Looper head studs

**Captain75** · 01-10-2018, 08:00 AM

Hello!
Is there someone on this board who can help me find 5/16 UNC/UNF for my Looper build? I have searched for a very long time with no luck

. I want to be able to read the piston tops without risking the threads.

Best regards!
Anders

**ThatguyDave** · 01-10-2018, 12:19 PM

I'd try McMaster Carr. They're my go to for most hardware in my machine shop. Prenominal website. Good luck

**patchesII** · 01-10-2018, 01:45 PM

I'd call or email ARP. I bet they have what you need if you just gave them the lengths of threads and total length

**phillnjack** · 01-10-2018, 07:17 PM

why not just go to car exhaust centre and get the studs ? they are common over here .
infact about the most common size for manifolds, and you can get stainless or steel or even brass, plus brass or copper nuts and washers too.
also a lot of carb inlet manifolds have them too .

just an idea

**BarryStrawn** · 01-10-2018, 08:52 PM

I've made quite a few studs for outboards because I never found anything off the shelf with a good fit. The auto stuff may work good enough if you are happy with maybe 5/8" of thread engaged. Which is probably OK but the stock bolts go deeper than that.

For a looper I use ARP stainless bolts with 5/16"-18 threads and 2.75" or longer. Cut the heads off and thread 5/16-24 with a Geometric die head on the lathe. I would roll them if I could find a decent Fette head for reasonable money. Any decent machine shop can do this.

These will have over an inch of thread and some blocks you may need to run a bottoming tap down the hole to get full thread engagement. I think it is worth the effort.

**phillnjack** · 01-10-2018, 09:39 PM

How long are the threads going into most outboard blocks ?

**H2OPERF** · 01-11-2018, 10:16 AM

I had the same problem, worst thing is the standards for thread length tells u that you only need 1.5 to 1 3/4 the diameter of the fastener for sufficient thread engagement ... May be fine for steel but I call this BS for cast aluminum.. yes if all is perfect no corr, stud put in from day one.. tight threads ect.. So most off the shelf fine/coarse studs have very short coasrse thread lengths. OMC blocks have just under an inch of threads as i think Barry said so finding studs with the longer coarse thread is near impossible, most off the shelf studs i found in the length needed are for car carb spacers and only have about 1/2in of coarse threads if ur lucky. Next problem is there are 40 of them so if you want to use something fairly strong (more expensive) chromolly 8740 or better yet one of the really high strength nickel alloys a286 or inconel if ur running in salt and dont want rusty studs now it gets really expensive with nuts and all.. A cheaper option may be to buy good threaded rod.. cut out 40 and just use coarse nuts this still saves the block threads from bolt removal cycles..Rolled threads are best if you have the choice. Dave

**H2OPERF** · 01-11-2018, 12:19 PM

The one on top is an inconel stud i found from a nascar team made by a1 technologies rolled threads perfect but unfortunately not in business any more, i was told they were a shoot off from sps who make nearly all the aerospace fasteners for boeing,grumman, nasa etc but for some reason droped the line that made stuff for racing and the public...I have hunted for extras but no luck..the other is a carb stud i got from ebay have no idea what its made from it is cad plated and i have 40 if ur interested in trying them.. the coarse is about .650 and there 3 in long..Dave

**spybot** · 01-11-2018, 01:20 PM

Have a look here for the thread length
https://www.boltdepot.com/fastener-i...ad-Length.aspx
Maybe give you something to go on.
I can give you the name of a place in the uk that ships to The Netherlands ect

**Captain75** · 01-11-2018, 03:32 PM

Is it possible to use these despite their lack of waist?

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**H2OPERF** · 01-11-2018, 04:46 PM

Do they list the tensile strength in KSI, 304 is usually fairly soft, head bolts should be at least 130ksi or better. I don't know about the older loopers but in the newer engines the bolts are 17-4 which are around 140ksi around same as grade 8 steel .

**spybot** · 01-11-2018, 06:15 PM

think you should consider 316 over 304
316 will stand up to the salt water a lot better
http://www.reliance-foundry.com/blog...ess-steel#gref
Andy

**powerabout** · 01-11-2018, 06:49 PM

how about go up to 3/8

**H2OPERF** · 01-11-2018, 10:09 PM

Just my opinion but probably Better off spending the money on higher quality/strength fastener material than drilling and taping the block, to do it right it would have to be all done by a mill to be square and have good threads. The g2 does have larger bolts on the inner rows..