79' Mercruiser Thunderbird 350 engine questions..

illtww · Apr 19, 2004

Ok, My boy didn't get down in time to de-winterize the boat and now we have a crack in one of the cylenders. I know it is a GM 350 5.7l [79' Mercrusier 260 model] engine but i am not exactly sure what will fit in its place. Mercrusier wants 3g's for a rebuilt engine. [engie block only] Here are my questions.. 1. I have a 96 350 engine out of a Buick Roadmaster Wagon. WIll this fit wihout alot of modfications? [EFI would kick *** !!] 2. Mercrusier said that 78-86 GM 350's should fit. Never told me if they were 2 bolt or 4 bolt mains. <-- does this matter? 3. Any one year have more horsepwer than the others? 4. IS there an affordable place to snag an engine for this boat? 5. Is there any other boards on the net decited to mercrusier sterndrives? Anypage with extensive knowdlegde on the 350's in the mercruisers? THanks, Travis W. {Poor College student trying to get on the lake}

mercrewser · Apr 19, 2004

Re: 79' Mercruiser Thunderbird 350 engine questions..

Dont put a car engine in it its dangerous. You can convert it but you can only use the longblock. Ignition and induction systems from the car are illegal and a seriousr fire risk. Look around for remanufactured marine long blocks and buy on with a good warranty. 3k is to much. Find and engine that matches your year. Do it right or pay big later.

TwoBallScrewBall · Apr 19, 2004

Re: 79' Mercruiser Thunderbird 350 engine questions..

I would use the long block from the car, and put the accessories from the boat onto the block. That should get you running as long as the two blocks are compatible. Basically just use the block and head from the car, and bolt everything else on from the boat engine. Just an idea.

ZmOz · Apr 19, 2004

Re: 79' Mercruiser Thunderbird 350 engine questions..

Long block should be exaclty the same except for the cam. I would use the cam from your old motor, or maybe an aftermarket one. It's not very hard to get alot more than 260hp out of a 350.

Bondo · Apr 20, 2004

Re: 79' Mercruiser Thunderbird 350 engine questions..

Hi, Welcome to the iboats forums..........

1. I have a 96 350 engine out of a Buick Roadmaster Wagon. WIll this fit without alot of modifications? [EFI would kick *** !!]

Buick,+ Chevy, are Very Different animals....... That motor Won't Fit, Even WITH Major Mods........

2. Mercrusier said that 78-86 GM 350's should fit. Never told me if they were 2 bolt or 4 bolt mains. <-- does this matter?

Actually, Any SBC from the 1950s to 1986 Will Fit....... Your motor is a 2-bolt block... You Don't need a 4-bolt......

3. Any one year have more horsepwer than the others?

Yes... No..... Maybe..... It all depends on the components used......

4. IS there an affordable place to snag an engine for this boat?

About the Best Deal going is a GM Goodwrench Long Block Crate Motor, for a Pre-86 Truck.......... Change it to Brass Freeze-Plugs,+ Bolt on All the componets from Your motor...... And You're back on the water for well under $2000. You Doing all the Work.......

Or, Of course you Could go find a $100. JunkYard Motor......

5. Is there any other boards on the net decited to mercrusier sterndrives? Anypage with extensive knowdlegde on the 350's in the mercruisers?

Ya, Lots of them..... But, For What You Need to Know...... Find a copy of Dennis Moore's book, Small-Block Chevy Marine Performance....... It's the Bible, Atleast for What You're looking for.........

illtww · Apr 20, 2004

Re: 79' Mercruiser Thunderbird 350 engine questions..

OK.. I talked to dennis personally and... He sugggested a pre 72' block if i could find one because it had the flat top pistons in it. (More Performance) the later ones have (Dished) pistions for emission purposes. WOuld need to watch out where the dipstick was on the older engines because mine is a 79'. Has anyone run a 350 (pre 86 block) in their boat with DIshed pistions and it run ok? Thanks, Travis W.

TwoBallScrewBall · Apr 20, 2004

Re: 79' Mercruiser Thunderbird 350 engine questions..

Didn't notice you had a BOP block (buick/olds/pontiac). Won't bolt up like Bondo said. Sorry!

illtww · Apr 20, 2004

Re: 79' Mercruiser Thunderbird 350 engine questions..

Wondering if anyone has run a car engine (dished pistions and Stock Heads) on a boat. OR anything alsong that line.. Might also be able to sleeve the block. I plan on switching my marine cam and components over to the car block. Just want to leave the pistons and crank alon in the car block. Thanks, Travis W>

flashback · Apr 20, 2004

Re: 79' Mercruiser Thunderbird 350 engine questions..

I had a local machine shop build one up for me, 1980 4 bolt main with flat top pistons,new rods,new lifters, new cam, etc.. I have had it for two years now and it runs great, besides as one of the guys said in my post last year " I like to shake the hand of the guy that's putting it together" . It cost me about 1500.00 bucks, but I made a good friend and kept the money local.... good luck to you..............

Bondo · Apr 20, 2004

Re: 79' Mercruiser Thunderbird 350 engine questions..

illtww, What Exactly is Your Goal..???? Are you Trying to get the boat back in the water as InExpensively as Possible ?? Or, Are You Trying to get the boat back in the water, With an Engine that'll Go the Mile,+ rather Quickly at that ??? Dennis is Absolutly Right....... If You're going to Rebuild It........ The Odds of Finding a motor of those Vintages, Reading to Drop-In,+ Go.......... Are Extremely BAD..... If You're going to Rebuild a Motor, Do Yours.... All you need is a Block.....

CCrew · Apr 20, 2004

Re: 79' Mercruiser Thunderbird 350 engine questions..

Buick Roadmaster wagon is the Chevy Caprice wagon. They come out of the same plant, and it's quite possible that his 350 is indeed a Chebbie. All based on the VIN code. Just thinking out loud... -Roger

illtww · Apr 20, 2004

Re: 79' Mercruiser Thunderbird 350 engine questions..

I have given up on the 96 vortech 350... (way to much is different) (cost me 600 with 1 year warranty but i can get the $$$ back) Ultimately I would like a balance of low cost to reliability. If it is not fast enough i will throw a cam in it and a set of dennis's headers on it at a later date. I may be able to get a early 80's running 350 for ~200. IF i could just slap the marines parts on it and the marine cam and let it roll that would be great. (Don't have to tear the other engine apart etc....) A full rebuild will cost for gasket and barings etc.... ANyone runnin a stock early 80's bottom end in there boats here? Realy appreicate all the help guys. Travis W.

illtww · Apr 21, 2004

Re: 79' Mercruiser Thunderbird 350 engine questions..

sup guys? Anyone running a STOCK 350 Bottom end form 78 - 86 with the dished pistons etc.. LMK, Travis W.

Walt T · Apr 21, 2004

Re: 79' Mercruiser Thunderbird 350 engine questions..

I would imagine any boat built in the 1980's with a 350 chevy would have run on a stock bottom end.

Bondo · Apr 21, 2004

Re: 79' Mercruiser Thunderbird 350 engine questions..

I may be able to get a early 80's running 350 for ~200. IF i could just slap the marines parts on it and the marine cam and let it roll that would be great. (Don't have to tear the other engine apart etc....)

Go for It.............

79' Mercruiser Thunderbird 350 engine questions..

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