ANY IDEAS??? Head Question.

[Paddles]

Below are some pictures i took of a head from a GH scorpion i just recently wrecked, original motor from what i can tell. it has 4 extra little valves on the intake side. any ideas what they for or what they do??? it looks like a 12 valve astron head. very unheard off.

[C_Fernance]

Thats a jet valve head. They were supposed to help lower emissions.

I'd replace it with a standard head - they are prone to cracking very easily.

[shuggy]

thats nuts!

[75wagon]

I used to have a 4G32B head like this. It was an import motor. I got the extra valves welded up, the extra arms had already been cut off so they didn't work anyway. They weren't seating properly.

[Paddles]

hey. have no use for it as yet. just pulled the rocker cover off to have a look and got a shock. besides lower emissions would it be any benefit on performance??? anyone else know much about these heads as in which cars or years they were around??

[stealth]

the jet vavle head is of the conquest turbo engines or any late us engine
thay affect performance dramaticly in a bad way
take all the parts of it and bin it!
cheers stealth

[Paddles]

so its no good really then?? or you mean remove all jet valves etc and use as a standard head?? does that mean this motor could have been a conquest motor?? it just looks like a 4g52??? it has high top pistons and no markings on block except for engine number on tab above oil pressure switch. normally 4g52 or 4g54 is cast into the block where the starter motor sits but nothing there.

[stealth]

what im mean there useless
no good at all
take all the studs and bits and pieces that you could use on a normal head and throw the rest
away
and yeah thay did come factory on a 4g52 astron 80
i use these heads as a jig for welding turbo manifolds up thats all its good for!
sorry mate
cheers stealth

[13bsigma]

sell it on ebay hahaha.

"exteamely rare 3 valve astron head to suit sigma or scorpion $1000" hahahahaha

[colta51]

this is a M.C.A. jet head (mitsubishi clean air) its to do with emishon control
dont think its any better than a normal one tho? look it up on google

[Draff]

Could be from a Astron 80 motor, best you can hope for it becomes a collectors item one day

[Paddles]

ill keep it in the shed, just so i can say i have a 12 valve astron head. lol, it came of a 2.0 litre. still have the rest of the motor.

[Sigmaproject]

It was just one of the ways that Car Manufacturers got around the emission laws in the 80's

It's all about burning any fuel that may have escaped being burnt during ignition

After ignition, and as the piston is on the way back down , the exhaust valve open's, then the jet valve opens to add oxygen to the exhaust gas to give a more complete burn of the exhaust gas before it goes out the exhaust and into the atmosphere.

The unleaded Sigma and Carby Magna's have a reed valve setup , that does the same thing.

Before that it was the infamous air pump that pumped air into the exhaust gas to do the same thing.