.

We can start with any standard head, it doesnt need to be a GT casting, a standard one is fine, in some instances better, even low compression casting can be used, (they're the same but thicker!) it depends what your trying to achieve. The important thing is to find a good casting without cracks and minimal corrosion, and thats becoming increasingly difficult.

after we've cleaned the head, we'll check for casting damage then start working with a die grinder to open up the ports, valve throats and chambers.

Once the ports are nearly there we get the seats cut for the new valves, and this will then allow us to open the port out more accurately round the throat and to match the valve seat at the optimum size.

Once the seat are cut and blended we'll use a dummy valve to protect it and make a start on the combustion chamber, this is the tricky bit, you can only unshroud the valves so far out because of the bore of the cylinder and head gasket, equally, the more you remove, the lower the compression ratio, we can get some of this back by skimming the head later but there is a limit. Once the chambers are complete we will recheck the valve seats, finish the porting and check our work on a flow bench, what we're looking for is a good smooth curve showing air flow in, and out of the chamber right from the moment the valve lifts off the seat and smoothly increasing all the way up to maximum valve lift, again this is all variable depending on engine capacity and valve size, and the kind of result your looking for. But simple theory says the sooner the port starts to flow the better, in reality valves are only part open most of the time so good low lift flow is of paramount importance.

One piece narrow stem plasma nitrided valves we stock several different types of valves, from standard to Full race on piece narrow stem for FJ/MAE and 1500-1650 precrossflow, we also stock lightweight steel ratainers and collets and full race spring sets

 

Heads are finally skimmed to acheive the required compression ratio, we will fit bronze as they are a must with anything but standard valves, iron guides are not suitable even if they are cheap, and the heads are all old and worn, and hardened unleaded seats for general road use with unleaded fuels.

Depending on final useage we will also machine and or shim the valve spring seats to correct the installed length of the springs (If your using uprated and or double springs for example)

Finally we'll degrease, clean and assemble, oh, and a lick of paint doesnt go a miss !

We have seen many heads prepared by other companies which look like works of art, but by and large they are exactly that, works of art! If anything a mirror polish can be detrimental to a homogenised flow of fuel/air mix, people do argue that it helps stop build up of carbon deposits, but again this is negligible, getting an engine set up properly will be far more beneficial. The one thing that doesn't lie is the flow bench, its callibrated every use, and more often that not we've had struggling race engines turn up with heads which flow little better than our road heads fitted with the original Ford valves.

Please feel free to contact us for any head or valve requirements road or race, we do keep all parts in stock, but complete competition heads, like a good suit are tailor made.

 

If you would like more information about any of our products please email us : joe at throbnozzle - racing.co.uk

Thanks.