The big end bolts on the Speedy engine in my Nippy are rather different from standard bolts - see pictures
The pin which locates in a slot in the big end casting ensures that the bolt cannot turn and the chamfered side of the bolt head always faces outwards and clears the crankcase and/or the cam shaft.
The two bolts in the photo are old ones. They have more massive heads and pins than the newer ones
Does anyone know whether new bolts like this are still available?
Not a great design of bolt having a hole drilled for the pin at the corner (already big stress raiser.) Surely nothing wrong with standard bolt registering on the flat of the head against conrod.
(02-03-2018, 01:33 PM)Dave Wortley Wrote: Not a great design of bolt having a hole drilled for the pin at the corner (already big stress raiser.) Surely nothing wrong with standard bolt registering on the flat of the head against conrod.
Dave, exactly my thoughts.On a Speedy/Nippy Conrod there is no "flat" hence the pin under the head.
12/4 Conrods use the same design but at 3/8" Dia.
Steve,Would capheads with all metal locking nuts be acceptable?
Or you could use Austin 10 bolts which are 5/16 dia but longer than standard seven bolts, they have a locating flat like a seven, no pin.Instead of drilling the pin hole at right angle to the length you could drill through the top of the head.
Sure fire solution would be Phoenix crank and rods, and peace of mind if you have a proper speedy crankcase, wouldn't want break one of those
I agree that drilling the bolt to accomodate the pin is questionable but I assume the engineers who designed it that way left enough reserve to take the stresses.
Capheads, and I assume you mean those with sockets, would hold the big ends together OK but the essential feature of the present bolts is the chamfer which allows the bolt head to pass the camshaft without touching. They are extremely close! On no account may the bolt turn and then foul the camshaft. That's what the pin is for.
Using Austin 10 bolts, as you suggest, is an interesting idea and would imply grinding off the chamfer but I doubt that there would then be enough material left in the bolt head to subsequently hold the vertical pin. A solution could be to cut a slot in the head, fit a steel tongue (would brazing hold it?) which protrudes below the head and finally grind the chanfer.
Phoenix crank and rods would be the ultimate solution and I assume the big end dimensions would allow more clearance in the crankcase for them and their bolts to pass the camshaft. Yes, it is a proper Speedy crankcase. A crack in it was repaired by metal stitching about 10 years ago.
At the moment I have enough of these big end bolts but if new ones were available, (as they were about 40 years ago!) I would be interested in having a few in reserve.
Steve, when i rebuilt my Speedy engine I fitted Phoenix Crank and rods to protect the crankcase, so yes they fit and I found no problems other than not being entirely happy with the Phoenix starter dog. As supplied the oil ways in the dog are on the small side and in the wrong place.
(03-03-2018, 06:54 PM)Ian Williams Wrote: Steve, when i rebuilt my Speedy engine I fitted Phoenix Crank and rods to protect the crankcase, so yes they fit and I found no problems other than not being entirely happy with the Phoenix starter dog. As supplied the oil ways in the dog are on the small side and in the wrong place.
Ian, is the starter dog the bit that the starting handle engages into? A new one would not be amiss since mine is rather worn and the starting handle tends to jump out.
Did you modify the oil ways. If so, what did you change?
As you see, I'm toying with the idea of going to Phoenix crank and rods.
What other surprises can I expect?
I've just had the block re-sleeved for new slipper pistons.
Just FYI if you are thinking of new gear, I replaced the con rods and not the crank on my speedy engine. With the cost and hassle of getting the rods white metaled due to the different journal width between the original and the Phoenix rods I probably should have replaced both at the same time.
I found no problems or surprises other than the starter dog, my car uses the original 3/8" lift cam and everything cleared when assembled. The issues were the that oil ways within the dog were too small for my liking and the cross drilling was in the wrong place, the dog is hardened so a drill bit with tungsten carbide tip is required to open the holes out. Probably with hindsight, had I been aware of this when I ordered Phoenix could have made the starter dog to suit my engine. I believe the issue stems from the fact most pressure fed cranks are built into non original engines using a completely different oil bottle and seal arrangement at the front of the engine.
(03-03-2018, 06:54 PM)Ian Williams Wrote: Steve, when i rebuilt my Speedy engine I fitted Phoenix Crank and rods to protect the crankcase, so yes they fit and I found no problems other than not being entirely happy with the Phoenix starter dog. As supplied the oil ways in the dog are on the small side and in the wrong place.
Ian, is the starter dog the bit that the starting handle engages into? A new one would not be amiss since mine is rather worn and the starting handle tends to jump out.
Did you modify the oil ways. If so, what did you change?
As you see, I'm toying with the idea of going to Phoenix crank and rods.
What other surprises can I expect?
I've just had the block re-sleeved for new slipper pistons.
(04-03-2018, 08:42 PM)Ian Williams Wrote: I found no problems or surprises other than the starter dog, my car uses the original 3/8" lift cam and everything cleared when assembled. The issues were the that oil ways within the dog were too small for my liking and the cross drilling was in the wrong place, the dog is hardened so a drill bit with tungsten carbide tip is required to open the holes out. Probably with hindsight, had I been aware of this when I ordered Phoenix could have made the starter dog to suit my engine. I believe the issue stems from the fact most pressure fed cranks are built into non original engines using a completely different oil bottle and seal arrangement at the front of the engine.
Ian, I have been in touch with Marc Taylor of Phoenix Crankshafts and he very kindly sent me a drawing of the starter dog that they make based on a 30 year old design they received from an A7 owner, Brian King (are you out there anywhere Brian?). On this drawing the cross hole for crankshaft lubrication is positioned 13/16" from the external face of the 1 1/2" AF nut whereas on my starter dog the cross hole is 1 1/8" from the face of the nut. I guess this is the same problem that you faced. The diameter of the hole is 3/16" as on the drawing.
Marc says it would be possible to relocate the cross hole to fit.
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