Vortec 350 with LT4 hot cam, questions, sorry long read :-)

steves86ta

Seaman
Joined
Jan 15, 2013
Messages
56
Hi Guys,

Ive been hanging around for quite a while, however this is my first post I believe.
I am the new proud owner of a 1980 Bahner Sport Cruiser (21?) and I love the boat. Ive taken it out a few times and it has run flawless. Now I came over from the Car world and its perfectly normal for me to not be able to leave anything alone. Hence I have decided to build a 350 for the boat that I have laying around.
The current setup is a 228 horse 305/MC-1 drive. And it runs great with a 19 pitch 3 blade prop I am able to get 54 out of it by myself. But it?s a solid 50 all day long with 4 adults. This impressed me and I figure the boat is very light (probably about 2500 lbs). But I would like more (naturally). Here are some plans and since you guys are the experts I was wondering what you think I could realistically expect?
I have a 1998 ?R? motor from a Silverado. It is a ?Vortec? headed block with less than 45000 miles. My plan is to re-ring the stock pistons, new bearings everywhere (rod, crank, and mains), then an LT4 hot cam I also have laying around. Ive done some research on here and many people have ran a setup similar to this or the exact same and for the most part I read good results.
So to sum up my long post I have a couple questions (mainly on the differences between marine and auto).
1. Since this is purely a freshwater boat, do I need to worry about special (marine) head gaskets?
2. I plan to run a edelbrock performer RPM intake, again do I need to worry about the ?marine? version?
3. Do I need a special oil pan or will a stock auto one do? I will have a windage tray.
4. Do the exhaust manifolds require special gaskets? Or will stock exhaust manifold/header gaskets work?
5. Do I have to buy the coupler that bolts to the Crankshaft? Or can I get the ?triangle? style that will bolt up to the flywheel?
I?m expecting the engine to put out approx 350-375 horse and approx 400+ ft lbs. And I know this is a light boat with a decent hull. Infact some of the research I have done say they have the same hull as an Eliminator sport cruiser? Taking into consideration the stock 305 pushed the boat to 50+ (on gps btw) what can I realistically expect from this new combination? Im expecting at the least an extra 100 horsepower and 100+ ft lbs. Just guesses are fine as well.

Thank you for your time,
Steve
 

Bondo

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Re: Vortec 350 with LT4 hot cam, questions, sorry long read :)

Ayuh,... Welcome Aboard Steve,... a few random thoughts,...

A head gasket with a SSteel fire ring is always a Good thing, 'n ya Don't wanta use a shim gaskets anyways, so go the extra few bucks for a name brand Marine set...

The exhaust manifold gaskets are "Different" in that they're 1 piece,...
Otherwise, ya can't install 'em,...
Again, a name brand 1 piece is fine, I like the Fel-pro 1404, metallic carbon gaskets..

For the Intake, I donno's Edlebrock does a Marine version, so don't worry 'bout it,...
The Carb though, Must be Marine... the 1409 is a Great choice there,...

You'll need a 168 tooth Flywheel for the newer motor, 'n ya, the triangle coupler bolts to the pressure plate holes...
Make sure the flywheel Cover clears everything though...

'n What's the Spec's on this Hot Cam,...
I'm guessin' it's Too Hot, 'n the 1 in the motor Now, would be a much Better choice...

All that, Might get ya double nickels,... donno...
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: Vortec 350 with LT4 hot cam, questions, sorry long read :)

350-375hp through an MC-1 drive???? It won't last very long.... For that sort of power, look at spending a few $$ and changing to a Bravo 1....

Here's the bad news. That extra 100+ horsepower will probably only take you up to about 60 (maybe not even that).... It the old rule of squares... to double the speed, you need the squared amount of power. ie, to get to 100 (50x2) you'd need 48,000hp (220x220)..!!! I know that sound ridiculous, by that's the way the rule works.

Chris......
 

QC

Supreme Mariner
Joined
Mar 22, 2005
Messages
22,783
Re: Vortec 350 with LT4 hot cam, questions, sorry long read :)

We like pics, Steve. I can see a Bahner being a "splash" of an Eliminator, but I am guessing the other way around. Take Bondo's cam comments seriously. Read up on "reversion" . . . ;)
 

steves86ta

Seaman
Joined
Jan 15, 2013
Messages
56
Re: Vortec 350 with LT4 hot cam, questions, sorry long read :)

Ayuh,... Welcome Aboard Steve,... a few random thoughts,...

A head gasket with a SSteel fire ring is always a Good thing, 'n ya Don't wanta use a shim gaskets anyways, so go the extra few bucks for a name brand Marine set...

The exhaust manifold gaskets are "Different" in that they're 1 piece,...
Otherwise, ya can't install 'em,...
Again, a name brand 1 piece is fine, I like the Fel-pro 1404, metallic carbon gaskets..

For the Intake, I donno's Edlebrock does a Marine version, so don't worry 'bout it,...
The Carb though, Must be Marine... the 1409 is a Great choice there,...

You'll need a 168 tooth Flywheel for the newer motor, 'n ya, the triangle coupler bolts to the pressure plate holes...
Make sure the flywheel Cover clears everything though...

'n What's the Spec's on this Hot Cam,...
I'm guessin' it's Too Hot, 'n the 1 in the motor Now, would be a much Better choice...

All that, Might get ya double nickels,... donno...

Thanks for getting back to me so quickly :)

That makes sense on the head gaskets so yes i will get those. I had planned on a "marine" carb.

As far as cam specs go, here are the lt4 hot cam specs

218/228 .525" lift on both sides (with 1.6 rockers) 112 LSA.

Heres a link to a guy thats running it, actually his build thread and he loves it. I found a few threads on here, but they are saved on my work machine and im at home now :)
Engine Build Finally Under Way!! - Offshoreonly.com

Thanks for the insight
Steve
 

steves86ta

Seaman
Joined
Jan 15, 2013
Messages
56
Re: Vortec 350 with LT4 hot cam, questions, sorry long read :)

350-375hp through an MC-1 drive???? It won't last very long.... For that sort of power, look at spending a few $$ and changing to a Bravo 1....

Here's the bad news. That extra 100+ horsepower will probably only take you up to about 60 (maybe not even that).... It the old rule of squares... to double the speed, you need the squared amount of power. ie, to get to 100 (50x2) you'd need 48,000hp (220x220)..!!! I know that sound ridiculous, by that's the way the rule works.

Chris......


48000!!! Lol yeah i understand where you are coming from. It will just be nice to have the peace of mind that the engine is new. I was hoping to push a little quicker as the 305 only pulls to about 4800 with my 19 pitch prop. I figured the 350 should push that prop a little harder if not i should be able to step up a little bigger. But i guess i shouldnt expect to much since it seems boats take a lot more to push than any of my street cars did.
 

steves86ta

Seaman
Joined
Jan 15, 2013
Messages
56
Re: Vortec 350 with LT4 hot cam, questions, sorry long read :)

We like pics, Steve. I can see a Bahner being a "splash" of an Eliminator, but I am guessing the other way around. Take Bondo's cam comments seriously. Read up on "reversion" . . . ;)

I dont know how much truth there is to that statement, its kjust something i read. But the pictures i have looked at they tend to look extremely similiar. even the paint designs.

Heres a couple pics of an orange Open Bow and one Brown Closed Bow model i found online for sale. Then the Blue boat is my Bahner. I know its a closed bow but you can see the similiarities.

Eliminator
99236_1507186_zps27e0b4ff.jpg

Boat_zps182720dd.jpg


My Bahner
photo_zps0388e776.jpg

IMG_0040_zpsdaf932fe.jpg

IMG_0041_zps57288537.jpg


So i dont know how close they are but they look pretty damn similar to me :)
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: Vortec 350 with LT4 hot cam, questions, sorry long read :)

Toss the SBC and drop a 502 in it.... marry that to an SSM7... Way to go!!!!
 

steves86ta

Seaman
Joined
Jan 15, 2013
Messages
56
Re: Vortec 350 with LT4 hot cam, questions, sorry long read :)

Toss the SBC and drop a 502 in it.... marry that to an SSM7... Way to go!!!!

Trust me i would LOVE to however that is not possible... lol i got rid of my race car to buy the boat and really want something more on the mild side. Hence the smaller cam and stock internals. Plus i can only budget about 1200 to build this 350 and thats pushing it as i have a river trip planned in a few months that i would love to have this engine built for
 

QC

Supreme Mariner
Joined
Mar 22, 2005
Messages
22,783
Re: Vortec 350 with LT4 hot cam, questions, sorry long read :)

Very typical late 70's early 80"s graphics in the gelcoat. I may do some research, but Bahner was pretty respected back in the day. Eliminator is too, but my point was that the Bahner name is nothing to put second to Eliminator. Nice ride!! Figured you were here (CA).
 

steves86ta

Seaman
Joined
Jan 15, 2013
Messages
56
Re: Vortec 350 with LT4 hot cam, questions, sorry long read :)

Very typical late 70's early 80"s graphics in the gelcoat. I may do some research, but Bahner was pretty respected back in the day. Eliminator is too, but my point was that the Bahner name is nothing to put second to Eliminator. Nice ride!! Figured you were here (CA).
Yeah the research i have been able to find everyone has loved any that they have owned. I will say i have ran it at Lake Perris twice now and went out to laughlin this past weekend. Did the run from Needles down to Havasu Springs and it did phenomenal. Rode extremely smooth, and ran perfect. Im not trying to boast but not many people were running much faster than i was able to. And i even out ran a Carrera with a bigblock and a jet with my little 305 :) i couldnt be happier. For my first boat in years i couldnt be happier i just wish it was an open bow. But it did come off of some pretty big wakes and it was way softer than anyone expected. I guess you could say im pretty impressed.
 
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