5 yrs ago I would have said...it's clumsy but quite manageable. 4 yrs ago I popped a hernia on a RV tire of all things.
Bravado has left the building so to speak.
Be inquisitive, start a 4 degrees and work the timing up slowly until the "marbles" start. That is detonation and you engine will not withstand that. Timing and carberation go hand in hand. Because your advanced timing cured a bog I highly suspect you have a carb problem.
The timing setting...
Finding a baseline for your engine should be quite simple or...can...be would be better said.
Per Mr Danforth posted spec set your static timing to 4 degrees.
Next stop unhook your throttle linkage and adjust your idle down to 650/700 rpm. By now you should be aware of the idle speed screw...
The fact it turns up the rpm is good, those marble sounds are bad. Mr. Danforth is correct stop right there.
But I will ask just out of curiosity what size prop is on that boat along with weight and length...prop and boat description.
it is odd advancing timing cuts the bog..running very lean?
Perhaps a more complete guide towards using a compression test.
https://www.freeasestudyguides.com/compression-test-injecting-oil.html#:~:text=If%20a%20cylinder%20has%20low,the%20compression%20gauge%20back%20in.
Your over thinking here. Make sure your drawing vacuum from the intake not the carb. Make sure all the vacuum ports are freshly plugged..aka no leaks.
Still bad low readings, dump a few cans of seafoam down the carb, let the thing soak under high heat. Yes snake oil clears up sticky vales...
That cylinder pressure would get a compression ratio of about 10.5 something. Meaning you would be using a engine that has been hotroded a smidge, also known as slightly tinkered.
More than probably your harmonic balancer has slipped, 2 degrees base timing is pathetic for a 454 vortec.
Or the balancer was misaligned on this new engine..Or the distributor installation?
Rich mixtures requires less timing
Lean mixtures require more timing.
This is all about flame...
What yr is this 454? Do you know the advance curve your new distributor has?
10 initial plus 24 degrees provided by the dist would be a total of 34 degrees.
454 engines are quite comfortable with 36 degrees total, they are different than small blocks.
Setting a timing curve is merely one part...
You need to get that fuel pressures checked, orileys or auto zone rents the fuel pressures tools and fittings. Been there done that. One gas line/tank for both engines?
This engine is very old, take a neon/led light and illuminate your injectors at low idle and up...
The below site will help you thru this, perhaps one of best minds still in the business. They may well want your carb number.
https://cliffshighperformance.com/
Call us at 740-397-2921 if you don’t see what you are looking for..
We carry every Quadrajet part currently available and we'll build...
Timing advance seems to be a very touchy subject most of the time, opinion oriented. Boats can be quite unique, they have a built in dyno..opinion of course yet any tune you do will become very apparent...you will have instant results right in front of you.
Over the yrs I've always used a...
Watching this thread is interesting, if your going to install a flat tappet you need your ducks in a row.
More than probably a lot more would be in order, a compete setup, one with springs,keepers cam ect ect.
Spring pressure not to exceed 100 lbs.
New flat tappet cams fail at alarming rates...
You've just completed a well done repair, take some time to breathe. And a first for me a oil recommendation, Rotella t4 t6 5/40, marvelous stuff it actually has detergents that will cleanup deposits in old engines. And yes it is diesel oil rated for gas engines as well.
Then there is the...
