Machining and port grinding ,playing around machining. Please post your pics!

**Zoomba** · 01-30-2018, 01:11 AM

Playing with my 150 2.5 block. Trying to machine it to 225 Pro Max tuning configuration. Set the milling machine head at 30’ angle to match the v of the cylinder, used a long ball end mill to cut the rod slots to expose the fingerports. Mercury cuts this in the ProMax block. It really opens up the fingerports. You can see up them now in the pic.

I am going to play around with my die grinder and round all the edges of my cuts.

I used the end mill to cut the casting slag off the rod slots.

Next I’m going to flip the block over, and cut the exhaust chest. The lower hp engines have straight cut exhaust chest exits to the exhaust. The 200 Super Mag I built last season had angle cuts to make more of a smooth airflow exit. I think I am going to use the all nose of the end mill to roughing the cuts, then smooth with my die grinder.

Not quite as radical as this shot.

If I had a CNC mill, I could just program the x and z axis angle move and cut it in one operation. This is more like whittling.

Milling machine speeds it up. But you can also destroy things faster if it goes badly.

Going to raise the exhaust ports to about 1.60, and widen the sleeves out to the width of the casting of the port, and clean the fingerports aluminum casting out.

Looking for a strong 250 hp @ 6500-7000 rpms.

**Scream And Fly** · 01-30-2018, 01:53 AM

Looks like really nice work! Please keep the photos coming. These types of posts are the best.

Thanks for posting!
Greg

**tux974** · 01-30-2018, 05:33 AM

Looking good!

That exhaust chest looks so nice not sure I would get it dirty by running it......

**Dave S** · 01-30-2018, 12:06 PM

Looks good. When I do rod slots , just bolt to exhaust side and drop the mill in.

**FORBESAUTO** · 01-30-2018, 03:53 PM

That chest sho is purty, looks mighty familiar though.

**Mrzip** · 01-30-2018, 04:07 PM

.... Nice

**Zoomba** · 01-30-2018, 07:14 PM

Originally Posted by FORBESAUTO

That chest sho is purty, looks mighty familiar though.

Yeah, think ot is a pic of yours...just popped ot up there for an example.

Think Im going to cut mine about 1/3rd of the way between ports. The shiny one looks a bit more hi rpm than I want.

**FORBESAUTO** · 01-30-2018, 08:10 PM

Wasn't calling ya out or nothing, knew you hadn't cut yours yet and was using that old pig for an example. I would cut your exits on the port pockets at 30 degree angles. I always blend and smooth mine, but I think on next one I'm gonna blend a little past the angle cut but leave a little edge at the end to stop the flow from sticking to the floor and help it "jump" over the next port a little. Just a thought. I've used both a ball mill and an end mill cutting out the centers. I actually think I like the end mill better, also removing some of the wall in center. The end mill makes for a little more flow and causes the space between ports to be more flat.
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**Zoomba** · 01-30-2018, 08:59 PM

Originally Posted by FORBESAUTO

Wasn't calling ya out or nothing, knew you hadn't cut yours yet and was using that old pig for an example. I would cut your exits on the port pockets at 30 degree angles. I always blend and smooth mine, but I think on next one I'm gonna blend a little past the angle cut but leave a little edge at the end to stop the flow from sticking to the floor and help it "jump" over the next port a little. Just a thought. I've used both a ball mill and an end mill cutting out the centers. I actually think I like the end mill better, also removing some of the wall in center. The end mill makes for a little more flow and causes the space between ports to be more flat.
.

Appreciate the help, and the pix. Was very much hoping to get all involved to post pix, as so much tribal knowlege out here on our group. Like your suggestion. I think that I agree that leaving a little flat on the wall may help separate the individual cylinder pulses. Been wanting to play with this for years, and finall got tooled up. Fun stuff, and my last build screams!

I used this portmap, from James Perry.

Trying to get all this hotrod stuff in one thread, pretty standard stuff, but spread all over the site. Wonder if Greg could put together a sticky of syandard performance tweaks?

Going to cut the heads to 34cc from 38, about .080" , and try CCMs new intake stuffers instead of cutting the front half.

**Zoomba** · 01-30-2018, 09:10 PM

Here is a pic of my Mag200 EFI that I cleaned up woth a Makita 1/4"shaft die grinder and a carbide burr

**Zoomba** · 01-30-2018, 09:19 PM

Last years build, 200 EFI w die grinder and carbide burr work

**Zoomba** · 01-30-2018, 09:20 PM

You can also see the fingerports have had the mismatched casting cut.

**FORBESAUTO** · 01-30-2018, 10:48 PM

Get you some epoxy and fill in the oil pump void, remove the bushing in floor of cylinder and fill in so it can't fall out, and fill pump hole in front half to equalize cc volume on cylinder 2. Also fill the ledge on the front half with epoxy. I also fill in the ditches on half in the reed openings on front half.