Sbc?

[69vette427]

OK a couple of questions. The 5.0 is a 305 chevy but what are the differences between a marine engine and regular engine. I have a few things been sitting in the garage for a sbc. Was thinking if the cams are similar I would put one in that would improve performance and sound cool too.Whats yout thoughts on that?
new guy

 

[John_S]

Re: Sbc?

Typically, the ones that make that "cam" sound, do have too much overlap for wet exhaust.

What year 305 are we talking?

 

[greg82255]

Re: Sbc?

Is the cam you have a truck cam or some kind of performance street cam? If it is a truck cam it may be OK, but as John and Bubba said you have to be careful on the overlap or else you could end up with cylinders full of water.

 

[69vette427]

Re: Sbc?

OK Thanks for the info. Didn't know that I would be sucking in water that way. It's a 1998 Marada 5.0

 

[John_S]

Re: Sbc?

It's a 1998 Marada 5.0

Check to make sure you have vortec heads. If your engine was also made in '98, highly likely it is.

If you have a 2brl carb, you can consider going to 4brl. You should pick-up 20-30HP. If you have a volvo, it may only be a carb change. They use a 4brl intake with a plate to run 2brl. If a merc, would need intake as well.

If you have a MPI, you already have more HP than the 4brl will provide. Any significant mods may require programming changes.


If you have the standard head 305, still may consider a 4brl upgrade. Upgrading to vortec heads and 4brl is also a possibility, but going with a 350 is probably a better option.

 

[greg82255]

Re: Sbc?

2 years ago I changed out the 2bbl on my 305 for an edelbrock performer and holley 4160 4bbl. Didn't gain anything on the top end but out of the hole was better. I've seen people on this site claim they gained as much as 5mph by simply changing to a 4bbl, so my case might have been because I didn't tune it right. Still, if you want some noticeable power finding a used 350 or new 350 long block is probably the best option.

You could always build a 383 too!

Check to make sure you have vortec heads. If your engine was also made in '98, highly likely it is.

If you have a 2brl carb, you can consider going to 4brl. You should pick-up 20-30HP. If you have a volvo, it may only be a carb change. They use a 4brl intake with a plate to run 2brl. If a merc, would need intake as well.

If you have a MPI, you already have more HP than the 4brl will provide. Any significant mods may require programming changes.


If you have the standard head 305, still may consider a 4brl upgrade. Upgrading to vortec heads and 4brl is also a possibility, but going with a 350 is probably a better option.

 

[John_S]

Re: Sbc?

Given your serial number in the other thread and SM #24, you have vortec heads.

If you are looking for some extra power, the Performer EPS Vortec intake manifold and Edelbrock 1409 marine carb should be a good match for you. Should net you close to another 30HP. 250HP@prop. There are some additional parts: 4brl flame arrester, fuel line, and gaskets. It is a straight forward change.

PS: If you are raw water cooled, and boat in the salt or brackish water, should get a marine version of intake. It will have brass or other coating in the water passage to prevent corrosion.