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Need a Chevy Guru

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    Default Need a Chevy Guru

    Let me start that I am a total noobie to Chevorlet engines. The new project has a 1985 sbc 350 with a cracked block. I been reading about Chevies & found out Chevorlet made a change to 1986 & later small blocks. But I can't find out what was changed. The question is will a later model small block bolt up to my 1985 bell housing & exhaust manifolds?

    Second question, I'm reading about "VORTEC" engines. What makes a vortec engine different from the standard 350? Can you run these with a carb? I do know the base 350 is rated for 260 hp & the vortec's are rated at 330.

    Third, Will a vortec block bolt up to a pre '86 bell housing? There is very little difference in price for a "remanufactured" 330 hp vortec long block vs a 260 hp basic SBC 350....Thanks in advance....-Rich
    Last edited by Redeye1620; 08-20-2014 at 06:54 AM.

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    Senior Member Hullshot's Avatar
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    Quote Originally Posted by Redeye1620 View Post
    Let me start that I am a total noobie to Chevorlet engines. The new project has a 1985 sbc 350 with a cracked block. I been reading about Chevies & found out Chevorlet made a change to 1986 & later small blocks. But I can't find out what was changed. The question is will a later model small block bolt up to my 1985 bell housing & exhaust manifolds?

    Second question, I'm reading about "VORTEC" engines. What makes a vortec engine different from the standard 350? Can you run these with a carb? I do know the base 350 is rated for 260 hp & the vortec's are rated at 330.

    Third, Will a vortec block bolt up to a pre '86 bell housing? There is very little difference in price for a "remanufactured" 330 hp vortec long block vs a 260 hp basic SBC 350....Thanks in advance....-Rich
    All the bellhousings are the same on the small blocks, the headers from your 85 will fit on the newer 350 as well. The newer small block that came out around 88 or earlier had different valve covers and they attached down the center of them instead of around the outside. Also later they changed the heads on the intake side which only had 8 bolts holding the intake down instead of 12. Regardless the headers and bellhousing will bolt up to them.
    Last edited by Hullshot; 08-20-2014 at 08:00 AM.

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    Quote Originally Posted by Hullshot View Post
    All the bellhousings are the same on the small blocks, the headers from your 85 will fit on the newer 350 as well. The newer small block that came out around 88 or earlier had different valve covers and they attached down the center of them instead of around the outside. Also later they changed the heads on the intake side which only had 8 bolts holding the intake down instead of 12. Regardless the headers and bellhousing will bolt up to them.
    Thank you Hullshot....I purchased a clean 1985 Nordic 26' Viking with a cracked block last week for $1300. Only 198 hours on the hour meter. I was going to go with a 454, but found out the expense of a rebuild, marine exhaust manifolds, intake, carb & motor mounts would be fatal to my bank account. Anyway I'm heading in the direction of rebuilt marine Vortec long block. Thanks again....-Rich

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    to add to this, the flywheel bolt pattern is different on the newer engine because of the 1 piece rear seal, and the 96 up vortec will have a factory hyd. roller cam.

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    Quote Originally Posted by sammyc57 View Post
    to add to this, the flywheel bolt pattern is different on the newer engine because of the 1 piece rear seal, and the 96 up vortec will have a factory hyd. roller cam.
    FYI, I also read I would need a new coupler to match the newer fly wheel....Not a hard swap as I understand. Thanks

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    just trying to help fella!

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    Quote Originally Posted by sammyc57 View Post
    just trying to help fella!
    And I appreciate your help!!!!!
    Last edited by Redeye1620; 08-21-2014 at 07:08 AM.

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    I don't know if you have finished this job yet or not but thought I would add a little info.

    1986 – The rear main seal was changed from a 2-piece rubber design to a 1-piece rubber design that used a mounting appliance to hold it in place. This necessitated a change in the flywheel/flexplate bolt pattern as well as requiring an externally balanced flexplate/flywheel.
    1987 – The valve cover surfaces were changed so that the mounting lip was raised and the bolt location was moved from 4 bolts on the perimeter to 4 bolts along the centerline of the valve covers (this design debuted on the Corvette in 1986, and the Chevrolet 4.3 L the year before). Also changed were the mounting angles of the two center bolts on each side of the intake manifold (from 90 to 73 degrees), and the lifter bosses were increased in height to accept roller lifters; the aluminum-alloy heads for use on the Corvette engines retained the non-angled bolts. Also, all carburetors were replaced by TBI (throttle-body injection) fuel injection.
    1996 – This was the last change for the Generation I engine, which continued through the end of the production run in 2003; all 1997–2003 Generation I engines were "Vortec" truck engines. The cylinder heads were redesigned, using improved ports and combustion chambers similar to those in the Generation II LT1, resulting in significant power increases. The intake manifold bolt pattern was also changed to four bolts per cylinder head instead of the "traditional" six bolts.

    Now regarding Mercruiser - they used the small diameter flywheel on the old small block prior to the change in 1986. On the 1986 and later engines they started using the larger diameter flywheel. If your old flywheel is the smaller diameter, the Merc bellhousing will not be large enough to fit the larger flywheel. When I did my swap I had to track down a smaller flywheel from an 86 or newer Camaro in order to fit the engine to the old bell housing - and they are a little hard to find used. As already mentioned a new coupler is required due to the different flywheel bolt pattern.

    If you have finished this swap, let us know how it turned out. Otherwise, good luck.

    Doug

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    Thanks to all for your expertses. Update, I was able to trade a used 454 long block for a complete 1998 "vortec" 350. This trade included an Edelbrock performer intake & a holley 650 carb. The short block is in the machine shop being bored .030 & fitted with flat top pistons. The crank just needed to be polished so standard is the size for the bearings. New ARP rod, main & head bolts will hold everything together. The rotating assembly will be balanced. The vortec heads have been reworked to allow for a .550 lift cam. The cam of choice is a Chevy "hot" cam from Jegs. .496 lift with 1.5 ratio stainless roller rockers. Brass freeze plugs will be installed in the block. The build plan is to try & achieve 400 HP & 400 lbs torque with a 5200 redline.

    The process is slow going as I'm using the grocery budget to buy parts. Thanks again....-Rich
    Last edited by Redeye1620; 09-24-2014 at 02:22 PM.

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    Quote Originally Posted by Real McCoy View Post
    I don't know if you have finished this job yet or not but thought I would add a little info.


    Now regarding Mercruiser - they used the small diameter flywheel on the old small block prior to the change in 1986. On the 1986 and later engines they started using the larger diameter flywheel. If your old flywheel is the smaller diameter, the Merc bellhousing will not be large enough to fit the larger flywheel. When I did my swap I had to track down a smaller flywheel from an 86 or newer Camaro in order to fit the engine to the old bell housing - and they are a little hard to find used. As already mentioned a new coupler is required due to the different flywheel bolt pattern.

    If you have finished this swap, let us know how it turned out. Otherwise, good luck.

    Doug
    I was lucky to find a small fly wheel on craigs list for $40 & it bolts to the new crank. And as an added bonus, the stock coupler bolts right up to the new flywheel. Don't have to buy a new coupler.

    The machine shop still has the engine. I went with the Chevrolet "hot" cam with 218-228 duration & .492 lift & 112* lobe centerline. A set of self aliging roller rockers will top off the engine. Should be pushing 350-370 HP when all is said & done....-Rich
    Last edited by Redeye1620; 10-10-2014 at 10:09 AM.

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