and the proof of that is........

Theres definately also a slight touch with the CNC to the inlet sides where they meet the manifold to do a port match.
Was clearly visible on all ports of the 220kw engine i just put into the missus AU Ghia.

the black paint, and the cnc milling

cnc milling in these places guarantees a y/t gt40p

 

 

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gt40yt.jpg [ 67.03 KiB | Viewed 421 times ]

Just had another check and there is no number stamped in there.

No one has any more info on the 200kw head?

It would be good if we had photos and details of the standard GT40P heads the 200kw and 220kw heads as a sticky so everyone can tell them apart.

pretty sure 200 heads are just std gt40p's

Correct.

200kw had 1.6 crane roller rockers
220kw had yella terra 1.7 roller rockers
thats what i have seen back when the v8brutes ran windsors
if that helps

I thought it might be a good idea to document what modifications Tickford has done to the 220kW heads. So now that I have a nice clean set in my workshop I will describe what I can see has been changed from a standard GT40P casting which I also have right along side. These modifications are what this set has. The heads came off an AU2 engine. Number 4 rod did not match the others (no SPS bolts, just the standard ones) so the engine may have been apart previously, or it may have been incorrectly assembled at Tickford.

Intake ports have a slight machining on the sides of the port. It is so slight that not all ports were touched on both sides. The machining goes a maximum of about 15mm into the port, some are much less and some are untouched. There is a ridge between some machined and un-machined surfaces.

Intake bowls have been plunge cut (throated out) to accomodate the larger intake valves. The transition from the fresh cut to the original bowls is generally quite nice without excessive ridges or sharp angles. Unfortunately the short side radius lets the intake work down. It is much sharper than a standard casting due to the larger valve and bowl diameter.

The intake and exhaust valves are Ferrea single piece stainless with a Yella Terra part number. They have undercut stems and judging by the part number, are from the Ferrea 5000 series of street performance valves.

The valve springs are single with a flat wound damper. They felt stiffer than factory springs when I was removing them. Standard retainers are used, and the springs are a very poor fit into them. If my machinist presented me with work like that I would find a new machinist. There is 4mm (or more) of slop in the exhaust retainers and a little less on the intake retainers. No wonder they break valve springs. Harmonics and spring walk are also likely to be a problem.

The combustion chambers have been machined (approximately) down to the level of the valve seat top cut in the area between the valve seats. A radius cut has been made on the chamber walls surrounding the valves to reduce shrouding. This is a really nice touch and does improve performance.

The valve seats have a 2 angle job on both intake and exhaust.

The valve guides were very worn, and the backside of the valves caked in burnt oil deposits. The engine only had 125k's on it. A standard GT40P valve guide is generally good to double this distance. I assume the stainless valve stems have been a little harder on the valve guides than the factory GT40P valves. A set of K-line guide inserts brought them right.

The exhaust bowls have been plunge cut (throated out) to accomodate the larger (1.55") exhaust valves and exhaust valve seats have been fitted. I'm assuming these are hardened. Again the transition from the fresh cut to the original bowls is generally quite nice without excessive ridges or sharp angles. Short side radius is OK, but not as good as an untouched GT40P casting.

The exhaust ports have been machined on the roof and half of one side going into the port about 10mm. The machining is OK but there is a definite ridge and trench where the cutter started on every port.

And of course they have factory fitted Yella Terra 1.7 ratio roller rockers.

How do I rate them? Quite good for a factory enhanced engine, but not quite so highly as they were sold as being a hand-built engine. If those hands grabbed a die grinder for 45 minutes and finished the job (short side radius and final blend of machined port and bowl surfaces) they would be so much better. And if they had spent just a little extra cash for some decent retainers I would have described them as excellent.

I will check the next 220kW heads I do to see if all these mods are present in them, although that won't be for some as I've got a few others to build first.

Im ion the same boat have the yella terras in 1,7 im guessing yet i have a au111 xr8 ute and little oil cooler and tickford snorkle but 65ml tb. So curious also but i guess once the cam is out on sunday will now what engine it is