Turn your head

[paso750]

I`m wondering if cylinder stud distance is the same.

[ducinthebay]

I know that the 900 motor has different spacing than the 750 motor. I once looked at putting 900 heads with the bigger valves on a 750 motor, but the cylinder stud spacing is different, so it wouldn't work.

The newer 800 heads have the larger valves of the 900, and the spacing of the 750 motor,so they would fit on. But unfortunately the 800 has a completely different piston design, so not an easy conversion. (not enough compression in the end) Maybe a set of 800 hi-compression pistons would work. I have those 800 heads if some one wants to try and make that conversion. (cheap)

If the 500 head would fit, the next obstacle would be the squish band, and matching that between both cylinders. Drop Steve @ loudbike a note, he would be able to tell off the top of his head.

Cheers,

[ducbertus]

Those heads are not that different.
bolt size should be the same. the stroke and the diam. of the pistons are bigger on the 750. and the size of the valves I guess.

I'm not quiet shure there's enough material to reshape the ports.
but there Pantah's enough in Holland to compare this

Ducbertus

[ir_joep]

HI,

I might get hold of two F3 heads...
What is the forums opion? Owner says it will fit a 750 engine and only in need of adjustment of the valve sizes...

Thanks for your wisdom.

Cheers Joep

[ducbertus]

Hi Joep,

I think they will fit, as the production system of Ducati relays heavily on interchangeable parts/casting. certainly those days. and the casings of all the Pantah based are the same with several times increase of bore and/or stroke.

Ducbertus

[loudbike]

Hi There:

Board member Joep Grooten emailed me a while ago regarding this thread (sorry it too so long to jump in Joep) and I've had some experience that's relevant to the discussion. I think Joep connected with me though the Cadillac project (a hot-rodded '90 Sport with a 900Ss engine), but what might shed some light is the approach we took with creating a big-bore engine for my F1. After looking at all the angles, we felt that we were best served bolting the F1 heads onto the 900SS engine and although it took a bit of machining, it was far easier than any of the other alternatives. In the end, we took a 900SS bottom-end, used a lightened 748 crank, 996 rods and 944-kitted air cooled barrels from an '00 900SS. We machined 11mm from the bottom of the barrels; which meant we had to create a pressed in support for the front cylinder return o-ring. The stud spacing is different so the F1 cylinder head holes were "ovalated" using a special milling bit. Oversized wrist pin bushings were required in order to mate the rods to the pistons. Here's what we missed: the combustion profile of the F1 heads is "hemi" while the 900SS Pistal piston is "bathtub", so if you're going to do this you need to either machine the piston or profile the combustion chamber to run the correct squish. We did neither so we run a very conservative squish.

Still goes like a scalded cat. Info on both bikes at http://www.loudbike.com

[ducinthebay]

That's what I like about you Steve, always taking it so much farther than the average hot-rodder would have ever thought to. I love the concept of the big bore motor in the F1, but what about just putting F1 heads ( or for that matter, Pantah heads) on a 750 Paso/Sport motor? His concept is to build a replica TT starting with the 750 motor. Is there much difference (any?) between an F1 bottom end and the Paso/Sport bottom end? Is it basically the heads that differentiate these two motors?

Great to have you on the site. If I had the budget, time and commitment, I'd be right there with you. I cried when you took a perfectly good Sport and disassembled it. But then I bought some of the parts from you off e-bay, and read every word about the transformation on your blog. Thanks for setting the bar so high when it comes to hot-rodding an old bike, doing a fine job of documenting it.

Cheers,

[higgy]

Interesting project

[loudbike]

That's what I like about you Steve, always taking it so much farther than the average hot-rodder would have ever thought to. I love the concept of the big bore motor in the F1, but what about just putting F1 heads ( or for that matter, Pantah heads) on a 750 Paso/Sport motor? His concept is to build a replica TT starting with the 750 motor. Is there much difference (any?) between an F1 bottom end and the Paso/Sport bottom end? Is it basically the heads that differentiate these two motors?

Great to have you on the site. If I had the budget, time and commitment, I'd be right there with you. I cried when you took a perfectly good Sport and disassembled it. But then I bought some of the parts from you off e-bay, and read every word about the transformation on your blog. Thanks for setting the bar so high when it comes to hot-rodding an old bike, doing a fine job of documenting it.

Cheers,

Thanks for the compliments - it's all fun.. The reason I took the Sport apart was to use the bottom end on Shannon's F1; which had an earlier "A" bottom end that blew the mainshaft bearing through the cases. I simply bolted her F1 heads on to the Sport motor. Note that - as with my F1, you will have the combustion chamber / piston difference to deal with (in Shannon's case, I used F1 pistons and cylinders). The Sport and Paso bottom ends are identical to the later series F1; save for the ignition and the swing arm bosses (on the Paso). Very late series Allazurra (GT) engines fall into this category as well. So yes, you can bolt the F1 (good luck finding them) or Allazurra heads onto the Sport bottom end although you should swap to the older-style pistons when doing so.

[paso750]

there was an ebay auction lately from a guy who modified heads from a 500 Pantah to fit 750F1 cylinders. Valves were the small ones from the 1st series F1. http://cgi.ebay.de/Ducati-Pantah-750-F1 ... 414e6d1079
There`s a 804cc F1 on ebay too. According to the seller they used crankshaft and conrods from a newer 800 series engine. Not sure what pistons they used.
interesting what`s all possible.

G.

[ir_joep]

Yes the answers from the guru...

Thanks very much Steve for joining us. (Hope for the future as well).

My initial toughts were to modify the vertical sport (or paso) head to become a F1 head. This would require at least a new camshaft and matching the valves sizes. The valves have to change on the horizontal as well so both head have the same valve sizes for inlet and outlet and chamber shape. But what else would be needed?
Is it possible for the exhaust channel of the sport to become an inlet and for the inlet channel of the sport to become an exhaust????

I can not tell because I do not have the f1 and sport heads on the shelves.

Maybe someone has?

Thanks for helping

Joep

[ducinthebay]

Joep,
I think you may need to sacrifice a spare old head to answer your question completely. Get an old head and bandsaw it into sections through the ports or other critical paths. This will tell you what the wall thickness are, where the oil lines run, where you need to add material, and where you need to remove material. An experienced head porting shop should be experienced with welding and grinding of heads. It won't be cheap, but I can see how it could be done. You would do well to have the front head ported similarly at the same time so the flow characteristics match. I think the first thing is to see if the geometry of the cam to rocker pivots, to valve faces is symmetric. If so, then you should be able to move forward. Are intake rockers and exhaust rockers interchangeable in a head? That would be your first clue.

Anyone have a spare rear head to donate to Joep for science?

Cheers,

[paso750]

Joep, you have pm

G.