Britbike forum

Classic British Spares Klempf British PartsBaxter Cycle BritBike Sponsor SteadfastCyclesSRM Engineering Lucas Classic Motorcycle Industrial tec supply Hepolite Pistons The Bonneville ShopLowbrow Customs

Upgrade your membership: Premium Membership
New Sponsor post
2022 Classic Triumph Motorcycle Calendars
by C.B.S - 09/28/21 6:22 pm
New FAQ post
How To: Add attached images in between text
by Morgan aka admin - 10/03/21 9:46 am
Member Spotlight
Beach
Beach
West Virginia, United States
Posts: 1,074
Joined: August 2012
ShoutChat
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Top Posters(30 Days)
Rohan 87
Top Likes Received (30 Days)
koan58 19
Newest Members
Buzzkillington, zeke78, Kdkd57, Meldrew, Az Mike
11,869 Registered Users
Who's Online Now
6 members (BUSSHO, Tim Masters, desco, Mike Quinn, cycarmark, bill50cal), 27 guests, and 70 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Joined: Apr 2015
Posts: 431
P
Britbike forum member
OP Offline
Britbike forum member
P
Joined: Apr 2015
Posts: 431
In pre Unit days it was real simple, now from 63-72 there seem to be a bewildering variety of oil pumps. I have a DU 33XXX series 1966.

My parts book says my pump should be E3878, then in 1968 it's E6928, in 1970 E9421 and so on. Which models will fit my 1966? Can't find E3878 new or second hand for the life of me..the others, yes.

I have unit oil pumps with the "offset" mounting holes..the pre- units were 180 in line. . I have pump plungers (a) Scavenge 0.487/ Feed 0 .374 and another pump (b) scavenge 0.436 /feed 0.374---this seems to be correct for my year 1966 according to the Workshop Manual 650's up to 1970 and must be the mysterious E3878?.

What on earth is the other pump for? A T100 Unit as I also had parts for that lying about? It would seem odd to have a bigger scavenge diameter (0.487 vs 0.436) on a smaller engine, or did Triumph get it wrong in the literature and actually (a) is correct for my 650 since it scavenges faster but delivers the same , both feed plungers being 0.374

Don't want to blow up my rebuild, so it helps to know. Am using the factory 63-70 edition of Workshop Manual.

Last edited by Peter Gee; 06/27/17 3:48 pm.
Triumphs on eBay
Joined: Mar 2006
Posts: 5,015
Likes: 51
L
Britbike forum member
Offline
Britbike forum member
L
Joined: Mar 2006
Posts: 5,015
Likes: 51
Originally Posted by Peter Gee

My parts book says my pump should be E3878, then in 1968 it's E6928, in 1970 E9421 and so on. Which models will fit my 1966? Can't find E3878 new or second hand for the life of me..the others, yes.

I have pump plungers (a) Scavenge 0.487/ Feed 0 .374 and another pump (b) scavenge 0.436 /feed 0.374---this seems to be correct for my year 1966 according to the Workshop Manual 650's up to 1970 and must be the mysterious E3878?


650/750

'63 - '66, E3878 (Scavenge 0.437"/ Feed 0.374")

'67 - 'early' '69, E6928 (Scavenge enlarged to 0.487"/ Feed 0.374")

Late '69 - '79, E9421/ 70-9421 (Scavenge 0.487"/ Feed enlarged to 0.406")

'80 ->, 71-7317 'double check-valve' pump (same 0.487"/ 0.406").







Joined: Mar 2005
Posts: 10,714
Likes: 93
J
Britbike forum member
Offline
Britbike forum member
J
Joined: Mar 2005
Posts: 10,714
Likes: 93
And they are interchangeable...

Joined: Apr 2015
Posts: 431
P
Britbike forum member
OP Offline
Britbike forum member
P
Joined: Apr 2015
Posts: 431
Many thanks in that case...... great.....

Joined: Feb 2012
Posts: 176
Likes: 2
D
Britbike forum member
Offline
Britbike forum member
D
Joined: Feb 2012
Posts: 176
Likes: 2
Fascinating! Never knew that. A lot of suppliers just say 'oil pump suitable for 350, 500 & 650 unit construction' which aligns with JH's comment.

Joined: Jul 2011
Posts: 132
F
Britbike forum member
Offline
Britbike forum member
F
Joined: Jul 2011
Posts: 132
Yes, Peter, I gather the oil pumps are interchangeable but gotta believe the latest two valve pump, or using the four valve pump by maybe grinding the timing cover to allow a proper fit, has to be the best way to go.

Not sure the four valve pump will fit the unit 500cc bikes though.

But what do I know.

fried okra

Joined: Oct 2006
Posts: 4,230
Likes: 83
I
Britbike forum member
Offline
Britbike forum member
I
Joined: Oct 2006
Posts: 4,230
Likes: 83
Any modifications needed to the crankcase to allow for the larger scavenge and feed ports of the later pumps?

Joined: Apr 2015
Posts: 431
P
Britbike forum member
OP Offline
Britbike forum member
P
Joined: Apr 2015
Posts: 431
As far as I know Irish Swede, no, none... enlarging the feed holes would reduce the pressure when the pump plunger was enlarged to increase it......

Joined: Apr 2015
Posts: 431
P
Britbike forum member
OP Offline
Britbike forum member
P
Joined: Apr 2015
Posts: 431
Yeah like a lot of Britbike things, there is a ton of subtly and I thought the same till I started measuring pump plungers!


Moderated by  John Healy 

Link Copied to Clipboard
Job CycleBritish Cycle SupplyMorries PlaceKlempf British PartsPodtronicVintage MagazineBSA Unit SinglesBritBike SponsorBritish Tools & FastenersBritBike SponsorBritBike Sponsor






© 1996-2021 britbike.com
Powered by UBB.threads™ PHP Forum Software 7.7.5