The spark plug thread Helicoil failed going over Lukey heights damaging the head. As the valve seats need to be removed to effect a repair I thought it would be a good time to install larger valves, but as this is an early '85 F1 with the small Pantah valves it seems this could impossible.

Searching the web and reading through Brad the bike boy's blogs I came across this

"The other side is that they would work with really small ports because they are so long. A small port needs time to accelerate. The fact is, the 'factory' bikes used 43 and 38 valve sizes. (Is that a familiar size?) Can you imagine how sunken the valve seats are on that head? And the dome on the pistons?

Therein lies my quandary with using them on mine. They really deserve the right size valves, but my heads are the earliest F1 heads and they have 37 and 33.5 valves with 14mm spark plug holes. I can't put big valve seats in them without cracking from the sparkplug holes to the exhaust seats. If I use the smaller valves (the seats are big enough to take 39mm inlets) it might actually work OK, but then it wouldn't be anything like the original.

Oh, and there's one more problem. The cases are pre-Paso and are prone to cracking with high RPMs."

So if anyone has done this and wants to offer some advice as to what valves and how it would be appreciated. We are trying to get this done before christmas.

I'll post some pics when i can work out how.

cheers

Is this where I'll need to go?

http://www.ducatiphoenix.com/F1.htm

"........ The heads have been seriously ported and mated to the 40 mm Dellorto pumpers with Malossi velocity stacks that barely fit between the frame rails. The carbs have no chokes; just ticklers. The spark plug holes have been filled up and new holes brought farther from center to get a higher compression piston in there. The plug size is reduced from 14 to 12mm. Valve sizes are 42/44 mm...."

Cjsracing in Bristol, he can help you out.
Paul

Bristol is a bit far from Oz but thanks

I have a series 1 750 F1 also. It is currently with Ian Gowanloch in Adelong NSW having the same upgrade that you plan for your engine. Ian has all the parts on the shelf.
If you are closer to Melbourne you can also try Bob Brown. There you have it, two of the world's top Pantah race engine builders on your door step!

Ian has quite a back log to get through so try Bob Brown - I understand that he is only semi retired and may enjoy a job like this.

Re engine cases cracking - if you can screw the throttle as hard as Marco Luccinelli then there is a chance you can crack the cases. If you don't ride that hard it won't be a problem.

Cheers,
MikeA

'Nearly forgot, you also have Brook Henry of >> Vee Two << in Western Australia who is also one of the world's great Ducati engineers. He can also fix you up with a set of >> Race Cams <<

Thanks Mike, I know of both Bob and Ian. In fact the engine in this bike is a Bob Brown 836cc engine similar to the Magee bike. The heads have had some work on the ports but it is still using the standard valve size and 36mm PHF's. The motor has heaps of grunt but runs out of puff at 7000 and I was hoping to give it a little more legs before the end of January when we go to the Island Classic to be thrashed by the P6 RC30s/OWO1s/GSXR1100s etc. However given the time and budget restrictions neither of those two are options. Instead we will do it ourselves, which is why I was curious if anyone had done something similar.

The plan at present is to insert a 12 mm spark plug and widen the inlet valve to 41mm. As the seats will have to be recessed I expect the valve stem will have to be shortened. Although I think the 41mm Ducati monster/ss valve is shorter than the 37. Then of course there is that lifter groove to line up.

I suspect changing the valve angle would also involve the creation of new rocker arms, so that wont be happening.

I have a set of TT2 cams I was thinking of installing as well in the attempt to get more speed.

cheers

PS Your right I'm no Marco Luccinelli, but it is on its second set of cases.

Sounds like you are no slouch either!

Good luck against the Jap bikes!

Cheers,

Very much the slouch Mike