The following warnings occurred:
Warning [2] Undefined variable $search_thread - Line: 60 - File: showthread.php(1617) : eval()'d code PHP 8.1.31 (Linux)
File Line Function
/inc/class_error.php 153 errorHandler->error
/showthread.php(1617) : eval()'d code 60 errorHandler->error_callback
/showthread.php 1617 eval




Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
2 bearing crank in 3 bearing case
#1
Hi there,
I have purchased and A7 engine for a special I am building. It has  a Hadley crank & rods, New block by 7 County Austins, racing pistons from The Seven Workshop, camshaft from the A7 Club in Melbourne, and Mini valves.
Apparently, it has run the No.1 big end twice in 600 miles.
I am dismantling it to get the journal built up and reground, but I am curious about the location of the oil jets in relation to the scoops/recesses in the crankshaft? They don't appear to line up with the crankshaft recesses.
Has anyone any experience with this scenario?
Many thanks,
Keith Huh
Reply
#2
You have to use 2 bearing oil jets.
Reply
#3
Don't know what the Hadley crank oil pockets look like but many advocate grinding them out larger on splash cranks to encourage oil in to them.Also carefully bending the jets to align with the pockets better.
Check the oil gallery into the journal and sludge trap if there is one.Maybe fit an oil filter and magnetic sump plug too.
Reply
#4
I have found that none of the newly made crankshafts I have fitted are symmetrical in this area.

The best that can be achieved is a central position that misses both troughs, statically. Austin cranks are perfectly symmetrical in this area and jets line up on both sides. Even with the asymmetrical positioning on the new cranks, little problem is ever reported, this includes the several hundred I have fitted and makes me think that lubrication at revs come more from mist than a little low pressure oil jet.

There does seem to be an issue with longevity on 1.5” splash cranks using shell bearings, I have no experience in using such but have seen and heard of the problem from many.

Something else to consider is that original Austin rods have oil escape holes drilled at the top of the bearing so fresh cool oil is constantly circulating through, many of the new shell bearing rods do not have these escape holes and I would be interested to hear from others if this may be part of the cause.

You can retain the three bearing jets happily or fit the earlier (and larger) two bearing ones - the change of design raised the pressure to accommodate feed to the centre main bearing - which you no longer have.
Reply
#5
I always drill shell rods fitted to a splash crank for oil flow through the bearing and check side clearance you need the oil flow to cool the bearing shells. As Rory says none of the splash cranks the oil troughs are in line with reshaping the trough and using 2 bearing drilled jets adjusted by bending you can get the oil to hit the inside edge of the trough on one side of the crank and the outside edge the on the other side on several of the race engines I have built this has been successful.
Terry.            
Reply
#6
Hi Keith,

Hadley Cranks have never made any splash fed cranks, only ever pressure fed.

Some time ago there were some cranks around that had the jet troughs at 6.125" centres and not 5.25" that is required.

Hope this helps.

Peter Pearson
Reply
#7
I would think the old 750MC idea of a second pair of oil jets at the bottom of the crankcase pointing upwards is the ideal solution.
One set of jets would be directed to one pair of pockets and the other jets aimed at the other pair of pockets.
Details are either in the 750 Companion or the Special Builders Guide.

I have an 1 1/2" splash fed crank which I believe is an Allen Crank with Nippy Rods. When I find it again I will measure the pocket centres.
Reply
#8
Many thanks for the helpful advice. The crankshaft has "ACS 09/10-14" etched into it if that assists in identification?
I can see that I'll probably have to bend the jets carefully and drill the conrods for better lubrication.
It's pretty hard to assess where the jets are spraying the oil, but I guess a length of wire inserted through the jet should give some indication of their direction? The engine was assembled by an acknowledged expert in that field.
Also, I'm finding it difficult posting photographs?
Thanks again,
Keith
Reply
#9
This territory been canvassed before. It does seem strange to vent a bearing just as the main load suporting film (at normal revs) is required to form, but Austin obviously had some firm basis for. Anyone know if the FN basis engine was so treated? Perhaps it vents air as well as oil. On the upstroke oil must enter. Many remetalled rods have the drillings without the trench, a reasonable compromise. Having read too many books, when remetalled I plugged the holes with screws now immovable. Since done about 20,000 miles but not  above sustained 4,000 rpm.
Reply
#10
Hi Everyone,

I am posting these photos on Keith's behalf as he is not familiar with the process of adding photos.

These show what looks like a Phoenix crank although does ACS engraved on the web point towards Allen Crankshafts.

Cheers

Marcus

       
.jpg   imagejpeg_2.jpg (Size: 104.87 KB / Downloads: 588)
Reply


Forum Jump:


Users browsing this thread: 9 Guest(s)