Thread: Harmonic balancer on 454 has 4 timing marks.....

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Originally Posted by pat mccarthy

this was over 20 years ago when i work at one of the largest fresh water marinas around Brennan.s over a mile of yard with docks . it was not hard to work on five boats a day for just tune ups. this is what i was told ... but why ? ask mecruiser they told use NOT to use them. that was back 20years ago and merc was sick of buying back engines with holes in the pistons ..THEY TOLD US NO MORE PERIOD .they said the dealer would cover it . they wanted fuel checked for Octane and timing set were they wanted it . very well could of been them not wanting some super turner with a wiz bang new at that time. timing lite screwing around ?? they said not to use it on the thunder bolt box and thats was a good enough for me..seen some smart a$$ use a snap on one.i told him not to use it on the engine . boat came back in a week with holes in the pistons ?? was it the light ? .the thunder bolt . had a built in curve . the light would change the curve by the way the timing lite work ? i just know what they told us

Sounds to me like the factory had an aggressive timing curve in the box, and if someone "reset" the base timing it threw in too much advance and things went south. There's simply no way that an inductive lead could "change" anything electronic. Had to be the guy "checking" making changes he did not understand in the earlier days of electronics, and burning up engines. That's how it sounds to me, anyway, but I'm not in any way a boat guy.

Originally Posted by rspears

Sounds to me like the factory had an aggressive timing curve in the box, and if someone "reset" the base timing it threw in too much advance and things went south. There's simply no way that an inductive lead could "change" anything electronic. Had to be the guy "checking" making changes he did not understand in the earlier days of electronics, and burning up engines. That's how it sounds to me, anyway, but I'm not in any way a boat guy.

well i was a boat guy but that was 20 +years ago only job i hated and loved equally.no i did not know how the box worked .i have abit better idea now? not really.way to many things to think of were i used the msd.s marine dist like the auto dist it.s curve can be tuned in has it.s springs and a limit bushing .the thunder bolt was potted no way to move the curve . yes a pick up should not hurt the box and yes i used a induc pickup timing lite every day back then .but thats was not the deal it was the way the timing lite work out the curve out on the timing lite with the dial in lite . like said box.s was some what new and so were the timing lites but mecruiser told use not to use that timing lite on them boxs so as a mecruiser mechanic i was happy to play along,as there was many things get drilled in your head most of the time you walked the mecruiser line . but that was not always the case with me... as for the thunder bolt box. dist/box. i had one in a 396 and my 454 worked very good on the street set the base timing like the many boats and used it . what total timing was? boxs did go by engine hp and rate of curve by part number. traded the two set ups .for two gm HEI built buy accel .to a guy with a offshore cat race boat