Quote:
Originally Posted by hfmt93
Very good writeup!
This is very good info, but it is easy to get carried away with all this. 4v6 is serious when he says it takes patience. It takes a lot more time than anticipated. I really do not even see how you got into the bowl so good. Can you show a pic of all the tools? Especially the one used for the bowl area.
I messed up by trying to contour the casting marks in the side of the tunnel. You get carried away and ready to be finished and stop thinking. I have now found a new set of heads and will probably be leaving them stock. For now. This pic shows the casting marks I messed up on. Use caution:
Mr2good makes a good point. From looking at all the data 4v6 has come up with I believe these will make power, but the only real way to tell is drag times and dyno in my opinion.
One thing I noticed when messing up mine is the valve seat insert's machining made the insert a "step" into the airflow. Did you see this on any of you heads? Did you mess with it?
4v6 this is amazing work and data. Beautiful curves on the finished ports. I always enjoy reading your threads like this. Please, keep up the good work and thanks!
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Hiya, thanks for your feedback.
Yeah the access issue can be a hard one for someone doing this at home, but most of the tools are fairly simple.
A quick description of what i use.
Oval carbide burr- thats the item shown removing material from the port.
Thats the most useful shape ive come across so far because it tends to blend surfaces quite easily.
Important not to press on it tho, just let it cut.
I run it at around 7krpm ( slowest speed on my grinder) because it becomes a problem with clogging at higher speeds and less controllable.
I also use sanding rolls from standard abrasives- they do a small kit which has lasted through at least 10 heads so far and still going.
One of the most useful items is a split fork deburrer.
Its just a length of 5 or 6mm thick rod, with a slot in the end- i have two, one has a flat end the other is shaped like an artillery shell.
You just tear off a strip of emery, fold it and slot it in equally then use it like a sanding roll.
Its a vital piece of tooling for finishing as its extremely gentle even in 80 grit emery yet it can still remove material and further blend hard to access areas of the port.
Ill take some photos later of what im using to better illustrate them.
These 3vzfe heads do have lots of steps and dimensional changes that have an effect on the airflows, but ill tell you this; theyre very easily made to flow.
Most people can do them, but where it gets tricky for the homeporter is knowing whether or not theyre balanced and all flowing the same.
Ive found its very easy to get large discrepancies in flow if youre not consistent in how you approach these, its very likely the same with others too.
I think ive probably modified most all aspects of these ports by now, from making them bigger, smaller, wider, higher, changing the angles the air flows in, waisting the valve stems, changing the chamber shapes and on and on....
Thats not to say i know every aspect of whats possible with these cos i dont think im even close yet but its nice to have actual data to refer back to.
One area i do want to focus on before too long is valve and valve seat geometrys.
Its far from clear how well these are doing as regards flow and i feel certain there are some nice gains to be had in that area alone.
One thing the 3vzfe intake valves do have that makes them flow quite well is a 30 degree back cut on the reverse side. so Mr T's engineers have obviously done some work here.