stunthanger.com
Engine basics => Engine set up tips => Topic started by: Fredvon4 on March 02, 2017, 10:50:03 AM
-
So--- I found a New un used version and got myself a Brodak (Tom Dixon I assume) tongue muffler for it.
On this engine the Muffler threaded holes are in the exhaust flanges of the engine
The tongue muff did NOT have through bolts included from Brodak
I have tried:
4-40
4-48
5-40
5-44
and ALL will start for one or two threads but NONE are the right size
The question is ---what size and threads are cut in the bosses?
Should one of these have worked, and I need to just get a tap and chase the threads?
-
blank
-
RE your suggestion for the Fox 40 Muffler bolts... I did not try smaller 3 sizes as I started at 4-40 and they did fit--- but bind in two rotations ---so I figured wrong TPI....I tend to think a 3 x 48 would be terribly loose
MM I tried all my stock of the above listed bolts by finger... drilled or threaded at an angle would not be the issue
Interesting that the 5 X (xx) also started but also I think wrong TPI....
I guess no real big deal as there is plenty enough meat on the engine flanges to decide to use 6x32..drill with proper drill and Bottom tab the holes to the over sized bolts
-
RE your suggestion for the Fox 40 Muffler bolts... I did not try smaller 3 sizes as I started at 4-40 and they did fit--- but bind in two rotations ---so I figured wrong TPI....I tend to think a 3 x 48 would be terribly loose
MM I tried all my stock of the above listed bolts by finger... drilled or threaded at an angle would not be the issue
Interesting that the 5 X (xx) also started but also I think wrong TPI....
I guess no real big deal as there is plenty enough meat on the engine flanges to decide to use 6x32..drill with proper drill and Bottom tab the holes to the over sized bolts
Fred, I've always used 6x32 in all my Fox 40's. Sometimes I have had to just use a tap to clean up the threads a
a bit .
-
Try 6 X 32. I'd go to ACE Hardware and have a try at their assortment!
Phil Spillman
-
RE your suggestion for the Fox 40 Muffler bolts... I did not try smaller 3 sizes as I started at 4-40 and they did fit--- but bind in two rotations ---so I figured wrong TPI....I tend to think a 3 x 48 would be terribly loose
MM I tried all my stock of the above listed bolts by finger... drilled or threaded at an angle would not be the issue
Interesting that the 5 X (xx) also started but also I think wrong TPI....
I guess no real big deal as there is plenty enough meat on the engine flanges to decide to use 6x32..drill with proper drill and Bottom tab the holes to the over sized bolts
That's probably what I would do. All the Fox muffler attachments I have seen have been 4-40's but you really have no idea what they did. It could have been a 4-40 with a worn tap, or even some metric size they happened to have on hand (like 3x.6).
Brett
-
Fred,
I've always used 6/32 sized bolts, in all my the Fox 40's.
sometimes you need to clean up the threads with a 6/32 tap.
-
blank
-
Of all the bolts I tried, the 5-40 felt best so I took a dare:
I tried a 5-40 Starting tap by finger, and it felt right so I went slowly in and out to chase the first two or three threads.... then tried my bolt again and she screwed in to the full length easy but snug
Then I took the tongue muffler to install, and noted the muffler holes were ever so slightly too widely spaced but real close
Assumed some previous attempt to install the muffler caused the engine flange threads to get buggerd a bit
Since the muffler holes are un-threaded I just ran a next step larger drill through one of them to gain a schoche of clearance and slop... done and done...