4A-GE head work

[NoHachi]

Hi,

A port and polish is a very knowledge intensive operation. I suggest you don't attempt it yourself. Only let a machine shop perform this and only let them do it if they have tons of experience with motorsport engine preparation. A bad port and polish can cause more harm then good.

To be honest, the gains you'll see with just the headwork are minimal. The std ports really flow enough for the stock cams. Make them any bigger and you'll lose a lot of low RPM torque and gain not so much high rpm horsepower. On a bluetop engine the gains are even smaller as the ports are massively oversized for the engine.

Of course years of wear and tear do take their toll on the engine, so there are still some things you can do with a dremel and a little patience: Clean the entire head of carbon deposits; these form hotspots in the combustion space and cause knock. Take a look at the ports, remove any casting ridges etc. Finish the entire port with some sanding paper until it has a satin gloss. DON'T polish the ports! The extra turbulence from the satin finish prevents the builup of a boundary layer against the surface of the port. This helps with fuel atomization, flow and reduces the amount of wallwetting you'll get.
The next thing you want to do is port match the intake and exhaust. Take a new gasket and a dremel, start grinding away untill the intake and intakeport exactly match the gasket. All the transitions between head and manifold should be smooth and ridge-free.

Clean out your manifolds! Carbon can build up enormously in the exhaust header. Its the cause of 50% of the effect people notice when changing over to a new clean tubular header. The original toyota design is outstanding.

That should keep you busy for a while :wink: