Difference between 3 start and 6 start oil pump?

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Hey,
Every time I put on six start in replace of 3 start I moved overhead rocker feed to bottom of the timing chest ala commando style, scrolled or not, I have ruined more cams by lack oil flow from head then any soft cam problems ever encountered.
Never ran down Atlas cam tho!
One trick was open oil tank on Atlas and put you finger on oil return momentarily to flush oil to head, now who showed me that trick :)
nortonmark
 
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FWIW .... My '63 Atlas, actually a '62 build date, came from the dealership fitted with a 6 start oil pump. As I am the original owner, I can attest to that fact, curious as it is. The rest of the rocker gear is the scrolled type, typical of the 3 start systems. I have no idea whether the bike was a special Norton build, or a Berliner modification. From what I know of the dealer, he most likely DID NOT make the modification.

In 85K miles, I have not had any problems with this combination (6 start pump + scrolled rocker spindles). Thus, I would say, based on this experience, adding a 6 start pump + drive gear to older engines with scrolled rocker spindles should pose no problems.

Slick

PS: the easiest way to distinguish 3 vs 6 start worm gears, is to look at the worm gear face straight on (as if viewing an analog clock). The "starts" are where the gear lands begin their cut. As you view around the circumference, there will be 3 or 6 starting cuts.
Yes, my 1962 Atlas has a 6 start pump and scrolled spindles, but as to whether it was supplied like that, I don't know. I have had no issues with over oiling.
 
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There appears to be some dispute as to when the 6 start worm oil pump was supplied by Norton.

I suspect that, as it was officially fitted from 1966 on, according to the green Norton workshop manual, British suppliers like Dunstall etc, supplied them in their catalogue, and I suspect that Doug Helne fitted them on their overhead rocker supply 500 Domiracer from 1961. Feel free to correct me if I’m wrong.
 

mdt-son

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There appears to be some dispute as to when the 6 start worm oil pump was supplied by Norton.

I suspect that, as it was officially fitted from 1966 on, according to the green Norton workshop manual, British suppliers like Dunstall etc, supplied them in their catalogue, and I suspect that Doug Helne fitted them on their overhead rocker supply 500 Domiracer from 1961. Feel free to correct me if I’m wrong.

As seen in the NOC tech digest:
"From engine No. 116372 the con rods had a strategically placed hole drilled in order to squirt oil under pressure onto the cylinder bores. At the same time all models were fitted with a six-start worm drive on the oil pump, supposedly giving double delivery. Along with enlarged oilways, the rockers were now pressure fed from the delivery side of the pump. "

Engine no. 116372 was built at AMC in February 1966.
Enlarged oilways is underpinned by all NHT receiving new junction block and oil pipes.

1971-1976 oil pipes were 3/8" OD (5/16" ID) and no stepped sleeves were fitted on Commando models. Hose size was 3/8" ID and ferrules were fitted.
1966-1970 oil pipes were 3/8" OD (5/16" ID) having a stepped sleeves of 1/2" OD on all models. Hose size was 1/2" ID and ferrules were fitted.
1964-1965 oil pipes were 5/16" OD (1/4" ID) and stepped sleeves of 1/2" OD were fitted on G15 models. Hose size was 1/2" ID and ferrules were fitted.
1949-1965 oil pipes were 5/16" OD (1/4" ID) and no stepped sleeves were fitted on Dominator models. Hose size on Dominator models was 5/16 ID x 5/8" OD and ferrules were fitted.

-Knut
 

mdt-son

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Hi all.

Following a vendor discussion, I just completed a review of the different Norton/AMC/NV pumps offered since the early 50's.

Models 50/ES2
Pump assy: NM15521. Features: Narrow internal gears. Low capacity. 3 start gear. Pump shaft at rhs in frontal view.
Worm driving gear: NM13778. Features: 3 start, small diameter mainshaft thread.
Worm driven gear: NM10101A. Features: 3 start.

Models 88/99/88SS/99SS, AMC G3/G80 [->07/66]
Pump assy: NM15522. Features: Wide internal gears (.190"/.310"). Medium capacity. 3 start gear. Pump shaft at lhs in frontal view.
Worm driving gear: NMT2076. Features: 3 start, large diameter mainshaft thread. (Superseded on AMC singles: 030173)
Worm driven gear: NMT2077. Features: 3 start.

Models 650 Manxman, 650SS, Atlas, G/N15 [->02/1966].
Pump assy: NM23111. Features: Wider internal gears (.250"/.397"). CEI thread on shaft. High capacity. 3 start gear. Pump shaft at lhs in frontal view.
Worm driving gear: NMT2076. Features: 3 start, large diameter mainshaft thread.
Worm driven gear: NMT2077. Features: 3 start.

Models 650SS, Atlas, G/N15 [02/1966->], P11 [03/1967->], 750 Commando [04/1968->]
Pump assy: NM25396 (supersedes to 066193). Features: Wider+ internal gears (.250"/.406"). CEI thread on shaft. Very high capacity. 6 start gear. Pump shaft at lhs in frontal view.
Worm driving gear: NM24733 (supersedes to 067890). Features: 6 start, large diameter mainshaft thread.
Worm driven gear: NM24732 (supersedes to 067889). Features: 6 start.

Model G80/85CS [08/1966->].
Pump assy: NM25450. Features: Wider+ internal gears (as NM25396). High capacity. 3 start gear. Pump shaft at lhs in frontal view.
Worm driving gear: 030173. Features: 3 start, large diameter mainshaft thread.
Worm driven gear: NMT2077. Features: 3 start.

Models 750/850 Commando [09/1970->].
Pump assy: 063037. Features: Wider+ internal gears (as NM25396). UNF thread on shaft. Very high capacity. 6 start gear. Pump shaft at lhs in frontal view.
Worm driving gear: NM24733 (supersedes to 067890). Features: 6 start, large diameter mainshaft thread.
Worm driven gear: NM24732 (supersedes to 067889). Features: 6 start.

Model 850 Commando Mk3 [09/1974->].
Pump assy: 066193. Features: Wider+ internal gears (as NM25396). UNF thread on shaft. Large seat for rubber seal. Very high capacity. 6 start gear. Pump shaft at lhs in frontal view.
Worm driving gear: NM24733 (supersedes to 067890). Features: 6 start, large diameter mainshaft thread.
Worm driven gear: NM24732 (supersedes to 067889). Features: 6 start.

I trust this compilation is of use to some.

-Knut
 
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texasSlick

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@Knut Post #24
"From engine No. 116372 the con rods had a strategically placed hole drilled in order to squirt oil under pressure onto the cylinder bores. At the same time all models were fitted with a six-start worm drive on the oil pump, supposedly giving double delivery. Along with enlarged oilways, the rockers were now pressure fed from the delivery side of the pump. "


My engine Number is 102833, and it has the "squirt" holes and 6 start oil pump. As I stated in Post #10, I bought the bike new and that is the way it came. I speculate the bike was a special build for evaluation by Berliner. Berliner had the bike for nearly a year before it appeared at my local dealership. According to NOC records, the bike was dispatched 21 May 1962 and I bought it April 1963. That is a long time to cross the pond and arrive at a dealership. The NOC records do not mention any special modifications. FWIW, the bike also came with dual Amal Monoblocks, and could run away from my brother's stock '65 Atlas.

@Knut Post #25
A great compilation of data! Thanks for that.

Slick
 

ES234

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This may help. From my archives. :)
 

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texasSlick

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assuming the pix are correct, the outer shape of the pumps around the bottom mounting holes are distinctly different, the 3 start is notched (clearance bevel on one end of the pump body) vs rounded on the 6 start

then again, this one on ebay advertised as year 70 is notched
"1970 NORTON COMMANDO COMPLETE OIL PUMP ORIGINAL OEM 06-3037"

this notched one advertises fitting
"NORTON-OIL-PUMP-ATLAS-77-88-99-COMMANDO-750-850-COMBAT-FASTBACK-ROADSTER-N15-"


stumbled this
http://centralcoastclassicmc.com/NortonOilPumps.htm

new one here shows no bevel
https://www.classicbritishspares.com/products/norton-commando-oil-pump-06-6193
ad sez


https://www.accessnorton.com/NortonCommando/p11-p11a-750-ranger-engine-thread.18418/#post-274466

The purpose of the bevel is a mystery to me. Obviously, it is for clearance, but nothing in my 1962 timing chest requires such a clearance.
My original oil pump was a six start and had a bevel. My present oil pump came from an early Commando which I bought for parts. The early Commando pump has a bevel and is six start, and is visually identical to the original pump. Perhaps micrometer measurements may find a difference. As far as I can tell, one can swap out a bevelled/non-bevelled pump into an Atlas/Dommie or Commando without concern.

Slick
 
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The bevelled base plate is for singles, but can be used for twin pumps. The wide gears are on drawings dated 1959.
 

mdt-son

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The bevelled base plate is for singles, but can be used for twin pumps. The wide gears are on drawings dated 1959.
No, the bevelled base is for small twins (Navigator and Electra), p/n 15522 (3 start worm gear, medium capacity). The internal gears are less wide than those in the high capacity pump p/n 23111 (3 start worm gear, high capacity) , which was succeeded by 25396 (same housing albeit 6-start worm gear, very high capacity).
There are plenty of oil pumps for the big twins around, so why take a chance and fit an underrated oil pump?

-Knut
 
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The single would have used the same pump internals from 1960 - on, I suspect many owners back in the day when pumps were scarce would have fitted and mixed and matched what ever components to get a working oil pump. The bevelled plate is needed for the single - why do you think I go to the expense of getting the plates machined.
 

mdt-son

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Madnorton, it seems we are adressing different parts. Slick and I were adressing bevel of the oil pump housing. You are talking about the bevelled plate. I guess you are referring to the brass end plate?
Interesting info about the single pump (15521) internals. It makes sense for Norton to use internal gears shared by pump type 15522.

-Knut
 
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