67 vs 68

kildes · Sep 9, 2015

Newbie question - is there any difference in the head or barrel on the 68 p11 ranger vs the 67 p11 or are they swapable.

Thanks
Jefe

p400 · Sep 9, 2015

kildes said:
Newbie question - is there any difference in the head or barrel on the 68 p11 ranger vs the 67 p11 or are they swapable. Thanks Jefe

A part number search will show that the head and barrel are the same numbers for P11, P11A, Atlas, N15CS, G15CS......1966-67-68.
So this means all the valve gear, pistons, rods would be same.......crankcases list different.
Beware eBay sellers list many parts that are not what they describe.

kildes · Sep 9, 2015

Thanks, much appreciated!
Jefe

BillT · Sep 10, 2015

If the bike is a Ranger 750 (somewhere between P11/128646 to P11/129145), the head is actually a Commando casting, drilled for Atlas-style rocker oil feed. The heads are completely swappable, but the Ranger has those bosses on the sides of the head that a purist would pick out.

1968 P11A head

1969 Ranger 750 head

kildes · Sep 11, 2015

Thanks Bill

#1259XX originally titled when new as a 68 "P11 Ranger" in color "Blu"

Not quite as pretty as yours...

Jefe

BillT · Sep 11, 2015

P11A - 1st 124372, last 126123. 3 batches made, totaling about 1300.

Your bike, P11/1259xx, was produced in the last batch of P11As, and many of those were said to have been updated at the dealer with the Ranger decals.

This is what a Blue P11A would look like (very few blue ones) the color is an AMC Color, also used on the G80CS and the N15CS/G15CS.

kildes · Sep 12, 2015

that is my understanding as well -- that the dealers "updated" their bikes in inventory. given the number (and it is a matching numbers bike), I was surprised to see that the p11 ranger model on the original title, and given that, even more surprised to see that the bike was blue when new.

Ron L · Sep 13, 2015

If the bike is a Ranger 750 (somewhere between P11/128646 to P11/129145), the head is actually a Commando casting, drilled for Atlas-style rocker oil feed. The heads are completely swappable, but the Ranger has those bosses on the sides of the head that a purist would pick out,

Both my Ranger 750 and spare Ranger 750 engine have 3/8 inch head bolts like a Commando. My '67 P11 has 5/16 inch head bolts like an Atlas. The '67 might have had the head and barrel swapped for an Atlas one at some time, but if it is correct for a '67, then a a Ranger head would not interchange with a P11 or P11A without redrilling the cylinder for 3/8 bolts.

CanukNortonNut · Sep 13, 2015

Ron L said:
If the bike is a Ranger 750 (somewhere between P11/128646 to P11/129145), the head is actually a Commando casting, drilled for Atlas-style rocker oil feed. The heads are completely swappable, but the Ranger has those bosses on the sides of the head that a purist would pick out,

Click to expand...

Both my Ranger 750 and spare Ranger 750 engine have 3/8 inch head bolts like a Commando. My '67 P11 has 5/16 inch head bolts like an Atlas. The '67 might have had the head and barrel swapped for an Atlas one at some time, but if it is correct for a '67, then a a Ranger head would not interchange with a P11 or P11A without redrilling the cylinder for 3/8 bolts.

Hi RonL,
My P11 has the 5/16" bolts for the head and it is a Late 69 Ranger, near 40 from the end of production. My head has the bosses that BillT mentions. Could someone have modified yours to commando spec? (Not that it is a bad thing)...it is stronger. The four bolts at the spark plug location... Do you see little divots or tits on the center of the bolt heads? The one going down in the center of the head is 3/8" with a slight dome at the crown.
Cheers,
Thomas
CNN

OldForge · Sep 14, 2015

The four bolts at the spark plug location... Do you see little divots or tits on the center of the bolt heads? The one going down in the center of the head is 3/8" with a slight dome at the crown.
Cheers,
Thomas
CNN[/quote]

Those divots, domes & tits on the fastener heads have to do with the machinist who made them & how carefully the parting off cutter was centered while making a bunch of them from hex bar stock. These things were made with manual machining & nothing has the consistency of today's CNC made stuff so you can't compare models, years or series by such minor details. The more critical parts (bearing bores, etc.) were, presumably, made by the more experienced/skilled machinists.

Mark in SC

kildes · Sep 16, 2015

The head on my 68 P11A is part number 25319. To replace my damaged 25319, a friend has an atlas head 23166 (pictures below), which I believe is an earlier atlas head. I have no part books for these models as of yet but will remedy that shortly. in the interim, is the 25319 head interchangeable with the 23166? bolt size/positions, exhaust port size/angle, etc?

Thanks
Jefe

p400 · Sep 16, 2015

My advice, there are way too many 25319 Norton heads out there for sale, everyday on EBay and other sources, to look at a substitute head with subtleties no one here can explain.

kildes · Sep 16, 2015

Solid advice. This is clearly an Atlas head, and my understanding has been that the Atlas and p11, p11a heads are interchangeable. I don't have the parts books for all models. I do have this head handy and it is in good shape. I appreciated your earlier advice to beware ebay sellers, despite the fact that, as you point out in your most recent message, there are many heads available on ebay. Perhaps this head was used on a limited run of p11s or atlases.

p400 · Sep 16, 2015

here is one man's Norton head research. This may be good info , it may be bad info, It may not be enough info...you choose
http://atlanticgreen.com/nhth.htm

kildes · Sep 17, 2015

thanks for that link!

I understand that heads with identical casting numbers on the underside of the heads were machined differently for different models/model years. I've found the other numbers on the head.

Ron L · Sep 24, 2015

CanukNortonNut said:
Both my Ranger 750 and spare Ranger 750 engine have 3/8 inch head bolts like a Commando. My '67 P11 has 5/16 inch head bolts like an Atlas. The '67 might have had the head and barrel swapped for an Atlas one at some time, but if it is correct for a '67, then a a Ranger head would not interchange with a P11 or P11A without redrilling the cylinder for 3/8 bolts.

Hi RonL,
My P11 has the 5/16" bolts for the head and it is a Late 69 Ranger, near 40 from the end of production. My head has the bosses that BillT mentions. Could someone have modified yours to commando spec? (Not that it is a bad thing)...it is stronger. The four bolts at the spark plug location... Do you see little divots or tits on the center of the bolt heads? The one going down in the center of the head is 3/8" with a slight dome at the crown.
Cheers,
Thomas
CNN[/quote]

No markings on the bolt heads, they are identical to Commando. Both heads are Commando-style castings, with the oil feed drilled in the bosses on the horizontal (top) surface of the head (as is correct for Ranger heads). Both engines are Ranger serial numbers and both have 3/8-26 outer headbolts. Next time I'm at my buddies house I'll get him to dig out his Ranger he bought new and check out the bolt size.

As I stated earlier, it is possible that the head on both engines was drilled for the larger bolts (and Commando cylinders used or the originals drilled and tapped 3/8-26). I have pulled the head on the spare engine, but only one bolt on the complete bike, but the spare has flat-top pistons with valve reliefs (Commando pistons) rather than the dished Atlas style, so re-drilling is entirely possible.