Redoing grey head

[newman]

I will be redoing another head for my mild grey motor, am thinking red motor valves,inserts for unleaded,double valve springs, port and polish and a shave for good measure. My question is how much is safe to shave off I did get offered a few heads when I was looking for a replacement head to work on that had been shaved so far down the tell tale thumb print in the middle of the head surface was gone.
I've heard of stock car racers taking too much off and having to elongate the sparkplug holes in the sideplate to get the plugs in although I'm not sure if its just another "urban myth"

I'd appreciate comparing any information from those that have been down this path as to what is the best mods to do.

Mick

[weddo]

How mild is the grey Mick ?

If it is only twin carbs, headers, and a little cam, you will only need to make it breath efficiently. Red motor valves are a start, or late model commodore with turned down stems, 308 valve springs, 20 thou max off the head and port matched to your manifolds elongated internal ports - not circular, roughened inlet and smooth exhaust, and hardenend seats.  The more you do to the top end, the more you will need to do to the bottom end.

Good luck and seek out someone who is knowledgeable in machining early heads to do your work.

regards

Weddo

[newman]

Weddo its running twin strombergs,extractors,30/70 cam and electronic ignition, I just want to improve the breathing more. Can I use 308 valve springs  if I go with red motor valves, and aren't red motor valves the same size 149 up to 186?? I'll go 10thou of the head just to clean it up.

I know its cheaper and better value to put a red in but I like dinasour motors

Mick

[colt]

Mick, nothing wrong with dinosaur motors. You are restricted in valve size by the chamber size. If you want to go bigger still you have to modify the chambers as well. Red motor valves with the breathing mods Weddo suggested would be a worthwhile start. If you start going too big you'll find you have to start thinking about the bottom end more. A bigger chamber may also mean custom made head gaskets. How much do you want to spend.

Colin.

[newman]

Colin,

Just trying to make the grey breathe and run a bit better, my days of going fast are (almost) over seriously though do you know of a machine shop in Canberra that are experienced with greys that could do the machining work on the head?

 Weddo you suggested 308 valve springs, are you talking about early red block 308's or are they the same as the later 308's?

Mick (Living in the past)

[colt]

Mick, see Warren at Fyshwick Head Services. He's in a workshop behind the Ford Wreckers in Maryborough Street. He does all our machining for us.

Colin.

[newman]

Thanks Col,

I just googled them up and got the number (02 62800480) I'll strip and cracktest my spare heads to find a good candidate as far as I know the chamber size is the same on all greys 132 / 138 ?

Mick