Georgia Fiero Club Forum

All Things Fiero => Tech Tips, Tech Questions => Topic started by: f85gtron on May 07, 2016, 08:46:05 am

Title: Ported iron heads
Post by: f85gtron on May 07, 2016, 08:46:05 am: Anybody got pics of ported iron heads? I've begun porting mine and would like to compare and make sure I'm heading in the right direction.
1) removed the spark plug hump
2) gasket matched the intake side
3) shark finned the intake fin
4) shaped the valve bowls and valve guide protrusions

Did i miss anything?
Title: Re: Ported iron heads
Post by: Roger on May 07, 2016, 11:48:58 am: Gasket match and polish the exhaust ports. Grind down any casting 'flash' on the water jackets. The flash ONLY!

Shark finned the intake fin? That's a new one on me.
Title: Re: Ported iron heads
Post by: f85gtron on May 07, 2016, 12:46:52 pm: I'm a little confused on the exhaust ports. I was thinking the same thing about gasket matching them, but the camarobird guy's discussions conclude on leaving a little bit of rim because it supposedly promotes scavenging. I'm on the fence. Watcha think?
Title: Re: Ported iron heads
Post by: Raydar on May 07, 2016, 11:09:56 pm: I have heard the same thing as well, about the exhaust ports. Leaving a bit of a lip, where the header bolts on, will (allegedly) prevent the gases from back-flowing. (Allegedly.)
I've seen them leave a small lip, and even an additional "raised, flat floor", in the exhaust port. Kind of looks like a "D", sitting on its face.

Here's some pics of my port work. (Done by Goza, in Woodstock.) Unfortunately, none of the exhaust ports.

(Ignore the red circle.)

And the intake. Ported by Darrell Morse. (No longer doing this, as far as I know.)
Title: Re: Ported iron heads
Post by: Roger on May 08, 2016, 09:22:47 am: You are correct. A little mismatch between the port exit and exhaust (header) is desireable to keep the exhaust pulses from rushing back into the port. I only meant to clean out the casting flash. Sorry for the confusion.
Title: Re: Ported iron heads
Post by: f85gtron on May 08, 2016, 10:20:56 am: Those have got to be the best ever shark fin port jobs I've ever seen. Very uniform and look like they where cast that way. I've poured over thousands of photos to get ideas and those are the best I've seen. Wow. I'd post mine, but I'm embarrassed after seeing those......
Title: Re: Ported iron heads
Post by: f85gtron on May 08, 2016, 10:23:34 am: Quote from: Roger on May 08, 2016, 09:22:47 am
You are correct. A little mismatch between the port exit and exhaust (header) is desireable to keep the exhaust pulses from rushing back into the port. I only meant to clean out the casting flash. Sorry for the confusion.

No harm :) I'm just confused because the idea of leaving some lip is counter-intuitive to the discussion as a whole.
Btw, how much lip?
Title: Re: Ported iron heads
Post by: TopNotch on May 08, 2016, 04:08:27 pm: Speaking of leaving a "lip" on exhaust ports -- later model duke heads had D-shaped exhaust ports, and they made more HP than earlier ones with round ports. I have one of the later heads on my modified duke in my yellow car. In this picture, the original head (which turned out to be cracked and had to be replaced anyway) is at the top, and the replacement head is at the bottom.
The same round-port manifold fits both heads.
Title: Re: Ported iron heads
Post by: Roger on May 08, 2016, 06:40:34 pm: Just take the port to the point where you can pull your finger across it and not feel the casting edge. I knnow what you mean about confusing though. I port matched my 350 to the gasket and although I didn't put the engine on a dyno before and after the seat of my pants told me I hadn't done any wrong. A touch more torque. But all of the HP articles you read say to leave a lip. My deed was done way back in the 1900's. Hello Internet! BTW, the smoother you can make the inside of the exhaust port the better. Then there are articles about making them 'swirl' inside. A whole 'nuther story I guess. :o
Title: Re: Ported iron heads
Post by: Roger on May 08, 2016, 06:44:22 pm: Odd that the D ports made more HP than the round ones. Pontiac had the round port RAIV heads that made gobs of power. I wonder if it's the shape of the chamber or that ever present 'hump' on the intake port? Sounds like an investigation is in order.
Title: Re: Ported iron heads
Post by: Raydar on May 08, 2016, 08:32:34 pm: Quote from: TopNotch on May 08, 2016, 04:08:27 pm
Speaking of leaving a "lip" on exhaust ports -- later model duke heads had D-shaped exhaust ports, and they made more HP than earlier ones with round ports. I have one of the later heads on my modified duke in my yellow car. In this picture, the original head (which turned out to be cracked and had to be replaced anyway) is at the top, and the replacement head is at the bottom.
The same round-port manifold fits both heads.

Maybe that's where I got the "flat floor" thing from. Perhaps that wouldn't be useful on the V6.
Regardless, I seem to remember the "lip" around the exhaust port being just a bit smaller than the steel O-ring in the gasket.
Maybe 1/16". Certainly less than 1/8". I seem to remember seeing some pics, but I couldn't tell you where.

As for my "shark fins", and port work... Goza (or maybe it's Gosa) has been doing this stuff, for years. Chuck Willyard recommended him to me. It's something I wouldn't have even attempted.
I have his card downstairs.
Title: Re: Ported iron heads
Post by: Sarge on May 12, 2016, 04:14:44 pm: will you also be doing a valve job? if so a multi angle cut to the seats helps Considerably along with bronze seats to help dissipates the heat and the bronze is gentle on the valves. also the valve guides can be tightened up with bronze guides.
Title: Re: Ported iron heads
Post by: GTRS Fiero on July 28, 2018, 09:57:49 pm: Sarge, does your Fiero have the multi-angle valve job?
Title: Re: Ported iron heads
Post by: GTRS Fiero on July 28, 2018, 09:59:06 pm: Quote from: Raydar on May 07, 2016, 11:09:56 pm
And the intake. Ported by Darrell Morse. (No longer doing this, as far as I know.)

Does porting the intake here do much? I thought the porting was in the plenum.