P

PIN 37

Well Known Member
Can anybody tell me where I can get course thread bolts as used on Lycoming
engines. I cant find them in the spruce catalogue. I want to get some drilled head bolts to bolt my crank sensor on my engine. (not supplied with the Plasma III kit):confused:
 
Lycoming P/No's

Phil,
Don't know of a source, other than your local GA/Piper/Cessna parts supplier. I know that the Piper sales company close to me stocks all the Lycoming parts.

In case it helps, here are the Lycoming part numbers for all the types of bolts I spotted in my Lycoming IO-360-M1B Parts Catalog

Lyc P/No = Description

LW-25-0.50 = BOLT-1/4-20 X 1/2 Long Hex

LW-25-0.94 = BOLT-1/4 -20 X .94 Long Hex
LW-25-1.00 = BOLT-1/4 -20 X 1.00 Long Hex
LW-25-1.13 = BOLT-1/4-20 X 1-1/8 Long Hex

LW-25-1.25 = BOLT-1/4-20 X 1-1/4 Long Hex
LW-25-1.44 = BOLT-1/4 -20 X 1.44 Long Hex
LW-25S1.50 = BOLT-1/4-20 X 1-1/2 Long Drive End
LW-25-1.75 = BOLT-1/4-20 X 1-3/4 Long Hex

LW-31-0.94 = BOLT-5/16 -18 X 15/16 Long Hex
STD-2246 = Bolt-5/16-24 X 1.00 Long

LW-31H0.88 = BOLT-5/16-18 X 7/8 Long Hex Drive
 
Loctite???

OK, now you have me thinking. I only used red Loctite. Is that maybe not enough? This considering I have a dual LS setup and everything rests on those bolts staying in place.
 
You can get good quality grade 8 bolts that are superior to grade 5's that Lycoming specs from Tractor Supply. Worth noting is that Continental uses AN bolts all over their engines so there's nothing wrong with going that route either. In any case the through bolts provide the critical strength of an engine so any other bolts like the case half bolts merely keep the thing from leaking oil.
 
Corbinace, I too have duel LS, and I think it would be somewhat disappointing to have the engine stop in flight due to the sensor bolts coming loose, hence why I want to safety wire the sensor mount.

These aircraft grade bolts are very difficult to get here in Australia. I still dont know if there is such a thing as a 1/4 x 1/2 UNC drilled head bolt.(aircraft grade), much less where to get them. The places suggested so far dont ship to Australia in any case. (Spruce does ofcourse):(
 
If you must have aircraft grade and drilled heads, you're looking for MS20074 bolts:

http://www.gen-aircraft-hardware.com/images/pdf/ms20073_74.pdf

However, an SAE UNC is more than adequate for attaching the crank sensor plate. Drill the heads yourself. A 1/4-20 grade 5 is good for about 3500 lbs and you have four of them to hold the plate. In any case, the install is mostly governed by the quality of the threads you hand tap into the aluminum nose case.
 
Last edited:
If you can take an...

PIN 37 said:
......
These aircraft grade bolts are very difficult to get here in Australia. I still dont know if there is such a thing as a 1/4 x 1/2 UNC drilled head bolt.(aircraft grade), much less where to get them. The places suggested so far dont ship to Australia in any case. (Spruce does ofcourse):(
Click to expand...

...extra 1/8 inch, then ECI certainly lists one....

http://www.eci.aero/exp/products_detail.aspx?in=74

Three Australian suppliers are listed.
 
Last edited:
Thanks for that Gill, I'm obviously not real good at searching, but I am improving. Will get the parts today Thanks:)
 
rocketbob said:
You can get good quality grade 8 bolts that are superior to grade 5's that Lycoming specs from Tractor Supply. Worth noting is that Continental uses AN bolts all over their engines so there's nothing wrong with going that route either. In any case the through bolts provide the critical strength of an engine so any other bolts like the case half bolts merely keep the thing from leaking oil.
Click to expand...
Would a standard AN bolt with a lock-nut be OK, then, to use on the oil sump? I'm adding a stand-off for wiring purposes but need a longer-than-original bolt as a consequence. I'd use a course thread bolt but it appears that they would be way more expensive, especially if shipping is included.
 
You must log in or register to reply here.