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Thread: 350 Vortec build help

  1. #1
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    350 Vortec build help

    Hi guys, I am in the process of building a 350 Vortec for My z-21. I need help and opinions with the top end. I will be using a 2000 5.7 4bolt main block with the stock heads. My machine shop looked at the engine and it has such low run time he is just going to freshen it up (re ring, bearing kit, brass plugs, etc) my questions are, what cam, intake, carb, combo? what should I run for an electric fuel pump? any opinions on roller rockers? I Would like somewhere between 300-350hp. I dont want to go too much more then that because of useability, and the Alpha drive. Thanks in advance, Andy.
    z21 side.jpgz21.JPG
    I did get new non white wall tires for trailer lol.

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    Comp Cams 264 hr xtreme marine cam . Send the heads to the machine shop and get new springs to handle the extra lift. If you are in fresh water or have freash water cooling the edelbrock performer rpm is a great intake and a dialed in 650 holley I think you will be real happy probably in the 350 hp range
    better to die on your feet, than live on your knees

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    i have a 350 Vortec 4 bolt that i just finished building. i put a ZZ4 cam in it with a Marine Power midrise intake and a 600 vacuum Holley carb, 1.6 roller rockers. i'm figuring around 320 hp. runs good in a 16, last time out 65 at 5500 rpm. needs more prop now.
    1999 16 Classic Black on White

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    Excellent! now talking to my machinist, he said we may have an issue with the studs pulling out of the heads with increased spring pressure, and to do a 1.6 don't I have to drill the pushrod holes?

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    the stock springs only have about 80-90# seat pressure at best, you really only need to increase it to about 125-130# on the seat with a lift safety factor of about .560 total valve lift, I believe the 3927142 GM springs would be fine or even the new beehive GM replacement that a couple company's offer... the seat pressure isn't what lifts the studs, it's the over the nose pressure using dual springs... you may have to have the machine shop cut down the guide bosses and use a positive valve seal, but this is no biggie to do. Depending on what heads you use you MAY have to open up the pushrod holes with a drill bit about 1/8" or so, once again no biggie, and I absolutely like the 1.6 rocker idea, as it makes the cam *think* it's a little bigger, typically it's a 3-4% duration increase going from 1.5 to 1.6 rockers.

    just my .02
    Charter Member - WAFNC, SBBR, KWOSG
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    [ QUOTE=$originalposter]{$pagetext}[/QUOTE]

    Running 1.6's on my set up and as Buzz said you will need to open up the pushrod holes a little, I went with Eldebrock E-tec E-200 alum heads with the larger intake and exhaust valves. Also went with the increased spring pressure in the beehive springs, we went with comp cams don't remeber the part number and went with a .510 lift mid 230's duration cam. Was told that anything over about .490ish would require the beefier springs.
    2006 CLASSIC 18 WHIPPLED MX 6.2, BRAVO 1, STAINLESS MARINE EXHAUST, LATHAM STEERING, IMCO 2" SHORTY, LABBED MIRAGE PLUS

    TALK IS CHEAP, I'M FROM THE "SHOW ME STATE" SHOW ME

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    Im running the 1.6 rollers on pressed in studs and beehive springs. The rockers are self aligining due to no guide plates. Ive taken it upstairs to 5500 for an extended time with no ill effects (yet!!). I didnt open up pushrod holes and seem to have no problem with rubbage. It sure does come alive over 3400 when secondaries open up, kinda feels like an Acme rocket strapped to the azz. lol. What do you guys think about high volume oil pumps. Was told that I may have a problem when she's spun up with cavitation due to oil being pumped to the top too fast!
    1999 16 Classic Black on White

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    I'm running a HV pump, spin it up to 6,000 and haven't starved it on oil yet, I'm running a 7qt pan with the tall merc/Wix filters that hold just under 1 qt.
    2006 CLASSIC 18 WHIPPLED MX 6.2, BRAVO 1, STAINLESS MARINE EXHAUST, LATHAM STEERING, IMCO 2" SHORTY, LABBED MIRAGE PLUS

    TALK IS CHEAP, I'M FROM THE "SHOW ME STATE" SHOW ME

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    Thanks Guys for the advise I will definitely do a high volume oil pump. My heads already have stainless exhaust valves, and are in good shape. what should I do for a timing chain? I was thinking a gear but the noise would probably drive me nuts. also carb question... mechanical or vac secondaries, and edelbrock or holley? and with the 1.6 rockers did you have to get special push rods?

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    If your going with guide plates you will need hardened pushrods
    2006 CLASSIC 18 WHIPPLED MX 6.2, BRAVO 1, STAINLESS MARINE EXHAUST, LATHAM STEERING, IMCO 2" SHORTY, LABBED MIRAGE PLUS

    TALK IS CHEAP, I'M FROM THE "SHOW ME STATE" SHOW ME

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    I havent starved yet either but I dont have a large capacity pan. The guy I work with who's been build engines for 20 years cautioned me on it. They learned the hard way on stockcar small block. Blew it to pieces first time out, oil starved lower end. Come to find out stockcar motors can't run high volume pumps cause your never out of the throttle long enough for the oil to get back to the bottom. But hey I haven't seen a drop in my pressure yet so I'm gonna TRY and not worry about it! Holley!!!! I'm running a vac. 600. Mechanicals are somewhat easier to dial in, but a properly tune vacuum works just as well. Vacuums supposed to be better on fuel, but it that was a major concerned we wouldn't have boats, right? I bought a secondary spring kit to tune how fast they open but havent taken the time to play with it. We have speed limits on the water here so I need a calm gulf day to test and tune. Single or double roller timing chain. Chuck the OEM mesh chain.
    1999 16 Classic Black on White

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    IMO, the 600 is borderline too small

    if you insist on using it, use the yellow secondary spring that comes in the multi spring kit and put 68 jets and a 6.5 PV in the primaries...
    Charter Member - WAFNC, SBBR, KWOSG
    1955 Perfect Mate
    1986 Hornet III, 502-415 TRS

    www.donzi.org


  13. #13
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    On the 350 Vortec I had in the Minx started w/a 600, and was marginal.
    It ran much better w/the larger carb I replaced it with.
    George Carter
    Central Florida
    gcarter763@aol.com
    http://kineticocentralfl.com/


    “If you have to argue your science by using fraud, your science is not valid"
    Professor Ian Plimer, Adilaide and Melbourne Universities

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    wow lots of good info here, I am planning on getting the rollers that dont require guides, my question i guess is the length. And I guess I 'll get at least a 650 holley. I already have the brand new DUI marine hei ign set up that was on it and Ive heard some chatter about the gear needing to be replace to properly mesh with the cam and not wear out, nbd. So if you guys were in my shoes, would you use the 1.6 roller rockers without putting studs in? And I'll order a large oil pan. My only other question is going to be the intake because the quadrabog on the factory one probably only cleared the hatch by 2-3". will a midrise as mentioned be ok?

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    GM sells the correct distributor gear for the roller cam upgrade..
    Charter Member - WAFNC, SBBR, KWOSG
    1955 Perfect Mate
    1986 Hornet III, 502-415 TRS

    www.donzi.org


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