RPMs wont go above 4k...not overpropped.

[tank1949]

I hear crickets.....

 

[AKJohne]

I hear crickets.....

X 2.... what happened.........?

 

[Railroader12]

Sorry guys, been busy. Update for ya here...

New dizzy came, I decided to send it back after realizing I shouldve just spent a few extra bucks for the Delco EST and scratching my head on how I was going to retain the shift interrupter switch functionality. Still havent purchased that either because the season is coming to an end and I MAY just re-power to the 5.7 in the winter anyway.

It still drives me nuts how smooth it runs but just falls flat on its face at 3800-4k. Swapped props from the 17" SS to the 19" again just to check and didnt gain any speed whatsoever 34mph +/-1 and only lost maybe? 50-100RPM which is not at all correct as we all know, that should cause 400 RPM change.

I did a lot of research in the meantime and came upon a little fun fact while I was at it.....the Denso unit they use for the TBV are essentially street bike ICMs commonly used in Kawasakis, also used in farm buggies and (I chuckled) a big ol' brigs n straton mower motor. Hardly worth the $500 premium merc seems to think they are worth considering they are the only company in existence using them in full size engines it seems. Everyone else sells replacements for $250 Retail brand new and I would swap to one of them If I could get my hands on some timing tables since that seems to be the only difference between them all.

Anyway...Ive got maybe 3 more trips to the lake before I winterize so what I decided to do was temporarily cut the alarm system completely out of the loop and triple check the grounds and see If maybe something there is causing it to not advance. Doesent make much sense the way it acts, its not burnt, does lock into base mode and comes back out of it so its functional in some way. Seems to me they either work, or dont. Ive only found maybe 3 examples of anything similar to what mine is doing and 2 of them were wiring related.

Ill report back when I get to the bottom of it.

 

[Railroader12]

Finally had time to clip the alarm wire, yellow temp sensor wire, and run a new ground just incase. I even swapped to a 15" prop just to see what would happen. Timing still the same, 15" prop did raise the rpm to roughly 4500+ but my speed hasnt changed 1mph up/down from any the 4 props I've tried (21,19,17,15). Also paid close attention to throttle and I get no change of tone, power or RPM from 3/4 to WOT even though the blades definitely hit 90 degrees physically at WOT.

Hopefully I can find a cheap Thunderbolt ICM on ebay over the winter, if not I'll go for the Delco system before I de-winterize it next spring.

 

[achris]

Just for S&Gs... Run a hot wire DIRECTLY from the battery to the coil + and see how it goes. (Be aware you'll only be able to turn the engine off by pulling that wire)

Also check that you have a wire from the distributor body to the engine block. Seen problems with a bad dizzy ground. (yes, I know, it's bolted into the engine block... Doesn't mean it can't go bad. I know! Read HERE)

Chris.......