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Originally Posted by 1986Scarab1
(Post 4644864)
Hi All,
I'm not sure what to do here. A month ago I grenaded a motor I put together (backyard build) and it sucks. You can read the saga here - https://www.offshoreonly.com/forums/...new-build.html Based on what I learned from all of your feedback on that thread, I'm sure that I did my "new" motor no favors which probably led to its early demise. It didn't even make it one full season... Long story short, I plopped vortec heads, comp xtreme marine cam, vortec intake, on a rebuilt Mercruiser 260HP block (non-roller). Block had new pistons, bearings, and rods (all factory cast parts). I ordered a relatively cheap rebuild kit (maybe cheap chinese parts? not sure...) for the bottom end at the time due to ignorance on parts. I want to put a reliable, powerful motor back in the boat but don't want to make any mistakes this time. I'm wondering if the cast pistons are just not up to the abuse of my right hand and the bigger cam/heads and stress they put on the motor. Or if the cast parts are just fine and I just never tuned the motor properly? I can get a vortec longblock pretty inexpensive, get the same cam and spring kit (except for roller motor), plop on my intake and have the same power (which was sufficient for me, I gained 9mph!!) and be back on the water pretty quick for pretty cheap. My question is, will it last if I get it tuned properly this time? I've been told that I should go to a forged bottom end, is that true? The cost difference is VERY significant stepping up to a forged rotating assembly. I'm not opposed to doing it if that's the only way i can get the power I'm looking for and have it last.. Just wondering if a factory vortec roller block can take the added abuse of a larger cam and be reliable if tuned properly. The engine I just grenaded was a non-roller, early SBC 5.7 and this is the second time I've toasted it. The first go round, summer 2017, I put vortec heads and intake (factory cam) on the stock bottom end rotating assembly (7 seasons on that motor) and it blew up towards the end of the season. That's when I bought the cheap rebuild kit, tore it down and replaced parts, put new vortec heads on, and added the xtreme marine 12-236-3 kit which made it through 4th of July week. Looking forward to your expertise and feedback, thank you! Heath |
I wouldn't run that Summit street engine in a boat without reworking the heads......jmo
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Originally Posted by Paxtonspeed
(Post 4644995)
The stock 350 long block that Mercruiser used is a car engine. The water pump, starter, alternator, TBI or Carb....etc everything on the outside of the engine are what makes it a marine engine. I think the oil pan may also be different.
The intake you have is fine, I have the Edelbrock version of it on my 383. I thought quadrajets required a special flange to mount, yours looks like the Holley style square flange? You could stick a Holley Marine carb on it. https://www.summitracing.com/parts/h...2670/overview/ These are the cam specs in that motor Cam Type: Roller .495/.503 lift 220/224 duration @ .050, 110 degrees LSA Using 1.5 rockers Are you using the stock manifolds? Through hull or out the drive? My cam is bigger than that, and as far as I can tell, I am not reverting water. Stock manifolds, exhaust running out the side of the boat. Boat has not been on the water, since my cam swap. Running in the driveway on the hose, I have no reversion. I am also EFI, which I think plays into that some, since some tuning with the EFI can calm the cam down at idle. |
Originally Posted by F-2 Speedy
(Post 4645012)
I wouldn't run that Summit street engine in a boat without reworking the heads......jmo
I've heard this before, I'm assuming it's because of the valves correct? Are they supposed to be a different material for marine use since the load is much more? What am I looking at here to do this right? Thanks! |
Originally Posted by BenPerfected
(Post 4645003)
Are you looking for a competent engine builder? It could save you $ I have looked at that route but only went to once builder, Lamar Walden here in Atlanta is the best guy in town. That shop wanted WAY more than I'm looking to spend to do this job. $5,500 for a vortec 355 with forged pistons.. Now that I'm under the impression I don't need forged internals to be reliable I'd love to save the extra money and spend it on the interior instead.. What do you think would be fair to have a builder put it together? |
I have not been as active on the forum as I used to be so I'm chiming in a little late.
A good group of us probably 7-8 years ago or so were really running some good numbers with small boats. Scarab's, Challenger's, Velocity's, Donzi's, Chris Crafts, Sea Rays... some had some fast, I mean, really fast, boats! A lot of us were in the upper 70's and over, and there was a good amount of small block knowledge being posted. Those were some fun days! If I were you, I would pony up the cash to do this: GM part number 12681432, new Vortec 350 long block at about $1900 bucks. Replace the camshaft with a GM LT4 "Hot" camshaft at about $250. Replace the valve springs and retainers with factory GM/Chevrolet LS6 Z06 "yellow" beehive springs. The rest of the valvetrain will be good as-is. Use your existing parts (Thunderbolt ignition, intake manifold, water pump and accessories), and a stock 750 Holley marine carb. Set the all-in timing at 32 degrees. You'll make 375-390 horsepower with the factory exhaust. If the bottom of the boat is good, using a 1.50 drive ratio (which the boat should have) and your 21P prop should get you well into the 60's; any day, every day. It will sound good, and will run like a sewing machine. I had a mishap with a 385 that I built (valvetrain,broken valve and pistons); the above is basically what I put together on the fly, and had back in the boat, running, in a couple of weekends (mine was used/refreshed from Craigslist for a whole whopping $900 plus the cost of the springs, retainers and gaskets). I would not get into having someone build something for you, not at this level. The factory short block is that good as-is. |
Originally Posted by TomZ
(Post 4645937)
A good group of us probably 7-8 years ago or so were really running some good numbers with small boats. Scarab's, Challenger's, Velocity's, Donzi's, Chris Crafts, Sea Rays... some had some fast, I mean, really fast, boats! A lot of us were in the upper 70's and over, and there was a good amount of small block knowledge being posted. Those were some fun days!
This was the last update of the list years ago: Last edited by cfm; 08-07-2011 at 10:43 AM. ===============The List=============== CB-BLR - 1995 22 ft Eliminator Extreme - Click Here - 548cid/ Bravo - 91.7 GPS =========================================== ITLLFLI - 1994 Donzi 22 Classic - Click Here - 540cid/Bravo - 90.0 GPS tdaddy185xlt - 1989 powerplay 185XLT - Click Here - sbc/AlphaSS - 87.2 GPS The Nerd - 22 Advantage Citation - Click Here - Whipple502/Bravo - 87 GPS wtfo - 18' Checkmate - Click Here Built 383/Alpha - 86 GPS CC - 2005 Donzi 22 Classic - Click Here - 525EFI / Bravo - 85.8 GPS Boatally Insane - 23 Checkmate -Click Here Built 516BBC/Bravo 85.4 GPS Nstylx - 86 22 Velocity - Click Here - 406sbc /Alpha - 85.1 GPS Kidnova - 23 Wellcraft Nova - Click Here - Humble BBC/Bravo - 83.1 GPS Run_em_Hard - 1989 Advantage 22' Citation - Click Here - 509SC - 82 GPS jvcobra - 1987 22' Donzi Classic SC'd 454 - Click Here - 81.7 GPS Mudball - 22ft Donzi ZX - Click Here - HP500/Bravo - 81 GPS Ryan00TJ -1984 Hammond Challenger MKII V2150 - Click Here - 385cid sbc/AlphaSS- 80.5 GPS Nauti Kitty - 1979 Donzi 16 Ski Sporter - Click Here - 383Sbc/Alpha SS - 80.3 GPS boatnutt - 22 Eliminator Eagle XP - Click Here - 540BBC / Bravo - 80.2GPS Madpoodle - 1980 Donzi Criterion SS -Click Here - 80 GPS =========================================== persuader - 1995 Checkmate Persuader 235 - Click Here - built 496/Bravo - 79.7 GPS quick22 - 22 Pachanga - Click Here - built 502 / Bravo1 - 79.6 GPS 1000 Islands Donzi - 2002 22 Classic -Click Here And Here - 496HO/2"Imco Shorty -79 GPS Chromegorilla - 2005 Donzi 22 Classic - Click Here - 496HO/Bravo - 77.9 GPS TomZ - Chris Craft Stinger - Click Here - 383sbc / Alpha - 77.2 GPS DonziGreg - 1993 Donzi Classic 22 - Click Here - 76.6 GPS slapshot - Checkmate 229 Maxxum - Click Here - 502/500HP/Bravo - 76 on radar Madpoodle - 1974 Donzi X-18 - Click Here - SBC, TRS - 76 GPS Muddytoy - 1999 Baja Hammer Click Here - Mod'd 454MPI / Bravo - 75.6 GPS ACrooks69 - 1991 Searay 185 - Click Here - 383sbc/Alpha SS - 75.4 GPS Plumcrazy - 1988 Baja Sunsport 196 - Click Here - 383/Alpha SS - 74.6 GPS 22Pachanga - 1990 Pachanga 22 - Click Here - Built502/Bravo - 74.5 GPS 454BAJA - 1995 Baja 22 Caliber - Click Here - Modded 454 / Bravo - 74.0 GPS 223 Formula - 1989 Formula 223 - Click Here - Merc 500EFI / Bravo - 73.9 GPS cookin - 1998 Sting Ray 220SX - Click Here post 606-608 - Built383/Bravo - 73.3 GPS Need For Speed - 93 Baja 204 - Click Here - Built 355/Alpha - 73 GPS jj quest - 22 powerquest Raizor - Click Here - 7.4LMag/385HP/Bravo - 72.8 GPS 201liberator - 1988 201 Liberator - Click Here Built 383/Bravo - 72.1 GPS dbkski - Cobalt 233 - Click Here - 502MPI/Bravo - 72.1 GPS Donzi18 - 1998 Donzi 22 Classic - Click Here - 72 GPS thecurti - 1998 Stingray 230sx - Click Here - 502MPI/Bravo - 71.9 GPS Jetboy - Stingray 230SX -Click Here - 496HO - 71.6 GPS ACrooks69 - Stingray 230LX - Click Here - 383sbc/Bravo - 71.2 GPS Stingray468 - 1989 Stingray 22' - Click Here - 468cid BBC - 70.9 GPS Chip - Stingray 230SX - Click Here - 454Mag - 70.2 GPS Forrest - 1972 Donzi 16 Ski Sporter - Click Here - Modded 290hp 302 Ford / Alpha SS - 70.1 GPS RedStripe - 1988 Baja 196 Sport - Click Here - 70.1 GPS |
rest of list
=========================================== ken2 - Four Winns U-17 - Click Here - 302 Ford 220hp/Volvo - 69.0 MPH GPS Ranman - 1997 Donzi 18 Classic - Click Here - 300HP/350Mag/Bravo - 68.7 GPS hump - Stingray Maxim I 20' -Click Here - 5.7mod/Alpha - 67.5 GPS Bomar76 - 94 Baja 22 Caliber Twilight Cruiser - Click Here - 385sbc / Alpha - 67.2 GPS 87Pachanga22 - 87 Pachanga 22 - 67 GPS thesledhead - 99 Nordic Sprint 22' - Click here - 66.6 GPS Mkos1980 - 90 Chaparral 2150SX - Click Here - 5.7/Alpha - 65.2 GPS FreeSpirit - 18'4" Glasstream Freespirit - Click Here/Pg8,Post152 - 350mag/Alpha - 65 88maxim - '1988 22' Stingray Maxim 3 - Click Here - 330hp 454/ Bravo - 65GPS AFBRYAN - 21' Baja Islander - Click Here - 330HP 7.4L - 64.9 GPS Hardcandy - 1994 Donzi 18 Classic - Click Here - 350 Mag/Alpha 1 - 64.7 GPS Crmax - 1999 20' Wellcraft Excalibur - Click Here - 64.6 GPS Horsepower - 24 Mariah (22', 23'6" w/platform) -Click Here - 502/Bravo - 64.2 GPS HTRDLNCN - Chaparral 21XLC - Click Here - 509BBC/ Alpha - 63.9 GPS mariahss1 - 21 Mariah - 63.5 GPS Paisan - 1994 Baja 22 TC - Click Here - 63.4 GPS TomZ - 4 Winns Santara - Click Here - built 383/SE Alpha - 63.2 GPS brivander - 1992 Four Winns 221 Liberator - Click here - 502 / OMC - 63 GPS 206LSdrvr - 1989 Formula 206LS - Click Here - 62.7 GPS jstrahn - 1996 Four Winns U-17 - Click Here - 302CI-220HP/Volvo SX Drive - 62.7 GPS Tejas Raz - Checkmate Persuader 219 - Click Here - 350Mag/Alpha - 62.5 GPS Blackwishbone - 2002 stingray 22SX -Click Here - 62.4 GPS Velocity Driver - 23' Velocity - Click Here -330hp7.4 - 62.3 GPS jeremyanderson - 2002 Powerquest 22 Raizor - Click Here - 383SBC - 62 GPS JustWishin - 20ft Baja Outlaw - 61 GPS mtnrat - 81 Campion Christina 180 - Click Here - 383sbc/Volvo duoprop C6 - 60.2 GPS Caincando1 - Baja 190tc - Click Here - 5.7 Mag/Alpha- 60 GPS stinger312 - 1986 Chris Craft 222 stinger - Click Here - 60 GPS BBdobb - 1991 Powerquest Spectra 222 - Click Here - 7.4 330HP - 60 GPS MPM - 1996 Scarab Sprint - Click Here - 4.3L / Alpha - 60 GPS Chrisf695 - 1989 Powerplay Integra Xlt-185 - Click Here - 383 SBC - 60 GPS =========================================== ducHunter - 92 211 Checkmate - Click Here - 59.3 GPS Eclipse454 - 1991 Wellcraft 216XL Eclipse - Click Here - 7.4/Bravo - 59.2mph GPS Cuda - 1982 22 Donzi Classic - 59 GPS n20stroker - 1986 Thompson 196CC - Click Here - 5.7 / Alpha - 59mph GPS FTM - F206 Formula - Click Here - 5.7 330HP GM Crate / Alpha - 58.9 GPS Mattyboy - 1967 Donzi 16 - Click Here Ford 351w Volvo 250 - 58.7 GPS Bomar76 - 1994 Baja 22 Caliber Twilight Cruiser - Click Here - 5.7/Alpha - 58 GPS corckdog1 - 1997 Glastron GS 209 - Click Here - 5.7/Alpha - 58 GPS bm250r - 1994 Baja .22 Caliber - Click Here - 350Mag/Alpha - 55.3 GPS regal-lover - 87 Regal Majestic - Click Here - 355/385hp - 55 GPS JimG-1970 Donzi 18 2+3 - Click Here -351W Holman Moody Volvo AQ250 - 54.7 GPS Intruder88 - 86 Mirage Intruder - Click Here /pg51,post1003 - mod 5.7 - 54.5 GPS eyeinstine - 85 Formula F3-ls - Click Here - 54.0 GPS winterfunguy - 1978 19' Cobalt 19DV - Click Here - 355ci 330hp - 54 GPS Littlewake - 21ft VIP Vindicator - Click Here - 53 GPS LIDave - 1983 Celebrity 210V - Click Here - 355 sbc /Alpha - 53mph GPS 35thls1ss19 - 223ls Formula - Click Here - 454/Alpha - 52.8 GPS Take It Easy - Wellcraft Elite 210XL - Click Here - 52.1mph GPS 201_Libby - 201 Liberator - Click Here - 350/King Cobra - 52.4 GPS BabyScarab - 1993 Scarab Sprint 18' - Click Here - 3.0L - 46 GPS |
Originally Posted by TomZ
(Post 4645937)
I have not been as active on the forum as I used to be so I'm chiming in a little late.
A good group of us probably 7-8 years ago or so were really running some good numbers with small boats. Scarab's, Challenger's, Velocity's, Donzi's, Chris Crafts, Sea Rays... some had some fast, I mean, really fast, boats! A lot of us were in the upper 70's and over, and there was a good amount of small block knowledge being posted. Those were some fun days! If I were you, I would pony up the cash to do this: GM part number 12681432, new Vortec 350 long block at about $1900 bucks. Replace the camshaft with a GM LT4 "Hot" camshaft at about $250. Replace the valve springs and retainers with factory GM/Chevrolet LS6 Z06 "yellow" beehive springs. The rest of the valvetrain will be good as-is. Use your existing parts (Thunderbolt ignition, intake manifold, water pump and accessories), and a stock 750 Holley marine carb. Set the all-in timing at 32 degrees. You'll make 375-390 horsepower with the factory exhaust. If the bottom of the boat is good, using a 1.50 drive ratio (which the boat should have) and your 21P prop should get you well into the 60's; any day, every day. It will sound good, and will run like a sewing machine. I had a mishap with a 385 that I built (valvetrain,broken valve and pistons); the above is basically what I put together on the fly, and had back in the boat, running, in a couple of weekends (mine was used/refreshed from Craigslist for a whole whopping $900 plus the cost of the springs, retainers and gaskets). I would not get into having someone build something for you, not at this level. The factory short block is that good as-is. Few questions if you don't mind? 1. I have a mechanical fuel pump, how do I resolve that with this motor, looks like it doesn't have the opening on the side of the block for one? 2. My Gen 1 non roller block flywheel, will it fit this motor? 3. Does it matter that the heads don't have Inconcel (sp?) Valves? I've been told that marine valves need to be different than autos? 4. Should I go ahead and replace my coupler while the motor is out? Thanks a ton gentlemen, sorry to bump this thread but I'm getting ready to pull the trigger on something soon and wanted this final bit of feedback. Cheers! Heath |
Answers to your questions.... 1. Run an electric fuel pump. It doesn’t need to be anything fancy. Carter has one that should work well: https://www.jegs.com/i/Carter/180/P4...SABEgKHtPD_BwE 2. You’ll need a 1-piece seal flywheel. Check in the swap shop or post in the parts wanted section. Easy to find. 3. The factory valves are fine. Changes are really needed when you’re looking at supercharging, etc. 4. I’m assuming you have the coupler that bolts to the crank. If you do, it’ll need to be replaced to match. If yours is the style that bolts to the flywheel itself, check it for signs of twist or a breakdown of the rubber. The small block coupler is pretty strong. They tend to go bad from misalignment. Good of luck with the build! Keep this thread updated. |
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