building the fantasy carby 750 top-end

[carbmon]

There's been some posts recently related to the heads and cams that'll allow a carby 2V 750 to breathe and gain a few meaningful HP with proper setup.  Brad Black's bikeboy.org website is a tremendous resource about this modification (thank you, Brad, for sharing some of your wealth of experience with the Ducati world!!).

One problem is finding the correct pieces given that heads and cams may have long been separated from their original bike.   Discounting unscrupulous sellers, more often than not the problem is that sellers simply don't know what they really have and there's weird combinations of heads and cams out there, maybe due to parts-shuffles by PO's of the pieces.

So the questions, as if I might want to try to assemble this fantasy top-end setup ….

++ Is there any specific marking that clearly identifies the desirable early 900cc head with 43/38mm valves?  Where are the oft-mentioned “W” and “V” marks found on the head and can anyone post pics of those?

++ Is there any specific marking that clearly identifies the cams that should be matched with these heads?  Brad's site has the specs in a great table about Ducati cams, but sparse info about markings those cams may carry.  Again, anyone happen to have pics of the location of those markings?

++ Or, is finding absolute telltale markings just too much to expect because Ducati was fast-and-loose about markings matching unique parts specs?

Finally, just to be sure …. There seems to have been a period of question about stud spacing and whether the early 900 carby big-valve heads can bolt-up to the 750 cylinders.  Is it correct that these heads do align and bolt-up to the 750 carby cylinders (given that squish, cam timing, tuning, etc, etc all have to be properly setup in the process)?

Thanks!

[motoxmann]

 

all great questions, I'd love to know all this myself

[Duck-Stew]

Belt-drive 750 heads will NOT swap onto a 900 & visa-versa.

The W and V are clearly marked and (there was no fast-&-loose markings), all V's are V heads and W's are W heads.

620 heads will pep-up a 750 a good bit, but to really kick it in the ass... 

Locate some 695 heads and drop in some 11:1 Ferracci pistons. 

[Raux]

Belt-drive 750 heads will NOT swap onto a 900 & visa-versa.

The W and V are clearly marked and (there was no fast-&-loose markings), all V's are V heads and W's are W heads.

620 heads will pep-up a 750 a good bit, but to really kick it in the ass... 

Locate some 695 heads and drop in some 11:1 Ferracci pistons. 

did anyone ever find out if the 696 heads fit?

[carbmon]

Belt-drive 750 heads will NOT swap onto a 900 & visa-versa.

OK, so this is the stud spacing difference between "small block" 2V and "big block" 2V to use Brad's terms.  On a more careful umpteeth re-read of his "Minnie" build-up report I finally comprehend that he was always working with 750 heads on the 750 block, fitting 42.5/37 (cut-down 38mm exhaust valves) and installing a 900 cam in the 750 heads.

Thank you for the needed kick in the head (so to speak   ).

The W and V are clearly marked and (there was no fast-&-loose markings), all V's are V heads and W's are W heads.

Largely moot given the above, but I'm still curious about where the markings are found on both heads and cams.  Looking at my heads mounted on the bike (so I'm not able to see the bottom of the casting) the only marks I see are “80” stamped into the side of the vertical cylinder 'cambox' and “1P” stamped into the same location on the horizontal cylinder.  Looking at various forum and eBay posts of heads for sale, many with close-ups of casting markings, I've yet to see a “V” or “W”.

Are the cams stamped on the end of the shaft behind the pulley or on the 'bare' end (as in "VHT" / "OHT" for early 900ss cams)?

My “fast-&-loose markings” question was prompted by a post by Ducatiz in the Cam Identification thread â€" I guess that had to do with the combination of head and cam between certain bikes, not the markings on each component.

620 heads will pep-up a 750 a good bit, but to really kick it in the ass... Locate some 695 heads and drop in some 11:1 Ferracci pistons.

Well that sounds interesting, can you steer me to any build / dyno results threads about those evil approaches.

Thanks for the clarifications and teasers!

[Raux]

696 is 88 bore.  44mm intake. 38.5 exhaust

what's the bor on the 750

[ducpainter]

The W and V designation only appear on the 900 motors.

[koko64]

Yeah, the engine stud spacing between the 750 and 900 heads is a mile out.
The newer small case heads are a possibility. I think there was a thread where someone found the late small block heads fit, but there was a question about deck height, piston clearance, rod length, etc. Cant remember who found out what.

The V or W marks are on the front left hand side of each head, between the valve inspection cover and cam end cap.

Doug Lofgren has also done a hot 750. See his old MPS site.

[Speeddog]

did anyone ever find out if the 696 heads fit?

696 heads won't bolt up to the 750 barrels, as they use head gaskets.
And the exhaust port is a different configuration, so that very likely won't work either.

Stew and I built that 750 in late '07.
695 heads with a little port match/cleanup, Ferracci 11:1 pistons.
IIRC, it already had a carb kit in it, and it did have a light flywheel in it too.
That was a snarly little 750, for sure.
No dyno info.

695 heads have the same size valves as the 900, cams are shorter duration and less lift, not necessarily worse though.

[koko64]

So the options for a more straight forward fit are 900V cams and valves or 695 heads. What do the 695 heads go for up there? Down here I think it would be cheaper to get 900 cams and valves.
With hi comp and good cams and valves, a 750 could embarass a  stock or stockish 900, I reckon. I like how they don't choke at the top end, and many say they are a sweeter engine.
What do you say Speeddog, good project for your bike?

[carbmon]

Sounds like even though the 750 is an 88mm bore same as the 695, full size 900 big valves may not fit in that head (Minnie had a cut-down ex valve) maybe due to angle&/or head shape.  Obviously it can be done and gain was on the order of 10% in Minnie's case.

The 695 swap as described above might be a bit more straightforward, assuming that combustion chamber is designed to take advantage of the larger valves.  What manifolds/runners were used 'tween heads and carbs on that project?

[Speeddog]

~~~SNIP~~~
  What manifolds/runners were used 'tween heads and carbs on that project?

Standard 750 carby runners, manifolds, carbs, etc.

[Speeddog]

~~~SNIP~~~

What do you say Speeddog, good project for your bike?

I've been tempted, as I've got all the bits to do it, save for the hi-comp pistons.

But that's where it goes sideways.
I'd have to pull the heads off of my 695 engine that's complete other than a clutch.
And then buy the hi-comps.
And pretty much re-create Brad's 750, IMO.
I've got the bits to try it with 900ie cams, and ST2 cams.
Which would be interesting.
But I've got nobody that will pay for the experiment, so it's tough to justify.

For a little bit more money and effort, I'd buy 800 hi-comps, tear the 695 down, and install the 800 crank that I've got.
Or even a DS1k crank I've got.
Ending up with an 803 or 870 small-case 6-speed.

[koko64]

I've been tempted, as I've got all the bits to do it, save for the hi-comp pistons.

But that's where it goes sideways.
I'd have to pull the heads off of my 695 engine that's complete other than a clutch.
And then buy the hi-comps.
And pretty much re-create Brad's 750, IMO.
I've got the bits to try it with 900ie cams, and ST2 cams.
Which would be interesting.
But I've got nobody that will pay for the experiment, so it's tough to justify.

For a little bit more money and effort, I'd buy 800 hi-comps, tear the 695 down, and install the 800 crank that I've got.
Or even a DS1k crank I've got.
Ending up with an 803 or 870 small-case 6-speed.

Fair enough.
The newer motor will be better I guess.
I need a wealthy sponsor too.

[H-2 CHARLIE]

SPEEDDOG  > would hi comp pistons and big cams work with my F.I. M750 ?