stripped cylinder head bolts

[Bregg23]

taking off the cylinder head to replace the top end gaskets I came across 3 stripped bolts. Talking about just putting studs in now? was wondering anyone elses input. Or if they have come across this as well and what they have done or any other suggestions/ideas for this issue.
thanks

[CJM]

Which bolts are you referring to?

-The studs that go into the cylinder itself

-The head bolts themselves

-The small 6mm diameter rocker cover bolts.

If its the studs your SOL and will need to have HD ones installed.

If its the head bolts then there is a chance you might be able to clean up the threads, helicoil or timesert them.

If its the rocker cover bolts you can retap them for a slightly larger size or helicoil them.

Worst case is you wind up like a friend of mine who went thru something similar-we eventually just got an entire topend.

It is VERY important you torque the bolts properly. Cylinder Head/Valve
cylinder head cover bolt -- 8 lbf-ft
rocker arm shaft -- 20 lbf-ft
intake sub-rocker arm shaft -- 20 lbf-ft
exhaust sub-rocker arm shaft -- 20 lbf-ft
cam sprocket bolt -- 14 lbf-ft
cam tensioner plug -- 2.9 lbf-ft
cylinder head nut -- 33 lbf-ft


Cylinder/Piston
cylinder bolt -- 33 lbf-ft
cylinder stud bolt -- 33 lbf-ft

[Bregg23]

it is the 6mm bolts, but my biggest concern is the long 6mm bolt that is on the right side that goes along the backside of the cam bearing, its probably about 6 inches long. my first thought was to helicoil, but we also are pondering the idea of just replacing it by turning them all into studs.

also thanks for the guide on all of the torque specs, i just wish the guy who had it before me knew what the hell he was doing....... to bad its too late to pass that information on to him....

[CJM]

You could retap them to a slightly larger size, 1/4" is just slightly larger than the 6mm bolts.

If you helicoil then it will be even larger. Id do 1/4 first, that dont work then its helicoil time.

Those 6mm bolts I torque by hand, they dont need anymore than that. I use a 1/4 drive ratchet and choke up on the head and just snug them up good.

[bostthehause]

Hey CJM, I also have pulled the threads out of my head for several of the 6mm valve cover bolts. I plan to drill and retap the holes to 1/4". Exactly what size tap do I need to buy? I read a thread a while ago that said the tap needs to be 1/4" 28. Should the tap be NC (Course Thread) or NF (Fine Thread)?

[CJM]

Really depends on the bolts your using. 1/4x20 would probably be what you should use. 6mm is just a hair under 1/4 inch @ .23" iirc, 1/4 is of course .25"

When I did my friends we went up to 7mm and had no issues. After having it apart like 5x using the wrong torque specs (we misread and thought they were supposed to be 33 ft-lbs like the head studs) and other issues we went up to 8mm-but 8mm is to big to work with the valve cover gasket.

Try 1/4x20, Id go to lowes if your buying local for the bolts. Home depot wont have ones that are long enough, but home depot will have the tap and the drill bit to use.

Also watch out for the size of the bolt head. On some spots it might be to large and you may want to find an allen head bolt.

[bostthehause]

Thanks for the info bro! What about NC (Course Thread) or NF (Fine Thread)? Which one should I use. I'm assuming course thread but thought I would ask just to make sure.

[CJM]

Id just use course, gonna be harder to find the tap and the bolts for fine.