Engine rebuild & Carb advise

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   Hello all from sunny South Africa,

We own a 1980 Ski Nautique with a 350 Mercruiser.
It has been about 25 years since the engine was last redone and it has now started to leak oil, The head gasket was also blown on our last ski outing.
We are now looking at a complete engine rebuild and would like to up the power a bit as we do a lot of barefoot waterskiing and could do with a bit more speed.

The easiest option would be to up the compression a bit say to 9.5:1 but this would require re-jetting the carb which is a Rochester Quadrajet. It seems that here in South Africa parts for the Rochester are very hard to come by and so our engine builder has recommended we get a Edelbrock marine carb.

My Questions are firstly if this swap to Edelbrock is a good option? and if so which one?
Would the swap require a new intake?

We would also like to install a HEI ignition system and would like to know what would need to be considered when doing this?

Any comments would be appreciated and if the topic has been covered before if you could please direct me to previous posts.

Regards,
Warren.

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Helix1511 Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: February-16-2018 Location: South Africa Status: Offline Points: 4	Post Options Post Reply Quote Helix1511 Report Post Thanks(0) Quote Reply Topic: Engine rebuild & Carb advise Posted: January-04-2019 at 2:56pm
	Hello all from sunny South Africa, We own a 1980 Ski Nautique with a 350 Mercruiser. It has been about 25 years since the engine was last redone and it has now started to leak oil, The head gasket was also blown on our last ski outing. We are now looking at a complete engine rebuild and would like to up the power a bit as we do a lot of barefoot waterskiing and could do with a bit more speed. The easiest option would be to up the compression a bit say to 9.5:1 but this would require re-jetting the carb which is a Rochester Quadrajet. It seems that here in South Africa parts for the Rochester are very hard to come by and so our engine builder has recommended we get a Edelbrock marine carb. My Questions are firstly if this swap to Edelbrock is a good option? and if so which one? Would the swap require a new intake? We would also like to install a HEI ignition system and would like to know what would need to be considered when doing this? Any comments would be appreciated and if the topic has been covered before if you could please direct me to previous posts. Regards, Warren.

MrMcD Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3588	Post Options Post Reply Quote MrMcD Report Post Thanks(0) Quote Reply Posted: January-04-2019 at 5:01pm
	Edelbrock and Webber sell a new replacement Quadrajet carb, not cheap but available. Also available is the Edelbrock 4bbl carb that is a copy of the Carter 4bbl carb. The Carter was a very good carb, I ran one on my 78 Nautique for 5 years trouble free. The Carter design is different and would involve moving your fuel line and throttle cable as well as the Manifold may or may not work. You would have to read up on bolt patterns. How many hours are on the block? There are many options to increase horsepower in a GM 350, aftermarket heads, the block can be converted to a 383. Even the newer factory Vortec heads can offer a 30-40 HP bump but you would need a new manifold.

KENO Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 10637	Post Options Post Reply Quote KENO Report Post Thanks(0) Quote Reply Posted: January-04-2019 at 8:24pm
	Edelbrock (and Weber) marine carburetors are a square bore pattern and you'd need an adapter to be able to bolt an Edelbrock to your present Quadrajet manifold They're readily available, here's a link link With a 350 Chevy you'd probably want an Edelbrock 1409 600 cfm carburetor or you can find remanufactured ones from Edelbrock with a 9909 part number. There's also a bigger 750 cfm 1410 ( or a 9910 remanufactured version of it} with the same square bore pattern. Here's a link to a popular HEI marine Chevy distributor link

Helix1511 Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: February-16-2018 Location: South Africa Status: Offline Points: 4	Post Options Post Reply Quote Helix1511 Report Post Thanks(0) Quote Reply Posted: January-06-2019 at 1:26pm
	Thanks guys for the comments! The block is just short of 1700 hours.

JoeinNY Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: October-19-2005 Location: United States Status: Offline Points: 5693	Post Options Post Reply Quote JoeinNY Report Post Thanks(0) Quote Reply Posted: January-06-2019 at 2:09pm
	Good advise above but i would emphasize the vortec heads. Real useable ski boat hp is in those factory vortec heads if you can get your hands on some. The new intake can be gotten to support the heads and an edelbrock or holley squarebore. Good advise above but
	1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" Holeshot Video

MrMcD Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3588	Post Options Post Reply Quote MrMcD Report Post Thanks(0) Quote Reply Posted: January-06-2019 at 5:00pm
	At 1,700 Hours you may be well served to freshen the whole engine. The crank may be perfect or worn you won't know till tear down. Good time for new bearings, both crank and camshaft bearings. Inspect all parts and make decisions about what is needed. The block will likely need to be bored oversize and new pistons installed. The small block GM is the least expensive engine to build and all parts are available. You might also consider a Crate Engine shipped to you ready to drop in. You will need to know if it is standard or reverse rotation as some parts may change. Camshaft and rear main seal are my first thoughts if you have reverse rotation. Being in South Africa I am sure your options are limited.

Helix1511 Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: February-16-2018 Location: South Africa Status: Offline Points: 4	Post Options Post Reply Quote Helix1511 Report Post Thanks(0) Quote Reply Posted: January-13-2019 at 3:11pm
	Thanks guys for the advise, we will be tearing it down in about a weak. Once its open we will see what we working with and see how much is left in the budget for upgrades.

Engine rebuild & Carb advise

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