I agree with using the whole bike engine, however for the racing fellas they need to have the block to be datsun or nissan in some cases and others have other restrictions.

On a similar but different note....
I for years have been watching the progress of a certain rotary valve head engine that was going to be produced for the K series engine used in kit cars like the Caterham or lotus 7 replicas.
The problem was that the K series are no longer made.
This rotary valve head blew the away certain K series specialists but at 7-8000 pounds a pop it is cheaper to use things like sr20det engines and pommie ford equivalents.
However I asked if he could make one for the A series and he said he would if part of the total cost was made.
This would be a geardriven or belt setup.

He has eliminated the sealing issues and can run on a variety of poor fuels and 15 to 1 compression.

http://www.rotonusa.com/roton_system.html
read through 1-5 its surely a step ahead if the sealing is solved.

For a while I had a picture of an A series speedway engine with the sohc head from an E series, but the question here was about Double OverHead Cam heads, so I didn't mention it earlier.

None the less, at least one running A series engine lives with a cammer head. I think it uses an A14/15 block with A12 crank & foreign rods & pistons to allow reliable 10,000 rpm engine speeds. [Well, reliable in a race engine sense anyway]

EDIT
Found it. Study the side of the block & oil pump. It looks like an A series to me.

rotary valves have never worked
and the K series is the biggest hunk of #### i have ever had the displeasure to repair
dazza
look on youtube for hayabusa engine in a Smart car
:)
dazza

there is a dohc head that is crossflow and is a direct bolt on to the a series block i only know of one and that is owned by one of the members on the site i do not know if he wants everyone to know so i will not mention his name but if he decides to add to the thread and give some insight on the head but he doesnt have any reall hard data to who made it or why it was made.

Feral showed us a DOHC head that bolted directly onto the A series block, however, physically bolting it on was one thing, but getting all the coolant & oil passages to work out was another.
Geting drive from the crank to the cams was yet another engineering nightmare to be addressed.

this is a head that i am to believe was made FOR the a series not to sure on how the cams where driven
[edit]
It's layout is more conventional and symmetrical like a Lotus TC head set up. It uses a chain drive and retains the original dizzy position. No-one can give me any real hard data on it's origins or who or why it was made,
that was part of the discussion i had the the owner of the head

I like the simple alloy engine L mount from a pice of L tubing on the e series headed A pic.

Rotary valves work more than well today with modern sealing solutions. They worked in the past and work well on many applications today.
Coates has their own version also.
Nothing comes close, simple, compact and run at compression ratios normal poppet valves would decintegrate for low octane fuels.http://www.coatesengine.com/technology.html

I don't want to seem too much of a sceptic on the rotary valve stuff, and nor am I looking to offend, but here's an article about the history of the rotary valvetrain...

http://www.dself.dsl.pipex.com/MUSEUM ... ValveIC/RotaryValveIC.htm

If it offered all the advantages that coates claim, wouldn't all manufacturers use them? (considering that they've been around sinced the 1930's and with current laws 15:1 compression would be very handy for economy etc).

Spending 8k of your own hard earned would be a brave experiment, but good luck to you if you give it a go.

you dont think honda knew about them, tried them and then invented Vtec and won races
if it aint winning it aint working
there are better solutions ie: the ones we drive every day
dazza

As far as I know Honda only ever experimented with an oval 8 valver bike engine with failure not the rotary valve.

there are better solutions than what we have on the road but poppet valve engines are a safe and simple bet.