At least I know for sure what this thing is!
I got this engine in my "as is" Donzi Black Widow 24' purchase a couple weeks ago, and have since taken the heads off to be hot soaked / blasted and have the valves re-seated. One valve was bent, but no obvious damage was done (slight nick on piston head).
I ran the block number as:
10237297...454.......96-up...4-bolt, Vortec 7400", "L-29" Gen.VI
So I'm actually pretty psyched! The Gen 6 Vortech 7400 is a strong engine, with a 4-bolt main and roller cam setup. Plus while the thing "only" made 290hp, it made 440 lb-ft of torque (stock) - so obviously this is going to be different in my setup w/ Holley 800, Torker II manifold, and Stainless Marine manifolds. I'm confused about how Donzi listed this boat as 365hp though - I believe the 290 was for a conservatively tuned EFI system on the Dually pickup trucks and tow trucks, from what I can read about that engine block. Wikipedia data would be generic and under a carb marine application it could have been set up very different.
Other history I've discovered on the engine - it's got .020 pistons in it which I assume means it's been bored .020 over stock. Perhaps this was done when they put the engine in the boat as a reman - since the engine has to be pretty recent. I was told that Donzi put 454s in all of the Ford 460 boats in 1993 as a recall, which would mean I'm a little confused as to how a Gen 6 "96+" engine ended up in the boat - unless the stock 93 454 blew and they put a reman Gen 6 in around late 90's or early 2000s.
Anyways, the machine shop is going to want parts for the heads soon. I have no idea what cam is in the boat, so I think I'm going to play it safe and buy HD springs for the valves. Is there any disadvantage to running HD springs if it's actually a stock cam still?
So I'm going to list parts, and would LOVE it if everyone could chime in on the parts they'd use in this situation. I also need a new t-stat. The housing is "bonded" to the gasket and I have no idea what part number the gasket is since details on the engine / year / application are sketchy. I think I can find the other gaskets though. Any preference on temps to run?
-head gasket
-intake manifold gasket (Edelbrock Torker II)
-waterpump gasket
-valve cover gasket (if I order new "bling" valve covers, will they fit?)
-exhaust manifold gaskets (how do I find the part # for these.. ?)
-carb/intake manifold gasket (do I get this from Edelbrock? - running Holley 800 CFM)
-new tstat
-new spark plugs (TONS of conflicting info on these)
valvetrain:
-new springs
-new valve (guy at machine shop is going to find this he said) others will be re-seated
-new pushrods (I was going to just run the generic GM Performance set, like $63)
-new lifters (I was thinking it was a flat tappet motor - no marks on cam for cyl. that bent valve - should I reuse since they're roller lifters?)
-alum. roller rockers
-stud adapter set for vortec heads
-probably new belts while I'm here, the serpentine system is totally custom so I'll have to follow the existing #s)
Any other thoughts? And please resist the urge to suggest that I should rip out the motor and replace it with a $15k ZZ502 or full rebuild. Yes, that would be nice - and if the boat wasn't a 22 year old "oddball" I might consider that, but I'll probably keep it for a year and move up to a slightly smaller ZX - for now considering we skipped spring and it's 75 deg out, I'd like to get the thing on the water and enjoy my first Donzi
Before and after - well, no "after" for the heads yet - but still. Our consensus is that he let the motor sit and rust w/o fogging it, started it up and ran the $hit out of it, valve guide grabbed and valve bent - maybe water got through there somehow or the rest of the water is from condensation (there was visible condensation forming on rockers when I took off the valve covers) I cranked the engine for a long time checking cyl compression and such, so it might have mixed. Oil on dip stick is pristine. Note valve contact in 2nd pic, have been told it's cosmetic and to throw the thing back together.
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