That's the book.
Let me first start by admitting that my cam is too big for my application.
I'm ok with that.
I've blown the head gasket and here I am with the head in my garage. I'm going to pull out the valves and clean everything up. It's not an issue to take 4 vavles to work and cut some grooves. I feel like experimenting. I'm glad no one's responded with "if you do that your car will blow up".
That book, though, is great. Although it's only about the British A series, it goes into alot of detail that can be applied to other types of engines. I bought it for the information on SU's.
Also, this book is a bit heavy as far as bathroom reading materials go.
No, no rally car safari lights. I've been able to get it to idle at around 1200rpm but if the radiator fan kicks on, at night, at a red light, the engine starts slowing down and eventually dies.

i think hes talking about a rally that that has massive amperage spotlights on the front, and if it is a rally car it probly has alot of other things running at same time......

Thanks guy, I'll have to check it out. I've heard of Vizard, if I remember right he consulted on lots of Formula 1 engines.

Cable_Tie, you mean 1800 rpm idle for a street-driven car? The 8000-rpm A15 I rode in idled probably around 1000 rpm. I could see it for a race car ...

Sorry DD
But i'm pretty sure he is talking about the BMC A series, like the ones in mini's.
I have the book and its a useful book for engine building in general.
David vizard has written quite a few different books but i believe they are all for british engines (he's british)

Nick

Im not really sure if they would work.

I've seen pro stock and top fuel heads and they dont run these type of valves so im not sure what to think.

Never seen this type of valve before.

With the old engine, we had problems with carbon buildup on the back of the valve.

This was one of the reasons for the "rimflow valves" or as we have always called them: "Valves with anti-reversion rings".

We did not have the carbon build up with the new engine. Cam timing was altered at the same time which can also have an impact on carbon buildup.

Come on DD, not everyone has an engine with a heavy flywheel and small primary to give a nice idle. . .

Quote:There's a book dedicated to the Nissan A-series engine???

Quote:Whatever for? Do you have a zero-torque cam in there? Mine idles fine at 600rpm with everything on ...

I've been reading "Tuning the A-Series Engine" by David Vizard.
That is an Anti Reversion groove on the intake valve. Many/most intake valves apparently flow better in reverse and this helps prevent that.
There are almost 5 pages written about these valves. I'm just interested in the groove.

"If the head has valves which tend to flow well in the correct direction but poorly in the reverse direction, then a tendency to reduce the negative aspects of high overlap is brought about. For instance, rough running at low rpm is reduced or even eliminated."

I have the idle set at about 1800 rpm so that the engine won't die when the headlights, heater and/or radiator fan turn on. I'm hoping for a little more stable idle at around 1200 rpm.
As far as cost, I can handle this at work. If I fark them up then i'll have to buy new ones.

Just so you don't feel lonely. . .

I have never seen an undercut this deep before. The edge of the valve doesn't look radius'd. . . (small island though)

The whole theory is that the airflow attaches to the valve and swings around, hence the radius.

I have a set in a engine that is on loan. We modified camira (GM Family II) valves to fit and added rings to the face while we were at it. (Or cut the whole face out)

Unsure of gains as the valves also have a 7mm stem instead of 8mm and this was a new head to the last engine. . . too many variables.

Seems like a good idea though, I'd do it if it isn't going to add much to the cost. . . Maybe you could do a before and after comparo for us.