In theory what would have to be done to make the 140 turn rpms like a 3.0 with less timing?
I am assuming when you say valve timing there are cam differences. what differences are there in terms of fueling?
Replaced the u joints and I am happy to report I am noise free. I'll start playing with timing again to see where the limit is at idle to get 30-32* up top and hopefully see full rpms again.
I can %100 confirm that setting base timing at 1* results in a rpm limit of 3600 rpm. 8* base timing...
Well to update more, I am happy to report that the noise I was hearing was not in fact timing knock, it was the u joint wearing out. went up river today fishing and it lost power to the prop. The marble sound I heard was a bad ujoint, which now that I think about it is the right sound for...
sad but true, :ROFLMAO:. I've been telling the wife we deserve a new boat. However she tells me " it's not as fast as it used to be" is not a good enough reason.
I set timing back to 8* and I will spend some more time looking for the issue as I can. The boat is just an "upstream boat" anyways...
Its not a normal 3.0 noise, it's not a good noise I am just not sure it is knock. It almost has a harmonic rattle as if something is loose and shakes at a specific RPM.
Dunno I am gonna check more or blow something up looking for it.
Well I am not convinced it is detonation for a couple reasons, or at least detonation due to timing. I made a mistake earlier, i had timing set at 8* base not 12*
1. setting timing at 8 vs 4 vs 1 vs -1 makes zero difference on the noise and what rpm it happens.
2. doesn't matter load or no...
If I set my static timing to 4* my total timing ends up being ~28*, and my max rpms are ~3600-3700 rpm, which makes sense when I look at the spec on timing for a below 0C856558 serial number motor. The boat runs fine just doesn't have any top end.
What I really would like to know is why...
From Post #10
https://forums.iboats.com/threads/mercruiser-140-points-to-delco-est-results-in-low-rpm-at-wot.754588/post-5749825
Is the above not correct for my serial number engine?
I am not arguing about the marble sound and it being bad, just trying to sort out conflicting information...
Total timing that old 140's want is much higher than 3.0's. The book calls for 36* up top vs 24* for a 3.0
The est ignition doesn't have enough advance to get the total timing the engine wants up top.
It's been awhile, but I wanted to update this just in case someone else has the same issue. I have base timing set to ~12* and I am now able to rev out to ~4100 rpms which is much better than it was last year. I do have a strange marble like noise at a specific lower rpm that I need to check...
Got ya.
Well I got it all wired up and then the starter started making a terrible noise and the key stopped cranking so I threw in the towel for the day.
Thanks again. I'll report how it runs when I get it back in the water.
