1979 400 motor question- Help me!

[Droobie]

Hi guys, hoping someone can shed a little light on a problem I am having on my current restoration.  On the right (sprocket) side of the engine, just behind the countershaft sprocket, is a curious bolt that held on a combination chain rub block/spacer. The bolt it roughly 1.25" long, and seems to have tapered(pipe) threads. It is hollow at the end, and has notches cut in an "X" about half way towards the head. My dillemma is that at one time, said bolt on my engine must have worked itself loose, and while it was sticking out, it suffered quite a hit, one hard enough to elongate its hole in the magnesium cases. What does this bolt do? Why are the notches there? Is it important? Can i just plug the hole up with a helicoil and a regular bolt? Help me!

[Droobie]

PLEASE E-MAIL ME WITH ANY INFO!   [email protected]  THANK YOU!

[DKWRACER]

Just aft of the counter shaft is the rear engine mounting bolt which spans the width of the engine....where the mounting bolt comes thru the throttle side of the engine case would have been a special spacer which is captured by the rear engine bolt and also held in place with a small additional bolt approx 1.5 in. in length, this block served two purposes, keeps the engine spaced properly at the rear mount, and in some cases, held a chain tensioner roller on two forks..Some of the bolts, were bolts (retro'd), most often it is or was a stud, with a tapered looking  allen head cap fastener.....I sure hope this is the mystery bolt you are seeking info on......

[Kip Kern]

Droobie   If the chain rub block/spacer is made of steel and the bolt you are talking about is a 10mm, then it is the bolt that holds the spacer to the engine case.  Normally, it is a stud that threads into the case side and the spacer cradles it until a special 12mm hex head cap nut and spring/lock washer is threaded on to hold the spacer down.  If this is the bolt we are talking about, the only important thing is that the stud/bolt used to hold the spacer on the cases does not thread "into" the right case half as it would hit something inside the engine that rotates.  Hope this helps.

[DKWRACER]

Rust never sleeps, thanks for the followup.....Tom

[Droobie]

ok guys, this all sounds very good. you kno, your describing the bolt as an allen-hed type, whereas the one on my motor is a 17mm hex, which leads me to think that it is not the correct bolt. if all it does is hold the spacer to the frame, then good, i can fix that relaly good with either a tap( messy, require cleaning shavings out of motor) or some JB-Weld (my prefered methond of putting the boly solidly back into its home) thank you for your help!

[Rocket]

Droobie
If I understand your question, the bolt you are referring to is actually a 10mm x 40mm stud.  this threads into the case and then either a 10mm hex nut or socket allen nut holds the motor mount spacer in place.  I believe the socket allen nut is either a 12mm or 14mm allen wrench size.
Rocket