Block modification for k series starter clearance

[PACR]

I need to modify a standard k series block to clear the starter. I have the original block as a template and can make a guide up from card to allow me to check I am replicating the modification before bolting everything except the starter together or breaking into anything important.

What’s the best method for removing the aluminium with normal tools (no milling machines etc in my garage)? Before I attack it with an angle grinder if there a best way to do it and using what? My thoughts were to make cuts in the ribs down to a marked line then angle cut to nip the material out. I think it’s easier to cut Ali with a thin disk than grind out (from memory grinding Ali can bung up a disc quickly) so I want to leave minimum grinding.

Thanks, Piers

[rj]

I'd probably try a flap disc

[p.mole1]

I used an abrasive wheel on a dremel at high speed and it removed the metal quite quickly and made a nice neat job. Also I used a Wosp starter so I only took off the bare minimum.

[SLR No.77]

If you have access to a bellhousing, or can remove the current one from the car if the engine's already out, bolt it up to the block so you can repeatedly grind the new block and trial fit the starter, it makes the job much quicker. I've used rotary cutters in a drill, a Dremel is a little small for the job. You'll be surprised how much metal you need to remove.

Stu.

[revilla]

I have done a few now and always used a bellhousing as Stu suggests. I've always used an angle grinder. Just keep it moving, don't dig in. Just wipe it over the surface taking a later off at a time, keep checking with the bellhousing and starter, keep going until you've got 1mm or so clearance all around (slip a bit of card between the block and starter and check it's not pinched) and don't take off more than you need to up at the top where then engine number is stamped to avoid breaking through into the head bolt channel / oilway. As long as you keep checking the fit and stop removing metal once you're just clear, you won't have a problem. There is quite a lot of metal to take out and despite its reputation it's actually pretty hard so even an aggressive grinder disk will take it back slowly enough to be able to keep it under control. I've usually used a spiraband on a Dremel just to tidy things off when finished.

[revilla]

A few pictures of one I did in case it helps. Pictures are in time order so show the process as it progressed:

 

[PACR]

It looks like splitting the bell housing from the gearbox and checking it’s the actual starter may be less time consuming and more accurate than playing about with a template. I hope my neighbours don’t mind a bit of angle grinding on a bank holiday! Thanks.

[rj]

It shouldn't take long enough to annoy the neighbours unless just /one/ bark from a dog is enough.

I think, first time I did it, some 15 years ago, it took less than an hour albeit with an XXXXXL Dremel.

[revilla]

One other thing to mention. It makes a mess. If you use a die grinder it's like aluminium flakes, if you use an angle grinder it's more like aluminium sand. Either way it's not something you want inside your engine. It also seems to spread it far and wide, so do it somewhere where it won't contaminate all the boxes of parts you're about to use to build the engine up and somewhere where it easy to clean up or where it doesn't matter. Also, if the head is off I would mask off the whole of the top deck of the block and any open holes with gaffer tape. Just make sure you remove any residue afterwards with solvent. The one in my pictures is one of the first ones I did and just packing out the cylinder liners like that wasn't good enough, I ended up splitting the block again and pressure washing everything afterwards.

[rj]

And wear eye protection. Don't ask me why I know it's painfull to have an aluminium-flake in the eye overnight.

[SLR No.77]

My personal opinion is that a grinder is too aggressive, even though it’s cast aluminium it’s a soft metal and lower speed cutting is more appropriate. I used the same type of cutter that I’d use for head porting, basically a spiral cutter in a variable speed drill - the shavings that are produced are pretty contained compared to using a grinder!

Stu.

[Jonathan Kay]

It also seems to spread it far and wide, so do it somewhere where it won't contaminate all the boxes of parts you're about to use to build the engine up and somewhere where it easy to clean up or where it doesn't matter.

And wear eye protection. Don't ask me why I know it's painfull to have an aluminium-flake in the eye overnight.

Thanks both for bringing up the safety aspects. Aluminium powder and fragments have a collection of hazardous properties: they're ignitable, *reactive, abrasive and electrically conductive.

Any good guides, please?

Thanks

Jonathan

* And I strongly recommend the thermite reaction for creating an interest in chemistry.

[Bricol]

I just used a 40 grit flap disk in an angle grinder - keep it moving and don't stick on one area too long so it doens't clog.  If it does, swop to another

Unlikely to have any ignition problems, electrical problems, or toxity problems if you do it somewhere sensible - like in a garage or outside.   If you huddle up with in the airing cupboard you might . . .

[rj]

Well Jonathan,

Whilst I appreciate that aluminium actually /can/ burn it takes a lot to make it do so. Mind you I used to be a fireman and am more than average paranoid when it comes to putting things to fire. You'd have to behave more than just silly to get into trouble on that account.

But OK, if you manage to do so, then you are in really deep s**t as you can only put it out using sand.

 

[7 wonders of the world]

slow speed burr in a die grinder with the hoover noozle zip tied around the grinder body with the end over the burr so the majority is collected at source.