Screw size for engine baffles

[FireMedic_2009]

Looking for the screw size n thread that attaches the engine baffles. I believe 12 screws are needed and 3-4 larger screws (behind cyl #3 and #4)
Thanks

 

[Mike S]

1/4 x 20 IIRC.

 

[Freemasm]

Were those course threads and not 1/4-28s? Can look tonight if definitive answer not provided by then.

 

[mburch]

MS35206-281, aka AN515R-416R12, aka 1/4-20 by 3/4" long. Almost everything that threads into a Lycoming cast part is coarse thread.

 

[Mel]

Were those course threads and not 1/4-28s? Can look tonight if definitive answer not provided by then.

Typically course threads are always used in castings such as the cylinder heads and crankcases.

 

[wirejock]

Engine holes for baffles

1/4 x 20 IIRC.

The engine threads are coarse thread.
1/4-20 mostly. A few 5/16.
Buy Grade 8 from the hardware store.

 

[Freemasm]

Typically course threads are always used in castings such as the cylinder heads and crankcases.

Has been a while. At least I don't have to pull the drawings tonight. Should have known better considering the design vintage. Thx.

 

[Marc Bourget]

Why the recommendation to buy Grade 8? Can't be load, is it plating, or??

 

[wirejock]

Grade 8

Why the recommendation to buy Grade 8? Can't be load, is it plating, or??

Not load. Plating and higher quality hardware. The difference in cost is negligible.

 

[Webb]

You may want one of these on the bottom attach bracket on #3.

AN500A-416-12

 

[FireMedic_2009]

Thanks everyone. I appreciate it!

 

[FireMedic_2009]

Where can I find a chart on the MS screws to determine what the numbers mean? MS35206-281 is for 1/4”-20, 281 is the length of 3/4”. So what would the MS number be for a 3/16” dia screw and what would be the thread, 20 or 24.

Thanks

 

[mburch]

Where can I find a chart on the MS screws to determine what the numbers mean? MS35206-281 is for 1/4”-20, 281 is the length of 3/4”. So what would the MS number be for a 3/16” dia screw and what would be the thread, 20 or 24.

The most convenient reference that I consult the most frequently is the Genuine Aircraft Hardware website.