I own a 305 1985 z28 engine. I most important performance enhancement is to port the heads or spend most of your money on the heads. WHY? BECAUSE EVERYTHING (EVERYTHING!!!) Goes through the heads. Is there a website? Could someone make a tutorial with pics etc. Thanks.

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1984 Firebird SE
1985 Camaro z28 305 engine T-5 Five Speed Tranny, 92 Camaro Leather Seats Console, carpet everything. Soon to put in 700R4 and 427CI. (Hopefully.
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It is also for sale, please make me an offer. Thanks.

 

Do a web search for standard abrasives, they have a kit and online tutorial, complete with pic's.

 

'84,

I've done a head or two. Heads are where the power is made, no doubt. Good heads can even compensate for an "average" cam profile. (I'd rather have good heads any day).

A pictorial guide would be difficult, since three-dimensional photographs are not yet a reality. I do have a few of the old-fashioned two-dimensional variety, however. They might give you a few ideas.

The bowl area behind the valves is very important. Not only can the valve bowls have a restrictive diameter compared to the valve face, but the valve guide intrusion into the bowl can add to the restriction:




The bowls need to be opened and the guides tapered and cut back squarely so that they still provide support but with minimal intrusion:



The valves themselves can be restrictive to flow, and even though multi-angle seat grinding is very popular, radiused valve faces can actually add to the flow rates better, expecially on the intake side. Doing both might even be better. The third from left has a radiused face:



Of course, the port runners themselves need to be able to support good flow to and from the valves. The design should support adequate flow volume while still maintaining flow velocity for lower-end RPM cylinder charging (for better torque). The small cross section factory ports with sharp angles can't help the flow through the head. It's best if you can open them to provide the straightest flow to and away from the valves, while maintaining adequate casting thickness of 0.220" minimums on iron heads. The idea is to be able to see as much of th evalves from the ports as possible, with as little taper or restriction as possible:



This usually involves raising the port ceilings as much as possible and matching the intake manifold ports to the system:



If you get the port and valve sizes correct, an otherwise "marginal" cam profile can provide improved flow while not sacrificing torque and fuel economy. Extra lift and overlap aren't always the final answer. A lot of racers are restricted to low lift numbers in their classes, and still manage to make plenty of power. It's all in the heads.

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Later,
Vader
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If you want to beat the World, it might reach up and pull you down...
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I used a sand paper flapper roll bit for a die grinder on the exhaust ports to polish them up into a mirror finish. I have aluminum heads, and the casting was quite smooth to begin with, so it didn't take much time/effort to mirror finish them.

Doing this also allowed me to gasket match the exhaust ports carefully and efficiently.

 

Search my posts for a discription of how I
*home ported* my 305 heads. There are flow figures too. Turned out pretty good for a budget street head.

 

Their website is http://www.sa-motorsports.com/

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
317 RWHP, 418 RWTQ
13.23 @ 107.62 MPH (2.10 60')
Southern California
Member: SoCal 3rd Gen F-Bodies
Member: SoCal F-Bodies
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