Britbike forum

Classic British SparesKlempf British PartsBaxter CycleBritBike Sponsor SteadfastCyclesThe Bonneville ShopLowbrow CustomsGirling Classic MotorcycleLucas Classic MotorcycleHepolite PistonsIndustrial tec supply

Upgrade Your membership! Premium Membership Gold Membership Vendor Membership

New Sponsor post
5% Off Everything for Brit Bike Users
by The Bonneville Shop - 12/30/21 4:54 pm
New FAQ post
Manuals on DVD - Buy 4 for 3
All 4 DVD Manual
Member Spotlight
Matchman62
Matchman62
Armidale ,Australia
Posts: 136
Joined: May 2002
ShoutChat
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Top Posters(30 Days)
Top Likes Received (30 Days)
NickL 24
Lannis 23
Cyborg 21
Newest Members
ToddK, JohnS_au, Colin MacQueen, mark denny, Restoration Mike
11,991 Registered Users
Who's Online Now
6 members (semprini, quinten, dave thomas, L.A.B., Rohan, Binksy), 33 guests, and 15 robots.
Key: Admin, Global Mod, Mod
Forum Statistics
Forums35
Topics75,312
Posts758,733
Members11,991
Most Online14,755
May 5th, 2019
Previous Thread
Next Thread
Print Thread
Joined: Apr 2015
Posts: 444
P
Britbike forum member
OP Offline
Britbike forum member
P
Joined: Apr 2015
Posts: 444
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: 5,143
Likes: 62
L
Britbike forum member
Online Content
Britbike forum member
L
Joined: Mar 2006
Posts: 5,143
Likes: 62
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: 10,781
Likes: 145
J
Britbike forum member
Offline
Britbike forum member
J
Joined: Mar 2005
Posts: 10,781
Likes: 145
And they are interchangeable...

Joined: Apr 2015
Posts: 444
P
Britbike forum member
OP Offline
Britbike forum member
P
Joined: Apr 2015
Posts: 444
Many thanks in that case...... great.....

Joined: Feb 2012
Posts: 190
Likes: 2
D
Britbike forum member
Offline
Britbike forum member
D
Joined: Feb 2012
Posts: 190
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: 4,391
Likes: 112
I
Britbike forum member
Offline
Britbike forum member
I
Joined: Oct 2006
Posts: 4,391
Likes: 112
Any modifications needed to the crankcase to allow for the larger scavenge and feed ports of the later pumps?

Joined: Apr 2015
Posts: 444
P
Britbike forum member
OP Offline
Britbike forum member
P
Joined: Apr 2015
Posts: 444
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: 444
P
Britbike forum member
OP Offline
Britbike forum member
P
Joined: Apr 2015
Posts: 444
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
British Cycle SupplyMorries PlaceKlempf British PartsBSA Unit SinglesPodtronicVintage MagazineBritBike SponsorBritish Tools & FastenersBritBike Sponsor






© 1996-2022 britbike.com
Powered by UBB.threads™ PHP Forum Software 7.7.5