bolt and nut size questions

[Bubblehead]

I am changing intake pipes and exhaust manifolds on my IO-360 parallel valve RV-8. The long story about why is posted here: URL="http://www.vansairforce.com/community/showthread.php?t=31370"]http://www.vansairforce.com/community/showthread.php?t=31370[/url]

One intake bolt has some thread damage and the nuts and lock washers on the exhaust studs are rusted up a bit.

Four questions:
1) What size nuts go on the exhaust studs? - found this: 5/16" - 18
2) Are the lock washers special steel because of the high temperature?
3) What AN or MS or other spec bolt is used on the intake pipe?
4) what is a good source for 1, 2 and 3 above.

Thanks,

John

[mahlon_r]

Lock washers are just standard plain cad plated star washers. Lycoming P/N STD-475
Intake bolt is 1/4-20 X 1.25 long. Lycoming p/n is STD 1215. I would think any grade 5 or 8 1/4-20 course threaded bolt of the correct length would do.
Exhaust nut is P/N STD 1410.
Any Lycoming distributor or any aircraft engine parts supplier should have all of the above.
Good luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."

[caryr]

if u are going to replace the nuts

ACS has the nuts for this.

A normal 1/4-20 thread would use a 7/16 wrench. ACS has nuts a little beefier that takes a 1/2 wrench. There's probably a more accurate description for this, but its in my language.

I just use new star washers.

[Bubblehead]

Mahlon_r and caryr - you guys have shared a lot of info to help me get things right. Thanks. I will order parts tonight.

Thanks!

[Bubblehead]

I was able to get the right bolts, studs, nuts and washers from JA Air Center in West Chicago, IL/DPA. Doug there was very helpful. They've also sold me brake fluid and other miscellaneous parts.

One of the threaded holes in the cylinder for the intake pipes has slightly damaged threads. I'll pick up a tap and tapping fluid tomorrow and clean up the threads. Then I should be able to bolt up the intake pipes, new 4 into 1 exhaust with heat muff and maybe be back flying Saturday or Sunday. I'm working some long hours and commuting over 1 hour each way each day so I don't have too much energy at night but should be ready to hit it Saturday morning.