Filler block and thread inserts

[christophe]

Hi folks,

The threads of my filler block (OHV 6) are badly damaged. I'm just about using Heli-Coil thread inserts to fix it. I'd like to know if there is no problem to use that technique on that part, as it is made of a very light zamac.

Have a nice day.

[r1lark]

Christophe,

I have used heli-coils in the filler block numerous times with no problems. Just make sure you get the holes drilled/tapped straight.

[Kurt]

Same here. I have had good luck with helicoils. In fact my 51 has one in its filler block. I did that in 2005 and it is holding fine.

[christophe]

Thank you very much boys.
I'll do it that way.

[N8N]

If the block is the same as the V-8s the holes are blind so you need a bottoming helicoil tap

what I would do in that situation is to drill/tap the holes as per normal then cut the end off your helicoil tap with a cutoff wheel, then retap. et voila. you'll have to buy a new helicoil kit next time you go to to this but then you will have the regular tap and a homemade bottoming tap.

Also FYI at least the V-8 filler blocks are notorious for warping and also pulling around the bolt holes... standard repair for this is to hammer them pretty close to straight on a metal surface (the anvil on your bench vice?) also chamfer the bolt holes slightly (irrelevant if you're going to Helicoil all of them) and then finish with some wet/dry sandpaper on a piece of glass. do not overtorque the timing cover bolts and also use some Permatex no. 2 on both sides of the gasket around the filler block for a leak free installation.

good luck

nate

[christophe]

Thanks Nate.

I'll check that point too. They should have chosen another kind of alloy for that part. It's too light and, moreover, ages very bad.

Nice week-end to all of you.

[PackardV8]

also use some Permatex no. 2 on both sides of the gasket around the filler block for a leak free installation.

Nate, don't do that again! Just typing "leak-free installation" on the SDC site as if it were a possibility can cause a catastrophic collision of matter and anti-matter which could destroy the universe.

jack vines

[skyway]

CASO fix.

Drill the bolt holes all the way through, tap new threads, and epoxy bolts in place from the rear.

Onetime fix, and you just use nuts and lockwashers from the front.

[cliffh]

Using through bolts as Skyway suggests sounds like a great idea. The nuts could be tightened to a higher torque and get a better seal. Anyone think of a reason to not do this?

Cliff

[PackardV8]

The nuts could be tightened to a higher torque and get a better seal. Anyone think of a reason to not do this?

Yes, if the existing thread area is stripped or loose, getting more thread area for studs in the crap material of the filler block is a good CASO idea.

No, tighening to a higher torque is NOT. Overtorqueing is what damaged the threads in the first place.

Maybe, we should understand it is the gasket and sealant, installed on a clean, straight, flat pan rail which provides the seal. Tighening to a higher torque just distorts the pan rail and squeezes out the gasket and sealant. The new generation GM engine gaskets have metal reinforcements around the bolt holes which prevent the bolts from bending the pan/intake/rocker cover should the bolts be overtightened.

jack vines

[cliffh]

Most of the suggestions I've seen for installing the bolts into the filler block is to stay well below the factory torque settings and use enough gasket sealer to keep it from leaking. I was thinking that with the through bolts acting as studs, a reasonable amount of additional torque could be applied to the nuts. With Skyway's idea of a bolt threaded through the filler block from the inside and the head of the bolt up tight against the inside of the filler block, there shouldn't be much stress on the threads in the filler block itself. IIRC, the timing cover gasket is a thin paper gasket which would give less opportunity to distort the timing cover or the filler block.

[christophe]

Thanks for your input boys.

Like Skyway, I've thought also to install new studs and epoxied bolts. But, as this bloody part seems to be made of lardonium, I think that overtightening must be avoided. Anyway, I don't think that the pan rail can be distorted, as long as you don't forget to use the reinforcement. Oddily, this reinforcement was not used on the V8. The filler block threads would be long gone before distorting that 1/8 '' thick part. I think I'll use good sealer and torque reasonably and gently, if possible.