem with tapping that hole out to a 3/8ths and drilling the header flange. That would not work with the inside holes; not enough room for the nuts or bolt heads but you know that.

[crash340]

I did it last weekend, no problems, TTI flange is already larger than 3/8 from factory so all good, plenty of room for the nut as well., all good.

thanks everyone