Topic: 1/4" rocker stand bolts uggh.

[Don R]

 I was all set to put 8 long heli-coils in my big port, big valve, RC Eng. head. Alas, the 1/4" holes have coarse thread heli-coils in them already. Fudge, but I didn't say fudge. I'm not finding the old 1/4" bolts either so now I'm leaning towards trying 1/4" studs.
 Other ideas?

[BenelliSEI]

I'd prefer studs. Loctite them in once and hope for the best. Anyone make a high quality stud with a UNF top portion?

[Don R]

 They do, most are 1/4" coarse on the bottom and fine on the top side. I had some stainless bolts the correct lengths, I cut 4 of them and was able to thread them in. the jury is still out on whether I like it enough to leave them in.
 This head has an Engle J cam, it's pretty big, other choices would be a Kenny Harmon F or an RC315. I'm wondering if the ports are excessively big, on his 1124 stroker motor the PO said he ran within .02 of the NHRA record way back when. The tech guy asked him to keep it in mind if he would be willing to do a teardown in case he broke it. I'm thinking 997cc using his old head, header and frame.
 Everything needs to be painted black for a good tribute bike. Gone but not forgotten.

[MRieck]

Don, Don, Don.....you have been old schooled. The next build will be perfect.😉👍

[Don R]

 True story Mike.

[Don R]

 Stamped RC engineering. Like the 3 bears, too little, too big or juust right?

[Tracksnblades1]

Stamped RC engineering. Like the 3 bears, too little, too big or juust right?

I like the stud idea. That was a day dream of mine that someone already made a reality..
I would blue lock tight them finger snug then set the towers on empty and torque them down
so they’re straight up against the threads while the loctite cures.. Seen bad results torquing studs down
against their treads or blind hole bottom..Ends up having to drill holes out just to get the heads or caps on afterwards, it better to have them all pulled straight up perpendicular to what their holding down..learnt that building a 496 before they were cool..couldn’t even get the Big Brodies to go down until we installed the studs this way…or drill brand new heads….😳

It looks pretty smooth on an IPad..Did they weld the spigot in..?
That was the practice back then…😇

[BenelliSEI]

+1 for studs. I always shudder when I see headers screwed into the head with cap screws or bolts. Blue loctite on the buried end and snug them up lightly…..

[Don R]

 There was one bolt that tightened hard when I tested them, I have the feeling it wasn't tapped perfectly. I was going to use the cam towers with a 1/4" drill blank to line the drill press up after squaring up the table when I thought I could heli-coil back to 6mm. I even found the longer Honda 6m bolts.

[Don R]

 I'm thinking these early rocker shafts need to be allowed to rotate, the 1/4" bolts are binding them up. I think Hondaman mentions that there might be some reduction in friction. The 836 that I built has the shafts spinning and the oil holes drilled. I rode that bike and the Rat Race 836 back-to-back today, I think my build pulls harder down low 20-40 mph even with the too big KH F cam. Both are ported, both big cams, mine has less compression than the RC motor.
  I wish my race cars data recorder was more portable, I'd love to compare those two bikes with more than the seat of my pants.
 
 

[willbird]

+1 for studs. I always shudder when I see headers screwed into the head with cap screws or bolts. Blue loctite on the buried end and snug them up lightly…..

I was kind of born with an allen wrench in my right hand LOL but I never really had an issue with my 1972K2 CB750K and allen bolts holding on the MAC header I bought about 1992. In general I do prefer studs to bolts though.

Bill