valve rocker and arm assembly

[madblkscientist]

Hi how are u doing and thanx in advance

I have very recently aquiered a 89 240sx with a ka24e single over head cam it was running and i was planning to turbocharge it until it stop working

it turns over it is getting gas then i did a compression test # 1 2 piston cambers had no pressure 3 had very little and 4 had like 180 so i taught dam gotta rebuild head until i relised that the valve roker assembly was lifting up as i rotated the engine.a couple of bolts the hold down the shaft was lifting up and down i tried tighening them but it was threaded out so my question is,

can i just remove the assembly and drill/tap a bigger bolt into it

what size is the original bolt

and what size higher can i go

when i took the plugs out and rotated the engine i think i felt i build up of pressure so maybe the valves are still good and i need only bolt the assembly down 100 percent

[seang]

If the threads are stripped you either have to drill and tap to a larger size, (if a larger hole wouldn't compromise the strength of the rocker shaft), or Heli-Coil them.

[Rev_D21]

I personally would see what a machine shop can do in this situation.

[wa-chiss]

Yes, you can drill out for a bigger hole, but you'll end up stripping the threads again. I don't know why but it seems they don't like torque after a lot of miles. All ten of the holes on my head have heli-coils in them. It doesn't take long to do but you do need a steady hand. IIRC the bolts are M10X1.25 but don't quote me on that. You can go to the hardware store with one of the bols and get it sized and also get a heli-coil set for the bolt size you have.

Just use the recomended drill size to drill the hole bigger,Use the tap included with the kit,insert heli-coil in the hole,and re-assemble rocker assembly to the factory torque specs.

Heli-coils acually add strength to the threads. Most manufacturers acually use thread inserts on aluminum parts that see high torque items like block to head mounting holes. So, you can only gain when you use heli-coils.

[madblkscientist]

where can i order the heli coils from im in miami,florida

[seang]

Heli-coils are available at lots of places over the counter

[madblkscientist]

like

[seang]

I think Napa has them

[madblkscientist]

I think Napa has them

ok gonna check 2mmorow

[madblkscientist]

ok the exh valves on cylinder 1 n 2 r leaking it wont hold compression and when i blow compressed air tru the spark plug hole it goes str8 into the exh

[seang]

It might have burned exhaust valves from someone beating the crap out of it.

[madblkscientist]

im in

It might have burned exhaust valves from someone beating the crap out of it.

im in the process of pulling the engine out to rebuild it now i gotta find a good rebuild kit that has everything minus pistons+rods

and 1 with pistons and rodsams has a kit but its pricey and those pistons look like low comp pistons

i wanna bump the compression up and run low boost for shi*s n giggles then imma take it off bcuz imma ship it 2 the islands

so any info will help on setups n such

[wa-chiss]

it might be hard to find them, but NISMO has a set of high compression pistons for the SOHC. Something like 11:1 CR.