port/polish 3.4 heads??

[govno88]

hey guys.
has anyone done a port and polish on their 3.4 camaro/firebird heads? and if anyone has, how much did you do and what were the benefits? i'm sure that if i dug deep enough into the many pages of information on this site i'd find my answers, but there might be some updated advice from articles that are a year old.
i'm doing a 2.8 to 3.4 swap. - 4.3 tbi. - mild low end cam.
what can you offer me.
thanks

[ForcedFirebird]

Welcome to the site!

There's many of us who have ported them, are you looking to do them yourself?

[govno88]

thanks for the welcome
yes, i'm going to try to do it myself. i've gone onto other websites that explain the process of porting/polishing, and most say the same thing. long process, take your time. my thing that i would like to know from the 3.4L guys is, how far do i take it? do i remove that large hump in the middle of the intake port or is it there for a purpose (swirl)? do i do a complete intake to head to exhaust manifold port match, or would it be good enough to just get rid of the hard edges and the castingprints.
not to knock these engines, but i've read that these weren't the best designed heads that GM has put out. i do remember seeing a few articles about doing a 3.8 head swap, but that<s much more than i want to get into.
again, thanks for any input

[geoffinbc]

I did the full treatment to my heads I put on my Trooper. Start by gasket matching the intake ports of the heads. There is a lot of material that can safely be removed in this area. Then (with the valves removed) blend the machining lines under the valve seat to the valve bowl. Then profile the valve guide. Once your done the initial work just blend in the work that you did on the intake ports into the valve bowls. DO NOT remove the vane in the floor it helps increase port velocity. Just profile it smooth. Also don't start hogging out excess material it will ruin the ports.

On the exhaust side do the same bowl blend under the valve seats. But do not open the exhaust port to the size of the gasket. Again just smooth this area out.

There is nothing wrong with the design of the head. It was simply a smog era head and was not optimized for performance. But its no worse than any other iron head of the era. And a Buick 3.8L heads swap is not possible on the 60* block.

[ssdurango]

Beterthenyou>>> Why not open up the exhaust ports to the gasket size?

Thanks,
Tom

[pocket-rocket]

Reversion and loss of velocity.

[ForcedFirebird]

You need the heads to flow a specific amount exhaust to intake ratio, that's why. Just polish the exhaust ports to help reduce carbon build-up, leave the shape for a flow bench. Remove casting marks and blend the intakes to the gaskets.

[pocket-rocket]

And John bursts my bubble. And here I thought I had a sound answer Thanks John... lol

[geoffinbc]

Yup you want the step between the exhaust port and the manifold. That is why on all headers you will find the size is much larger that the size of the exhaust port. The step helps the scavaging effect of the exhaust system