Tapping cylinder head!
Turbo Mini Forums

Hi,

Had a heater control valve blocked off on the end of my cylinder head and went to replace it today with a blanking plate.

Fitted the blanking plate and was bolting it down - bolts got to the surface of the blanking plate but didnt tighten, just kept spinning.

So I took those bolts out (the where originally bolting the heater valve down) to find the bottom of them had stripped!

Ok so I ran down some new stainless bolts and the same happened, only this time the threads in the cylinder head have stipped!! :(

What do I do now? Ive got the vernier down the holes and theyre both M6 holes.

Will I have to try an imperial tap? As id have to drill to 7mm and use an 8mm tap wouldn't I otherwise?

Bit depressing - car's ready for the MOT now, was just looking to tidy a few bits up and its screwed me over lol

Cheers

yes use a 6.8 mm drill and use a M8 tap and open the holes out on the plate

job done

I'd maybe try a 6.5mm drill, remember cast iron is soft as sh1t!

Ok i'll try it cheers lads.

I've managed to get the bolts up quite tight by packing them out with some washers - made a new gasket and lots of sealant seems to be holding out.

Will take the head off and do it proper on a pillar drill after the MOT.

no need to take the head off, just use a hand drill
as tom says a 6.5 mm drill will give more thread in there

Edited by BENROSS on 24th Jun, 2008.

M6 helicoil kit no good for this? is the cast too soft?

Hi,
I'd have thought a Helicoil would have sorted it...
Cheers,
Gavin :)

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My Mini build diary

The original thread would have been 1/4" UNF - that's why it stripped.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I rekon its cheaper and probably easier just to drill them out and re-tap them 8mm like the chaps say.

Ive got the taps here if you wanna borrow them. Mmmmmmmmmmmmmmmm.

Edited by Ben. on 24th Jun, 2008.

Build Thread Click Here

Just looked and we have s**t loads of 1/4 UNF helicoils, so you can use them if you want.

The choice is yours.

Build Thread Click Here

Edited by richminiturbo. on 24th Jun, 2008.

Tapping 8mm is fucking sacrilidge. If you are to tap it a bigger diameter be so smart to use 5/16UNF. I hat those mm/imperial mismatchers wankers!

Edited by Ben. on 25th Jun, 2008.

Build Thread Click Here

I know, it's my job!

If Ben has got some 1/4 UNF helicoils you may aswel heli coil them.

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www.fusionfabs.co.uk



1/4mile in 13.2sec @ 111 terminal on 15psi

Vegard you really can be a self righteous mother fucker sometimes.

LMAO

I agree with V 100% on this, why start mixing threads when everything else will be AF

Thank you Tom, I appreciate it, really!

However, I'm not a metric/imperial-swapper-cunt!

Why not do it properly? Helicoil is the proper solution here.

i agree with both tom and vegard

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"