Porting templates

[mhr]

I am in the process of building a porting template for a 2.5 Mercury. The template would be made out of 1/8-inch thick aluminum and have the ports CNC machined. You would simply slip it in the bore and the deck would locate it. You could scribe all cylinders very quickly and very accurately. I was planning to make myself one using the much-posted John Marles 330 hp port map. If anyone else wanted one I could have a few made up, cost would be dependent on how many were interested.

If engine builders, professional or otherwise wanted a proprietary template to make their life easier I could have 1offs made with complete confidentiality.

The image shows my current design for the 330 hp template. The locating pins are not as good as a flange to set the depth, but they make it much easier to manufacture. If anyone has a better idea I am willing to listen.

Thanks
Mike Harris

[email protected]

[mhr]

Some of the information was left out of the posted map, and I don’t have a block in front of me to measure. Hopefully S&F members can help me fill in the blanks.

Do the 2 dimensions for the height of the exhaust port represent the oval top to the port?
Are the transfer ports centerlines 90º from the exhaust port centerline?
If not what is the distance between the exhaust ports and the transfer ports?
What is the total depth of the cylinder?
What is the web thickness between the boost ports?

I tried to post the largest image possible but it is still not the best if anyone wants a high-resolution image I can email it.

Any other thoughts on the map would be appreciated.

Thanks

Mike Harris
[email protected]

[Russ]

It would help more if you had a Drag sleeve in front of you to measure, in addition to your port map.

[Vector77]

Mike:
I would be intrested in one.

Bob Drye

[Superdave]

I made one for a Yamaha. I used a new sleeve and turned it down to slip inside the cylinder. Then cut the ports in the sleeve and used it as a guide. Same as yours, but most of the work was already done ;)
Dave

[Burke Kilgour]

I'm interested in the template. Did you get some done?
What do you figure for a price?

[Scream And Fly]

This post (http://forums.screamandfly.com/forums/showthread.php?s=&threadid=5314) includes a 330HP port map from John Marles (us1).

Greg

[Burke Kilgour]

Thanks Greg but I already have that saved to my computer, the aluminum template would be really nice for repeatability. I was going to cut one out myself, but rmh's would be CNC cut, and me (being lazy) would rather buy one........... :rolleyes:
:D

[stvhelm]

what compression is recommended to run the 330hp port map?With the templates, dont forget you need 2 of them. port and starboard. its also not recommended to grind on a nikasil sleeve. a renik job would be on order unless of course you do up a steel motor.

[Burke Kilgour]

Good question about the compression for the 330....... hmmmm
I'm building a steel bore 2.5, so theres no nic problems ;)

[us1]

I run mine at 180#

[Burke Kilgour]

John, how do you figure it would work with 145-150 #?

[us1]

I will work fine as long as the boat is not too heavy.

[Markus]

John, I remember that you run more than 25 degrees timing and 91 octane California pump gas. And now you are telling us that you are running 180 lbs compression as well. Are you running a really rich mixture, or are you not doing all three at the same time?

[us1]

I have 15 motors. They are all different. I only run 25 degrees timing and 145# on 91 octane. With trick heads you can get away with a little more.

[Burke Kilgour]

OK, now ya gotta explain "trick heads".................LOL ;)

[us1]

Just combustion chambers and squish angles.

[stvhelm]

I need me a set of those super duper angle cut heads. all i got now is my 30's.

[us1]

Send them over and tell me how many CCs you want.

[KMA1/4master]

Originally posted by mhr
I am in the process of building a porting template for a 2.5 Mercury. The template would be made out of 1/8-inch thick aluminum and have the ports CNC machined. You would simply slip it in the bore and the deck would locate it. You could scribe all cylinders very quickly and very accurately. I was planning to make myself one using the much-posted John Marles 330 hp port map. If anyone else wanted one I could have a few made up, cost would be dependent on how many were interested.

If engine builders, professional or otherwise wanted a proprietary template to make their life easier I could have 1offs made with complete confidentiality.

The image shows my current design for the 330 hp template. The locating pins are not as good as a flange to set the depth, but they make it much easier to manufacture. If anyone has a better idea I am willing to listen.

Thanks
Mike Harris

[email protected]

[KMA1/4master]

friggin EGGHEAD

[JTS Racing]

Port heights are great.....but what are the roof and wall angles that actually control where the charge goes when the door is opened :rolleyes:

[us1]

The stock angles will work fine for 330 HP.

[Burke Kilgour]

Which heads would be better, the top hat, or the hemi?......... for the 330 motor?

[rock]

mhr
I might be interested also. Post eta and cost or email me. Thanks
Rock

[us1]

Top Hats

[Raceman]

If you're locating by the deck height you're assuming that the block hasn't been decked. I think the closer you come to optimum porting the more critical the specs become. I guess production tolerances have never been a problem, but if you're gonna be real picky, seems like an adjustable dept dummy sleeve measured for placement with a dummy piston for degrees of crankshaft rotation would be the optimum setup.

[Firestarter]

Good point Raceman, you are gonna run into problems with deck height. Though I think most are gonna be ok.
As far as a flange, you could get a flanged sleave and turn it down like another did then CNC your port map into it.

I think you could get a blank flanged sleave from Federal.

RT

[Burke Kilgour]

Where's mhr? you'd figure he'd respond by now........... :confused: