20 replies to this topic

[bluemini1979]

When redrilling the block and gearbox to take 5/16 unf bolts is there a kit of the bolts and washers available. if not what bolts do people use?

thanks

[Ivor Badger]

You have to use cap screws in many of the holes, especially the front. There is not enough clearance for hex heads. Makes it a real pain getting the in and out, but if needs must.

[Cooperman]

Why would you go to the trouble of doing this?

Most really modified and ultra high-revving Minis don't have this done and have no gearbox to block interface problems.

[bluemini1979]

It was suggested and was looking into it before committing

[tiger99]

The only reason I can imagine is stripped threads, which are best repaired by fitting helicoils.

[Spider]

It's really not at all needed.

[The Principal]

This may help -

 

http://www.minispeed...-516-allen-cap/

 

 

http://www.theminifo...e-bolts-to-516/

[Ethel]

It's in the Vizard 'bible'as a mod to counter leaks from block flexure. I reckon you'd have more to worry about if you put that much stress on you engine.

[Cooperman]

It's in the Vizard 'bible'as a mod to counter leaks from block flexure. I reckon you'd have more to worry about if you put that much stress on you engine.

Maybe it applies to engines revving at 7500 rpm+.

I've never had any problems with engines that rev to 7000.

A better mod might be to Heli-Coil all the holes at 1/4" UNF and use higher-tensile steel bolts with, say, 20% increase in torque figure.

I still think it's unnecessary and a lot of work for nowt.

[Dusky]

My dads track mini has no problems with oil leaks. Rev limit set at 8.5k.
Standard fixing

Edited by Dusky, 30 December 2015 - 02:52 PM.

[Ethel]

I can't remember if it was just a pre A+ thing. Certainly more for stroked cranks and very high revs. I recall we had a rather techie topic on it once that pointed the finger at the centre main bearing web. I think I'd be inclined to reach for the RTV Silicone and torque it up in two phases if I was concerned.

[mad mk1]

I don't think there is any need,

I just make sure the gearbox face is nice, I use 1/4 bolts all round.

Never had a leak with my 200+ Bhp and Rev it to 8k on the strip.

Just get some 12.5 cap head bolts.

[bluemini1979]

Thanks. I won't be spending my time doing it then. Only wondered as It had been suggested and its in the vizard book. Spend my time polishing the shell instead then

[Spider]

It's in the Vizard 'bible'as a mod to counter leaks from block flexure. I reckon you'd have more to worry about if you put that much stress on you engine.

 

I have great admiration for David, but on this, his advice is incorrect.

 

<Edit: If I recall, it was in his first book 'How to Modify Your Mini', but wasn't in his later books>

Edited by Moke Spider, 30 December 2015 - 06:37 PM.

[1968andyf]

Could vizard have meant as a mod for the thin flange early s blocks