Polishing Heads Info Needed

[MC75Z]

This is the first time I have polished a head. Would be interested in any general information on procedures. Was told by one person that it is better not to polish to a high sheen but to leave a slight roughness to it to help the gas & air mix.

Also would like to know the value of the water circulation through the intake manifold. Was told by someone that the only reason it was there was for the emission control system. The car now is smog exempt so could it be bypassed or is it still needed?

Contact me at: terimdc@yahoo.com

Michael Cornish

El Cajon, Calif.

1973 240 Z Series 4 Coupe

1974 260 Z Coupe

1975 280 Z Coupe

"Drive Fast- Take Chances"

[e_racer1999]

polish the combustion chambers and the exhaust ports, but leave the intake ports a bit rough.

port first, then polish, initially (if porting and not just polishing) use the smoothing head (the one that looks like a turbine).

otherwise, a polishing head (the one that looks like strips of sandpaper) works wonders.

[MC75Z]

Thanx for the reply. Now do you know anything about the 2nd part of my post?

The part about the intakes?

[=Enigma=]

To answer your intake/water question, I believe this was done to improve fuel atomization at colder temperatures and to regulate the temperature at the carbs during hot weather and long periods of low speed driving where the heat from the exhaust manifold can become detrimental to performance. There is probably some emission related value to doing both, but you probably won't need either in your neck of the woods, unless you get caught in LA traffic on a 100+ day. Mine was plugged when the PO switched to the older SUs from the flat tops.