Hey, Porter! (porting a 200 head)

[edgewood bronco]

I've started porting a head for my bronco! So far, I'm eight hours in. About 30 minutes of that was straightening the burr when I dropped the drill and bent it 5 minutes in to my day... Ugh...
I've basically worn out a carbide burr (eastwood part no. 11951). My forearms are sore, I've got a stiff neck, and I'm absolutely filthy - I look like a raccoon from the dust rings on my face due to goggles and a respirator - but what fun to open up one of these heads and imagine how much better it's going to breathe. So far, I've just done the inside passages - not the combustion chamber, trying to smooth things out and get rid of some of the restrictions as best as I can.
I've got a question concerning the combustion chamber side:
How much do I take out from the wall on the deepest part of the combustion chamber? Obviously, more clearance between the open valve and the wall will help it will breathe better, but it also reduces compression ratio. Can anybody with experience in this area offer some advice?
Also, What kind of burrs and other abrasives do you recommend? I'm fairly pleased with the above - mentioned burr, but was wondering if others had other suggestions and sources.
Thanks!

 

[CZLN6]

Howdy Again EB:

Be sure to establish the cylinder bore line on to the head surface. Do not relieve the combustion chambers beyond that point. adding relief around the valve reliefs does help, especially if you're adding bigger valves. Smoothing the chamber surfaces has two goals; removing potential hot spots and reflecting heat. With these heads on this small bore engine, smoothing looks nice, but is a marginal gain, so don't get carried away. The greatest gain in porting these heads is the area within 2" of the valve seats. Blending the transition between as cast and machined in the intake port just under the valve seat is the area of greatest gain. Also reducing the width of the valve guide bosses.

I have a collection of burrs, stones, an abrasive rolls from anywhere I could find them. Check Sears, Harbor Freight Tool Co. and any nearby hardware store.

Good luck and keep us posted on your progress.

Adios, David

 

[rbohm]

Howdy Again EB:

Be sure to establish the cylinder bore line on to the head surface. Do not relieve the combustion chambers beyond that point. adding relief around the valve reliefs does help, especially if you're adding bigger valves. Smoothing the chamber surfaces has two goals; removing potential hot spots and reflecting heat. With these heads on this small bore engine, smoothing looks nice, but is a marginal gain, so don't get carried away. The greatest gain in porting these heads is the area within 2" of the valve seats. Blending the transition between as cast and machined in the intake port just under the valve seat is the area of greatest gain. Also reducing the width of the valve guide bosses.

I have a collection of burrs, stones, an abrasive rolls from anywhere I could find them. Check Sears, Harbor Freight Tool Co. and any nearby hardware store.

Good luck and keep us posted on your progress.

Adios, David

cant add anything to this.

 

[JackFish]

Here's a nice exhaust port, if you haven't yet had enough...:

 

[edgewood bronco]

Thanks, David. It sounds like I'm in pretty good shape then. When you refer to the 2 inches from the valve seat, I assume you are referring to the passage side, not the combustion chamber side (I guess the combustion side is not technically porting...is it?)? Just want to be sure.
Good point about the head gasket line. I'll scribe a line so I don't booger anything.
Thanks, JackFish for the foto. Something to aspire to!
By the way, this is out of a ca. 78 Granada, so It has big valves, and I'm not putting in anything oversized.
Best,
Andy

 

[xctasy]

Mustang Six had a "Log is a Dog" engine analyzer post some time back, and he follows through the common logic the Schjeldahl Brothers do, and that is exactly right on what everyone should do, focus on the 2 inches from the valve with long hours of die grinder work. It gives you the biggest improvement. Don't over port the exhaust area, David is right, just port mismatch with the outlet of the head smaller than the exhaust

I'm with all that, but when I did some trail a semi Independent runner, partly Port on Port system of carbs, such as the dyno runs we did back with Bill in Indy (now named pssnmn1) , we also found that the primary goal for a 25% performance boost is to limit the total amount of 90 degree bends the air /fuel mix has to turn. For every dollar spent, that gives the best benefit. What doesn't' work as well, but does give a uniform 15% or so, is the truly horrible early Offy or Edlebrock alloy bolt on log tri-power with 1.09/1.3/1.09" front to back holes small log with triple 34mm ICT/ICH's, small or large 1904, 1908''s or 1100/1101's. Better by far is the big log with 1.4375/1.6875/1.4375" front to back holes, and the same carbs, but its still down on a fully hogged out log.

If you open up the log to three 1.75" holes, you have full access to smooth-en the entry to the intake ports, and there are plenty of tripple 300 Carter 1.6875 throttle, 1.4375" venturi YF's which bolt right on. You are then able to open up the intake ports, and have the best manifold and intake ports.

Ford guys here have paved the way to fix the problems with matching turbos and great carburation to I6's.

The idea first came from Lincs 200 over the prospect of better induction.

see Multiple TBI's (revisiting)

old link was viewtopic.php?f=51&t=26454&start=0



First big break was the awesome triple 1.75" hole adapter, the best one from one from our member here rwbrooks50.

The offy is too tall and too small in porting to work well, so your better off making a low deck welded intake like on rwbrooks50's website

http://s529.photobucket.com/albums/dd33 ... 0Ranchero/





None of that namby, pamby, la-de-da small a$$ 1.09 or 1.4375" inch outer carb hole crap the Offenhauser and Edelbrock bolt on log adapters force us to stomach...

The Argentinians have been doing it for years...

A stockish engine, and a lot of good networking from all of us will make this thing work, I'm certain.

You can access the log pretty easily by drilling it, see viewtopic.php?t=37661


And cutting the top off, see viewtopic.php?t=54715

And it has been Dennis Schjeldahl who has lead the path which myself and Falconaround have followed:-

......This was a project head (now very rusty) that I milled the top off the log. The original intent was to be able to bolt on a steel plate that would run a pair of Holley/Webers, or with a different plate, running all sorts of combinations. BUT - - STUFF happens, and... well you know......


http://falconperformance.sundog.net/pic ... hing-3.jpg

........Dennis

The typical 300 six set up of YFA Carters is very easy to swap into a small I6. Colton Anderson's youtube 79 F150 is a typically early American example of what can be done on a budget.



After bolting a plate back on it, you can then make the would head a lot more efficient.
606 cfm of carburation was never, ever easier than three 1.4375" venturi, 1.6875" stock emissions era Carters.
http://s1215.photobucket.com/user/xecut ... t=3&o=1064