The V8 Owners Forum -

Just a quickie!!

I'm tinkering with porting now that I have purchaed my first carbide burr. This is a real good tool eh? Much better than stones and flap wheels...

I'm using a 250 watt flexi drive Dremmel that seems to work ok if I'm gentle.
I have found the burrs seems to like a lower speed and a bit of pressure to shave the ally off. It may not be ideal but I can get along with this setup for the time being.

I'm only doing the exhaust ports by the way as its for Nitrous use.

My question is!!!

Does anyone have any info or pictures on where the waterways in a Rover V8 head are in relation to the exhaust ports??

I've got no problem with the amount of metal I have removed from the runner wher I have opened it out to match the exhaust manifold flange. But how much can I take off in the chamber above the valve??

Perry

There is a picture of a sliced open head on this website:-

http://www.g33.co.uk/tuning.htm


David Hardcastle's book has the same pics!

Perfect!!

Thanks Sidecar...

Perry,

There is quite an advantage to be had by increasing the Ex. valve size to 1.4" which can be done by recutting the existing seats, this is particularly relevent to Nitrous use.

The area below the seat should be opened up and blended into the bowl.

The area around the valve guide can be smoothed and the port runners can be opened to gasket size and polished. Further improvement can be had by raising the roof of the ex. port and creating a smoother radius but there is limited metal to work with here and there is a danger of breaking into the thread area for the manifold bolts. at the side of the port.

There are some good actual size plans in the Hamill book but i do not have a scanner so cant send or post them on the forum.

If you don't have the book I would recommend getting it, it really is essential reading.

It is worth doing the inlets as well, you can fit the 1.63" inlet valve by again recutting the seat then grinding the insert out to the seat size and then blending the bowl to match.

These simple mods are worth at least 35BHP on a 4.6 engine. If you know a firm with Serdi valve seat cutting equipment they can cut the seats and do a 3 angle job at the same time.

Kevin.

Thats interesting Kevin. I thought you had to have all the seats replaced to fit bigger valves, so that makes life easier.
I'm practicing on scrap heads at the mo while looking for another set of EFI heads to actually do.
You are right about nitrous. Thats why I'm only doing the exhaust ports.
I'll have a chat with some folk I know to see if I can get the bigger ex valves cut in.

Perry,

I could photocopy the full size drawings from Hamills book and post them to you if you like then you will have them to actual size.

It's surprising how restrictive the standard heads are just behind the valves, especially the exhausts. If you do both inlete and exhausts it will be the cheapest 35BHP you can buy and thats not including the effect of the nitrous.

Strangely I was only thinking a few days ago that you should do this are you telepathic!

Kevin.

Cheers Kev!

you can mail the stuff to me at

perrystephenson7@hotmail.com

I've been thinking about opening the EX side up for nitrous use for over a year. But I have only just got around to attempting it and having a practice.

Thanks
Perry

Perry,

I'll have to snail mail it to you as I don't have a scanner but at least they will difinitely be to scale, just send me PM with your address and I'll pop them in the post.

Kevin.

Done
Thanks Kevin

Also some pics on our own forum....:

http://www.v8forum.co.uk/forum/viewtopic.php?t=4016

I'm doing my heads at the moment, and on those bits of head in the photos, I drilled through the port side into the water jacket to see how much material there was. There was plenty around the valve guide area.

Chris.

Thanks Chris.
This is a bit addictive isnt it?
I've got 6 spare heads to play with so I can practice for ages.

Perry.

Did you get those drawings I sent?

Kevin.

Kev!
The drawings are now cut to A4 and laminated ready for use. They are spot on mate. Thanks very much.

I've emailed JE about a cost to have bigger EX valves fitted to some heads for this bit of R&D. Was it you that said I can get bigger valves in by cutting the existing seats??

I just found another pair of heads so i have 8 to practice on now

See you soon
Perry

Perry

The biggest Ex. valves you can fit to the standards seats after a recut are 1.4" Inlets 1.63". which are the standard upgrade to big valve heads.. the next size up Ultra big valves require new seat inserts.

Any auto engineering firm with valve seat cutting equipment should be able to do it for you.

Kevin

Kevin, can you cut the valve seats to suit the 1.4" valves with hand seat cutting equipment or does it need to be popped in a mill or something?

TC