73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Whitfield on June 12, 2012, 04:12:42 pm
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I have a special cam from a 1984 Chev marine 350 that I want to swap into a vortec engine. Can I set the Vortec up for the flat tappet hydro lifter cam from my 1984?
Cam is Reverse rotation (engnie spins backwards), A reverse rotation Vortec cam set up with distributor gear and oil pump is $1200.
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Are you planning on running the engine in reverse?
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Are you planning on running the engine in reverse?
There is the question of the day!
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Yes... I tried asking boat guys and I get lots of silly answers. They told me my Suburban motor would explode pistons when I turned the key due to off set wrist pin. I am currently running a 1991 (Suburban take out) Chev 350 ~ Factory hydro Roller 130K miles that I swapped to flat tappet and reverse rotation. 50+ hrs in the boat now / Runs good / burns oil / compresson is off on (2) cyls.
I've got a 70k 1997 (Yukon Take out) VORTEC under the bench looking for a home.
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I could be wrong here, but I believe that by turning your engine backwads, it would reverse everything that is suppose to be turning the other direction. Including flywheel ?
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He's running it in a boat, so flywheel is not a big deal, it is spinning a turbine. The question is what is different block and head wise between flat-tappet and roller. Many people switch older blocks over to roller by changing the cam and doing some head work. So your cam should fit the Vortec block no problems.
You'd need to change to valve system over to flat-tappet style and probably use the pushrods you have. What are you going to run for an intake?
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Thanks,
I wasn't sure about the block casting but keep hearing that the 5.7L Vortec bottom end is same / similar to my 91 350. I expected I have to make the valve train changes / push rods ect... Just was not sure about the Crank snout / timing gear area. For some reason the Marine MFG's went with a custom reverse rotation roller cam for the OEM Marine vortec. These very limited production cams bring BIG $$$ on the open market ~ where as the more common reverse rotation flat tappet cams are normal priced.
I was considering the standard Edelbrock Performer or Performer RPM Vortec intake. White full EFI would be nice I'll stick with the Holley marine carb for now.
~ Also for those not familiar Chevy Marine reverse rotation (Non Vortec / Before Vortec) uses gear to gear so the cam and distributor actually spin correct direction ~ but cam must be Mfg'd to feed the cylinders running in reverse order.
(http://www.promarengine.com/images/454Rev.jpg)
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I just did a search to see what is involved in a reverse rotation engine. They say the oil seals are diffrent at the crank, wich makes sense they have ribs to divert the oil back into the engine. running it backwards could pump oil out of the engine. There was something about the crank oiling. And one big thing is the difference in machining tolerances. Marine engines run cooler than one in a car. The pistin gets less heat to expand in the bore.
I'm no expert and I like to do everything myself and based on some bad marine engine experience I would not attempt this. FYI. There is alot of differences between a marine and auto engine.
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If you do run a flat tappet cam, be sure and run the zinc additive in your engine oil.
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Thanks for the advice ~ I'm running an automotive engine now.
On the zinc / ZDP I'm currently running the Shell Rotella T Diesel engine oil ~ which as I understand has me covered.
AS far as bore tolerances ( I could debate for pages on this) ~ But I'm comfortable with the results thus far, If I build an engine I'll go the local machine shop marine route but for now it is all about something for nothing and getting the good used parts out from under the bench and putting them in place to earn there keep.
Seals / yes gotta change them to the reverse rotation seals.
$1200 boat is gonna have to earn that $5k marine engine and if a $750 automotive engine works out meanwhile then it might just live there for a while.
(http://i9.photobucket.com/albums/a53/whitfimb/P1000259.jpg)
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Shell rotella does not have enough zinc. High zinc oils are bad for catalytic convertors which most new cars have these days including diesels. You need about 1220-1500 ppm of zinc, Rotella is about 800 ppm . There is a lot of research out there, but not a lot of information on Zinc content per quart of oil with the manufacturers.
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Do you have a perfered Zinc addative? I'm concerned about the need for zinc in my $3k 76 Caddy 500 in my 1988 V3500.
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Comp cams and Trick Flow make an additive you can get it from Summit or Jegs. Its basically any break-in additive or oil with advertised high zinc content.
Lucas makes one that I found at Oreilly auto parts here in Houston.