New 250 Project Adventure

[Snakeoil]

Okay, let me try to recap here.

Bikester, you think that the 10mm hole might be for a second plug. Somebody I know that races Duc singles said that is where he puts the plug when he dual plugs a head. Are you saying this could be a Mach 1S head or just mentioning it that the hole might have been for a plug rather than a compression release?

Jon, from your reply I get the feeling that the compression release is the give away to it being a Spanish 350 head. Did the Spanish 350's have a 29mm intake port or did somebody open up the port on this head?

Were the longer teeth and shorter exhaust snout additional indicators that this is a Spanish 350 head? Trying to get smarter here. If not, do those features have any significance to help date or ID the head?

When I got the head, the remnants of the compression release were still in place. The housing and valve were there along with the spring. The actuating parts were missing.

Thanks,
Rob

[Jon Pegler]

Regarding your no.2 head ,I don't think the second hole is for a second spark plug, even though that's where they are usually fitted.
If you check the thread, you will find that the hole has a coarser thread than a 10mm plug.
I can't remember exactly, but I think the spark plug thread is 10 x 1.25, whereas the compression release thread is 10 x 1.5
Try putting a 10mm plug in the hole and see if it goes in easily. If it doesn't, it's the coarser compression release thread.
Another clue to your no. 2 head being Spanish is the casting itself.
The higher projections along the front upper part of the head, together with the fin coming off the centre of the rear oil drain hole are clear indications of a Spanish head.
All the widecase 350 Road models came with the 29mm ports and large valves as did the Stradas, Forzas and Ventos.

Jon

[bikester250]

Rob,
I'm not an expert on all the ins and outs of Ducatis (let alone the Spanish production).
Based on the valve sizes I think it could be a Mach 1 or Diana head. I didn't know that there were 250 Ducati singles made with compression releases; I've never had a problem kicking mine over and I'm 71 so I wouldn't have thought the 250s would have needed a comp release.
Phil

[Snakeoil]

Thanks Jon. Appreciate the detailed feedback.

I was thinking that since this one had some porting work done, it might have been a hot-rod with high compression and needed a CR. From what I've learned, although the 250 does not need a CR to start it, it makes life much easier for the kick start assembly which is not hte most robust in the world.

My intention is to use a CR valve cover to help the kick starter survive.

I would assume that the 350 head might be of interest to someone racing a 250 or restoring a 350. Without the right cam and high CR, I would think that the bigger valves would be a waste.

regards,
Rob

[Ventodue]

... together with the fin coming off the centre of the rear oil drain hole are clear indications of a Spanish head.

As shown here:

Mototrans and Bologna heads.jpg

[Snakeoil]

Thanks for that clarifying pic, VD. I hope my aging brain still has room to store this stuff. It's packed with useless info like the words to the Mr. Ed theme song.

While on this topic, I may find that both valve seats and guides will require replacement. Been down this road with Brits and it can get ugly. Manual makes the seat replacement sound like a snap with a little heat involved. Books says to drive out the guides cold. What has been the experience here with these two processes.

I have a good machine shop, well versed in various engines, but no Ducati specific experience. Is there a preferred shop in the US for machine work?

regards,
Rob

[Bevel bob]

The Spanish built 24hours had big valves ,could be one of those?, I would value a valve lifter on my 250 as narrow case motors give the kickstarts a hard time. For road use I would be happy to use a 27mm carb ,the 29 mm carb probably gave a few mph at max speed but sacrificed the mid range to do it.A pumper carb would work well.A 27 SSI works well and looks the part.

[Jon Pegler]

Sorry Bob, but you can't fit a 24 Horas head onto an Italian 250.
The spacing across the head bolts is 65mm on a Horas head, compared to 76mm across the head bolts of an Italian 250 head.
Also, the Horas head has ribs cast into the top of the head casting, unlike the smooth casting on the Italian head.
The head casting in Snakeoil's no. 2 photo is almost certainly a 350 Road head, a head frequently seen in the US.
Some of the Road cylinder heads had a small 'R' stamped by one of the head bolt holes, as a further indication of their origin.

Jon

[Snakeoil]

Glad you mentioned markings, Jon. I meant to ask about that. I noticed some stamped numbers as I was scrubbing the heads.

I started to edit this after taking a look at the heads only to have my computer or my internet connection fart and I lost everything I typed. So, I'm going to try again now that I've let it go.

Took a look at the heads. Found some markings and another difference.

Head #2, the one Jon says is a Spanish 350 Road head had a "P" stamped on top of the bevel tower. Here's a pic



Also noticed that the gasket surface at the head to cylinder fit is different. #2 has a larger surface area and the two extended area have dowel pin holes in them. The head bolt pattern and other ports are identical to the Monza heads. Here is pic of #2 on the left and a Monza on the right.


The Monza heads are marked as well. My guess is these are inspector stamps. The markings on the top of one head matches the marking on the bottom fin, yet on the other head, the top markings do not match the bottom fin markings. Again, my guess is two inspectors inspected the latter head.

#1



#3



And the head from the engine found in the dump just fell out of the running. Found a broken fin as I was giving it a closer look.
regards,
Rob

[Snakeoil]

Cleaned some more parts and set aside the good bits for either the engine build or future spares. Cleaning parts, especially in the winter with no heat in the shop until I fire up a propane heater or my old Ker-o-sun, is not my favorite thing.

So, just to remind myself why I'm torturing myself, I try to end the day on a positive note. Today, decided to make a few things pretty. This should keep me motivated for a few weeks.



regards,
Rob