Jackshaft differences

[tony g]

Im cleaning up 2 engines worth of parts and 2 jackshafts. Where the gear is for the dizzy, there are oil holes slightly ahead of the gear. One has 4 holes and the other just 2. What does this oil lube? Any major advantage with the 4 hole one?
One engine wont be running mechanical fuel pump the other will.

Cheers

Tony

[James467]

Just checked my late Sprint engine and it has just two holes, I assume they feed oil to the dizzy gear to keep it lubed.

[tony g]

Cheers James, I wonder if they only used 2 on later engines to preserve oil pressure intended for the head. It looks like they will just spray outwards and not angled to hit the gear or the petrol pump cam, but maybe just falls back down onto those areas to lube them?

Cheers

Tony

[trackerjack]

Thought it right to mention that the jackshaft is probably the most important thing to check when refurbishing a slant engine, because there is no bearing and the shaft runs direct in the block and if oil is not changed regularly will leak oil back to the sump instead of feeding to the cam the oil it needs to continue via the little flats on the jackshaft. Also inspect the gear on the jackshaft as here too you will suffer oil pump and or waterpump and distributer.
Recently I found a block that the jackshaft had worn its bore .5mm oversize, or to put it this way scrapped block, as a repair is not worth the work.

[tony g]

Good points Jon, in my case I have 2 excellent shafts and everything is minty clean

Cheers

Tony

[trackerjack]

Good points Jon, in my case I have 2 excellent shafts and everything is minty clean

Cheers

Tony

Wahoo that's good I reckon that the jackshaft say pretty much how the engine has fared in its life.
I met a guy who worked where they made the Sprint engines and he said they had loads of trouble lining up the jackshaft bores so some engines came with a fault inbuilt!

[James467]

Uh oh! I'm just about to reassemble my Sprint engine and I'm nervous!

What should I be looking for?

[tony g]

Just cleanliness of oilways really James. While rear jackjack core plug is out, try and check the bore for the shaft looks ok.

Tony