Can I use an Automotive engin in my 20' Invader

Surfceo · Dec 30, 2003

I have a I/O in my 1989 20' invader. I am not sure what brand of block it is (one mechanic says Chevy and another says Volvo) but regardless it is a really big 4 cylinder (~165 HP). The outdrive is a mercruiser It is my first boat and i scrapped to come up with the 4k to purchase it. At this point i am being told it is going to be anywhere from 3 - 6k to get it running again. I do not run it far offshore and do not plan to. The first cylinder has no compression and the mechanic says the block and head is shot. I have a very good source for auto parts and as a replacement, I would like to put a automotive 6 or 8 cylinder engine in the boat, are there pro's and cons dealing with matching up the transmission and the exhaust?? Any other information or references you could lend would be most appreciated My two e-mails are mfttex@yahoo.com mark@astsurf.com Thanks Mark

ZmOz · Dec 30, 2003

Re: Can I use an Automotive engin in my 20' Invader

It's probably a chevy with a volvo outdrive. Yes, you can use an automotive engine, but it should have a marine cam. Also it's probably not going to last as long as a fully "marinized" engine. If you want to keep the same size engine, getting a block and heads from a car would be probably exactly the same as what you have. If you want a bigger engine you can DEFINATELY do WAY better than $3-6k. Hell, you can get a supercharged 454 built for a jet boat for less than that...

DJ · Dec 30, 2003

Re: Can I use an Automotive engin in my 20' Invader

It's neither a Chevy or Volvo if it is as you desribe it. It is more than likely a 3.7L Mercruiser. It was an engine built by MerCruiser. It uses a block cast by Mercury with a standard Ford 460 head. Do a search on this board using the search criteria, "Merc. 470" or "3.7 Liter. The drive can handle a bigger engine, yet converting over the engine bed may be a project.

mercrewser · Dec 30, 2003

Re: Can I use an Automotive engin in my 20' Invader

I would invest my money in another boat without that engine, or find a used engine. Find differnt mechanics, those guys are idiots. I'm a carpet cleaner and can tell you that its a Merc 465. its also freshwater cooled. U can auction off those engine parts on ebay.

Ralph 123 · Dec 30, 2003

Re: Can I use an Automotive engin in my 20' Invader

Go to amazon.com, search for "Small block chevy marine performance" and read the free excerpt there which talks about all the differences between a marine engine and automotive engine. For saefty sake (and by USCG regs) you must have a marine carb, starter and altenator. Marine versions of these components help prevent the boat from exploding when fuel vapors build up in the engine compartment. Fuel is heavier than air and settle in the lowest part of the boat naturally. In an auto, they hit the ground and quickly disapate and are not an issue. In a boat they sit in the bilge and accumulate. Marine starters and altenators are built to prevent sparks from igniting these fumes. A marine carb will also not spill fuel into the compartment if it overflows.

Walt T · Dec 30, 2003

Re: Can I use an Automotive engin in my 20' Invader

You got ripped on the boat. Those mechanics are hoping to rip you. Cut your losses. Chalk it up as a very expensive lesson learned and get familiar with E bay and unload it. I hope you don't get too turned off from boating.

rodbolt · Dec 31, 2003

Re: Can I use an Automotive engin in my 20' Invader

hello why dont you post the model and seriel numbers from the drive and engine. then I will tell you to buy the manual. then read the book a few times while chewing wheaties. then pull the cyl head and see. its really rare that the block and head go POOF. the 3.7 motor was a very stout performer but it did have some quirks. if the exhaust riser clogged and they clog easily it will do really squirrly things that automotive techs cannot think of. DO NOT let auto techs eyeball your marine engine.unless you are with them reading the procedure from the manual. the altenator and regulator work well. dont fix them if they break. if you have a charging system failure convert it to a belt driven system. so if your gonna scrap the progect truck on down to sears buy some tools get a manual and have fun in the grease. I tell beginners to take many picures as the go and place bolts in baggies with a note about where they came from. good luck and post us back.

Bhamil · Dec 31, 2003

Re: Can I use an Automotive engin in my 20' Invader

Surfceo; OK, first things first. Look the engine over real close and list all serial numbers you can find, noting their location. Next, note the general description of the engine (what side of the head has the plugs, etc.) That engine is not a 460, I can assure you. You said it is a 4 cylinder, so it's either a Ford or a GM, and I mean GM, not Chevy. Post your results and we can go from there. I promise it's fixable. Just start with the basics.

DJ · Dec 31, 2003

Re: Can I use an Automotive engin in my 20' Invader

Surfceo (new boater) If the engine is attached to a black MerCruiser drive and has only four cylinders (count the spark plugs), IT CAN ONLY BE. a. 3.7 Liter MerCruiser (again-MerCruiser built aluminum block with a (one) Ford 460 head). Came in 165 through 185 versions. b. 2.5 Liter GM based-all cast iron. 120 to 140 hp. c. 3.0 Liter GM based-all cast iron. 130-135 hp. I still think is the first one, from your description-165 hp.

bluewater19 · Dec 31, 2003

Re: Can I use an Automotive engin in my 20' Invader

Ben, It is my understanding from my mercruiser manual that The mercruiser 3.7 is a ford 460 big block V-8 with 4 cylinders lopped off. I belive that mercruiser did this to make a high torque 4 banger because the gm 4 cyl motor could not be made relible at the power levels that fall beween the gm 4 cyl and v-6. But thats just what the book says.

Surfceo · Dec 31, 2003

Re: Can I use an Automotive engin in my 20' Invader

Originally posted by djohns19: It's neither a Chevy or Volvo if it is as you desribe it. It is more than likely a 3.7L Mercruiser. It was an engine built by MerCruiser. It uses a block cast by Mercury with a standard Ford 460 head. Do a search on this board using the search criteria, "Merc. 470" or "3.7 Liter. The drive can handle a bigger engine, yet converting over the engine bed may be a project.

By a project - my friends and I have dropped engines in cars before and made custom mounts and what not to line everything up - would the swap in my boat be a bigger project in your opinion? Thanks for your feedback Mark

Surfceo · Dec 31, 2003

Re: Can I use an Automotive engin in my 20' Invader

Originally posted by ZmOz: It's probably a chevy with a volvo outdrive. Yes, you can use an automotive engine, but it should have a marine cam. Also it's probably not going to last as long as a fully "marinized" engine. If you want to keep the same size engine, getting a block and heads from a car would be probably exactly the same as what you have. If you want a bigger engine you can DEFINATELY do WAY better than $3-6k. Hell, you can get a supercharged 454 built for a jet boat for less than that...

Thanks for your feedback - It seemed like i was getting hosed by these mechanics. The guy i take my truck to when the repair is above my skill level or tool inventory gave me similar feedback but he has limited time in the water. Again thank you mark

Surfceo · Dec 31, 2003

Re: Can I use an Automotive engin in my 20' Invader

Originally posted by Ralph Spencer: Go to amazon.com, search for "Small block chevy marine performance" and read the free excerpt there which talks about all the differences between a marine engine and automotive engine. For saefty sake (and by USCG regs) you must have a marine carb, starter and altenator. Marine versions of these components help prevent the boat from exploding when fuel vapors build up in the engine compartment. Fuel is heavier than air and settle in the lowest part of the boat naturally. In an auto, they hit the ground and quickly disapate and are not an issue. In a boat they sit in the bilge and accumulate. Marine starters and altenators are built to prevent sparks from igniting these fumes. A marine carb will also not spill fuel into the compartment if it overflows.

I understand needing a safer starter with the fumes and all.... Why carberator as well? Pollution? Thanks for your advice - Mark

jee70611 · Dec 31, 2003

Re: Can I use an Automotive engin in my 20' Invader

On marine carbs, the bowl vents are routed so that they will dump any fuel that comes out of them back into the bowl. Also, I believe the throttle shaft has journals to return the fuel to the engine if it was to try and leak through the bushing. The bowl vents are often referred to "j vents" or something of that nature. DO NOT USE and automotive carburetor in an enclosed engine compartment. Not only is it dangerous, but if something does happen and they find that it wasn't a marine carb, you could end up in PRISON if you survive. James

salty87 · Dec 31, 2003

Re: Can I use an Automotive engin in my 20' Invader

more like explosion, marine carbs have flame arrestors to stop backfires from flaming up and j tubes to direct excess gas back into the carb throat and not into the bilge should there be any. these are coast guard regulations.

mercrewser · Dec 31, 2003

Re: Can I use an Automotive engin in my 20' Invader

Mark, just understand that the engine is neither ford or gmc, its Mercruisers own (crappy sorry) design. Mecahnics will charge you more than the boat is worth to fix it. I agree pull the head and see, also check your manifold. Replacing with auto engine will give you more headacches. Look for a used engine local or get rid of the boat. The engine should say 465 OR 165 on top of it and it should have FWC, Antifreeze cooled (heatexchanger on front of engine). Also it has a crappy stator charging system.

Surfceo · Dec 31, 2003

Re: Can I use an Automotive engin in my 20' Invader

Originally posted by rodbolt: hello why dont you post the model and seriel numbers from the drive and engine. then I will tell you to buy the manual. then read the book a few times while chewing wheaties. then pull the cyl head and see. its really rare that the block and head go POOF. the 3.7 motor was a very stout performer but it did have some quirks. if the exhaust riser clogged and they clog easily it will do really squirrly things that automotive techs cannot think of. DO NOT let auto techs eyeball your marine engine.unless you are with them reading the procedure from the manual. the altenator and regulator work well. dont fix them if they break. if you have a charging system failure convert it to a belt driven system. so if your gonna scrap the progect truck on down to sears buy some tools get a manual and have fun in the grease. I tell beginners to take many picures as the go and place bolts in baggies with a note about where they came from. good luck and post us back.

I am having a good time rolling around in the grease (it keeps me out of the bar!). I had it running so nice and then when flushing the thing after a cruse in the SD bay it ran out of gas (my bad), but when i filled it up and tried to start it I got nothing. I pulled the hose from the fuel pump and it was getting fuel, I pulled the plugs (replaced two week earlier) and their was spark. I had the starter rebuilt a month ago as well as putting new solenoid on (but the $200 starter rebuild will turn out to be part of the problem), I just was dumbfounded and figured it would be a good gesture to send it to the boat store that has given us (I went in on this vessel with a good buddy who is more experienced with engines I do the electrical!) the most advice up to this point and just have them diagnose it so we could get back in the water (winter swells are starting). OK - the guy who inspected it wrote: #1 cylinder has no compression, bent pushrod, starter has excessive draw, blowby is excessive just while engine is turning. His face-to-face explanation was that moisture got sucked into the cylinder from the exhaust because of the bent pushrod, that corroded the cylinder and is why the block is shot and I need to replace the whole thing. I replied with "DAMMIT! Are you sure it's not something cheap like a plug wire!" he laughed and said "not a chance" I inquired how it is the $200 starter rebuild has already gone to ****, and he assured me that the place they take it would do it again for no charge. I am over this guy and need to get educated on this stuff so I can make good decisions when dealing with the mechanic and when out on the water and things go wrong. For instance if I was doing my homework it looks like I could have bought a new starter for under 150 through this site instead of paying more to fix the old one!!!! I am not giving up, I love being on the water, taking the girls on rides and really want to catch my first yellowtail next summer (which is just around the corner). As is I am double bummed having surf crowded waves now that the boat is out of commision (we usually go out to the point of the peninsula on the SD bay where there is no beach access) Back to some specific Qs: What is blowby? If all the other parts on the motor are OK, should I just start hunting for a new replacement block/heads and keep it a 4 banger? I could pick up an automotive engine for under 1K and Im sure my normal mechanic (who is very trustworthy) would help me keep it running. So many Q's .... So many options!!!!!!!!! Who ever else is reading this - let me know what you think Thanks Mark

ZmOz · Dec 31, 2003

Re: Can I use an Automotive engin in my 20' Invader

Sounds to me like you could have the block bored out and get some new pistons and be set. You should be able to get a 4 cylinder block bored out for under $70.

BMDODGE · Dec 31, 2003

Re: Can I use an Automotive engin in my 20' Invader

check this out - does it look like this ???? web page e-bay is the place to look for the motor..that is if your going to keep the boat - thank's bruce

DJ · Dec 31, 2003

Re: Can I use an Automotive engin in my 20' Invader

Surfceo (new boater), The engine on e-bay, I believe, is what you have. That engine is still serviceable. No, it is not one half a 460 Ford. The block is UNIQUE to Mercury Marine and the head is off of a Ford 460. So, a car engine CANNOT be had of the same type. With that said. You can still buy those long blocks. Check here on iboats. Also, the stator based charging system was troublesome, as mentioned. There are kits to convert them to a more traditional marine alternator system. As I recall, they are about $500.00. Another option is to upgrade it to the 185 HP version which had a four barrel carburetor and a larger heat exchanger. With all that said, if you decide to drop in a V-6 or V-8, get a MARINE engine and keep all the ancellary parts marine. COMPLETE-NEW marine engines with outdrives can be had for $6 to 8,000.00. Shop around. You DO NOT want to mess around with auto parts on an inboard marine engine. There have been too many lives lost after the big KABOOM that may result from an automotive conversion. Be safe, be smart.

Can I use an Automotive engin in my 20' Invader

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