Manifold Studs - Size and thread count (1 Viewer)

[dv_fj40]

Fixing an exhaust leak that developed between the header and head, I stripped out the threads on one of the manifold studs (goes into the head). Thinking I could purchase a longer stud and go that route - it continue with the thread destruction (stripping).

Does anyone know the proper Helicoal kit to get as to fix this problem? Or, what size this stud is as with thread count.

I have a 1976 FJ40 2F engine. The stud that stripped is the one below the carburetor.

And lastly, reviewing this board and other websites, I notice there is about a 50/50 consensus on using one or two gaskets when you have headers. I read the postings back on this board going back to October 2003, and again, it is about a 50/50 consensus. Is it more of a preference?

Thanks,
Joel Briggs

 

[IDave]

Don't know the thread size offhand. It is the same as the bolts with 14mm heads.

I'll comment on the header/gasket issue, however.

Not a matter of preference. We'd all prefer to buy fewer gaskets. Headers differ in their fit, often in thickness. One piece are harder to match to the head than two piece. Some particular styles (MAF 6>1) have a worse tolerance than others. So. Two gaskets will work where one will not sometimes.

 

[offcamber40]

I cant remember the thread count or size either.. when I had my head rebuilt I pulled all the studs and went down to the local hardware store and matched them up (took the old ones with me) and bought som longer ones. I run a header as well, and the extended studs helped to mount it with a second gasket. This fixed all my exhaust manifold leaks! Good luck. Quick question, did you strip the threads on the stud, or the threads in the head? If you just stripped the bolt threads and not the head, just put some vice grips or something similar on the stud and back it out of the head and replace.. no need for a helecoil on that type of repair!

Mike

 

[Ian Rogers]

Thinking I could purchase a longer stud and go that route - it continue with the thread destruction (stripping).

you need to be carfull trying to put in a longer stud as the stud will hit back of the hole. and on a car like a VW crack the head. Lucky for you the f head is built like a rock.

 

[offcamber40]

Actually, you can buy studs that are the same length as stock for the head side of the stud, then longer for the threaded/nut side.. thats what I did w/ no probs.

Mike

 

[miletwo]

It's a 12mm thread, and I believe the pitch is either .25 or .30. You can either use studs if you can find them, or a 1-1/4 bolt would work in a pinch as well. I did some exhaust manifold triage on my pig when I bought it last weekend up in Seattle. The parts store we did the work near had a bin with the bolts but no studs. I used a few bolts to get me on the road and it worked okay. I'd stick with studs if I were you though. It's easier to hang the manifold gasket on the studs and then slip the header/manifold in place.

Another thought... might just take one of your old studs with you when you go to the parts store. Find the 12mm studs and make sure the pitch of your old stud matches the new ones.

 

[bustanutley]

I have this same problem. My brother installed the MAF headers and the POS never sealed, still don't, I ended up striping one of the holes as well, and i got pissed and just left it. I think the headers are warped or were tweaked from the factory. I'm not really sure what to do other that get 2 piece headers

 

[dv_fj40]

I stripped out the stud hole on the head block. I notice McMaster Carr carries:
M12 Thread Size, 1.25 & 1.75 Pitch.

I will do what you suggested and take the stud to the hardware store to determine its size and pitch.

Thanks,
Joel Briggs

 

[65swb45]

Early thru 8/66 [F135] 10mm x 1.5

67-73 [F145 and F155] = 10mm x 1.25

74 only [f155] stepped stud

75-87 [2F] = 12mm x 1.25

As far as the gasket situation goes, I stay away from all the Kevlar junk, and go with a single, steel-faced header gasket that has a 1/4' crush sleeve around all the exhaust ports, increasing the likelihood that it can and will deform to match the surface irregularities of the header. And I use coppercoat.

 

[dv_fj40]

65swb45,
Ever out in Death Valley, look me up. Will have a cold one for you. (this applies to all of you.) Thanks for the information!!! I really appreciate it.

Now to fix my stripped stud hole!!!

Joel Briggs
www.desertdrifter.com

 

[miletwo]

hehehe... he said "stud hole"

 

[cruiserbrett]

Early thru 8/66 [F135] 10mm x 1.5

67-73 [F145 and F155] = 10mm x 1.25

74 only [f155] stepped stud

75-87 [2F] = 12mm x 1.25

As far as the gasket situation goes, I stay away from all the Kevlar junk, and go with a single, steel-faced header gasket that has a 1/4' crush sleeve around all the exhaust ports, increasing the likelihood that it can and will deform to match the surface irregularities of the header. And I use coppercoat.

I agree on the steel faced gasket. I have used with great luck, the Felpro intake/exhaust gasket...

My 74 F motor does not have stepped studs...and other 74's I have seen also do not.