alex722607

iTrader: (3)

Okay TGO
I have some questions. I just did a conversion from a Chevy SBC 350 to a 5.3 LS style block.

The 350 had a problem with the heads and was a pig on gas and stalled and all that stuff. At the same time my parents have a family boat that has a 305 and is grosely underpowered for a 5000 pound boat. We want to do a engine on it and due to funds appropriated towards this I figuredit would be best to utilize the 350 and slap vortec heads on it and call it a day (along with a cam swap for the marine power band). Besides the heads and intake wing change did there anything else needed to make a gen 1 1988 (it's low miles and was a jasper reman to begin with- see my swap thread for more details about it if interested) work with 350 Vortec heads? I know we could do a bunch of valve upgrades to the heads but I need to do this cheap and the faster I get it together the better so that is not a priority. Also are the vortec heads cast iron because we use raw water cooling and my dad really does not want to do fresh water cooling swap - it is very pricey.


So essentially:
Vortec 350 heads on a roller lifter 88-96 small block Chevy 350
Is it all that is needed (heads and intake ))

Is it cast iron or cast aluminum??

Night rider327

iTrader: (13)

Vortec heads are cast iron, and if you stay with a stock or very mild cam (less that .450" lift) all you need is the heads, intake, intake gaskets (fel pro MS98000T).

The 88-96 engines factory rockers, pushrods, valve covers will fit the vortec heads.

alex722607

iTrader: (3)

Perfect thank you.

Jonesyfxr

iTrader: (2)

I'm building a 355 for my 21 foot boat as we speak. There are some power concerns with certain out drives. I can guide on some cam choices too. Let me know what you currently have.

You can get a cast iron Vortec intake but they are pricey, unless you can find one on here. If you run in fresh water you can grab an aluminum intake.

alex722607

iTrader: (3)

good to have someone doing something similar. This is going into a 1988 25 foot cabin cruiser.
Thanks for help!!

The outdrive is a Volvo penta 290 DP with B3 props

Jonesyfxr

iTrader: (2)

IIRC this is the counter rotation outdrive? If it is, you are limited on power handling. As long as you don't do any crazy holeshots you should be ok. The reason your boat manufacturer used the dual props is for stern lift and torque out of the hole.

I'm limited on power with my alpha one outdrive. But I think my combo will be a touch over 300hp with the flat top pistons, cam, intake and Holley 750 carb.

I will post some links to some Vortec 350 builds from Offshoreonly.com.

Fast355

iTrader: (2)

I would suggest the GM 395 marine roller cam if the 88 350 is setup for a roller cam. It is the cam GM puts in the Vortec head 350 marine engine making 300 hp. Idle is smooth and the torque curve is very strong and linear from just off-idle.

Jonesyfxr

iTrader: (2)

Here you go.....

http://www.offshoreonly.com/forums/g...tec-heads.html

http://www.offshoreonly.com/forums/g...k-350-sbc.html

http://www.offshoreonly.com/forums/g...head-swap.html

If you look around you can find that 350 MAG cam used but in good shape. Just make sure you get a cam that works with stock springs or do the Alex's Parts spring upgrade kit to the heads.

Hope this helps!

alex722607

iTrader: (3)

Well this was all theoretical. The 350 that we pulled out of the GTA was shot in more ways than one. It was a jasper reman 638 block with 193 heads (probably a caprice motor). No crosshatch left at all and cylinder walls were scored bad. No compression to really speak of on cylinder 1, 3, 6. (Checked them three times to be sure) I pulled the heads and discovered that the head gaskets were about to fail between cyl 3&5 and cyl 4&6 - my dad says I had about 2 months if that before both head gaskets would have blown. - by the looks of it and the wear- it probably came from a taxi cab

kevins88

i dont even kn0w wheret0 begin. ive got the lower from a95 caprice top from 88 tpi.got worries reverse cooling hlp

alex722607

iTrader: (3)

Well an LT1 intake goes on a sbc with mods- so I can imagine the opposite could be possible. Things To keep in mind are the distributor hole, cooling neck, fuel and others - hopefully someone who knows about this stuff can chime in.

MoJoe

iTrader: (5)

Kevin did some searching and dug up this crusty thread and want to do the opposite.

kevins88

i cat seem to get this sight to come up

MoJoe

iTrader: (5)

Kevin, what is "this sight"? Help us help you. Provide us more information than "it doesn't work".

In my previous post, "this crusty thread" is a link to the other thread you've posted in here on TGO... https://www.thirdgen.org/forums/tech...ntake-fit.html

On that thread, I posted:

where the links are:
http://www.eecis.udel.edu/~davis/z28...ke_conversion/
and yet another TGO thread...
https://www.thirdgen.org/forums/tpi/...t-pattern.html

kevins88

thank you for the info.also thank you for responding.ive got a hughe mess on my hands.i might hav screwed myself beyoud repair