43L Differences between Marine and Automotive

"Hi all,

I`m new here and I

"Hi all,

I`m new here and I certainly don`t mean to offend anyone or step on any toes, but I need to get the straight scoop from someone who actually and verifiably knows the differences. I`ve read back through several pages of posts concerning the 4.3L engine and as is typically the case on discussion forums, I`ve noted a trend by guys who were very recently asking questions about these engines that illustrated their lack of specific knowledge and experience, not intelligence by any means, as now making authoritative but seemingly unsubstantiated statements when newbies ask questions regarding these engines and their differences. Still with me? Thanks for being patient.

So here is my scenario:

I have a `98 Bayliner Trophy 2052 that my father and I co-own. It has the 4.3 liter engine and regardless of how it happened, I know that I have a cracked block. Furthermore I`m going to offer an educated guess before I even tear into it that the crack(s) is in the oil galley under the intake manifold because the engine started and ran fine.....until it started to puke frothy oil and water out through the air cleaner. I understand that I have major engine problems and accept that the best case scenario is a short block and worst case is probably a long block, maybe even new manifolds. That situation is what it is, no crying about it now.

The next factor is that by default, everything financial about this boat ends up being my responsibility, even if my brother or BIL are the ones ahhh....using it. That also is what it is.

There is no money in the budget as far as I`m concerned, in the last couple of years I`ve become divorced after a lengthy court battle($) and also experienced about a $25k annual reduction in salary as the corporate bean counters attempt to get my job done without me. Now that`s a long story!......But I still have a ten year old boy who is anxious to get out fishing.

So the bottom line is that a good friend of mine has offered me a Goodwrench crate engine in perfect condition with only 30K miles on it for free. It`s a truck engine if that makes any difference?

Another friend, who is a certified Mercruiser mechanic, says that this engine is a drop and swap without even looking at it. He says that even the cam is the same. He also said that I should replace the gimbal bearing at this time to save going back in later, but he also lead me to believe that this can be done with no special tools. From the little bit of research that I`ve done on the net that doesn`t seem to be true, so now I`m questioning his opinion regarding the direct compatibility of these engines down to and including the camshaft. Would anyone, especially a certified Tech care to offer an educated opinion? Is there anything else I should know or look at?

Sorry for the longwinded post but I want to be clear in the info that I`m conveying and to also reinforce that new marine engines are simply not an option.

Thanks!

Russ"

I have similiar situation and

I have similiar situation and would like to hear from some one that is an expert. A local marina told me that vehicle engines run at slower rpm's at cruising speed (55mph) than boats do and if I put an engine from a vehicle in a boat it would only last 2 or 3 years. If you find out anything please share and I will do the same.

"Will do Dennis. I think that

"Will do Dennis. I think that the guy from the local marina was misleading you to be honest, but to be fair he may not know any better.

The block, rotating, and recriprocating components with the likely exception of the camshaft are the same. The head gasket and freezeplugs are also different materials but I don`t see this as an issue if you are running in freshwater, as I am, in fact I know several guys who have re-cammed automotive "crate" engines for use in their boats with no problems after several years. The cam profile is very important though, it needs to produce power at a low rpm while also making good midrange and higher than normal automotive rpms, say 4600 - 4800.

I guess that you`ve probably also noticed that no legitimate techs want to touch this post with a ten foot poll, huh?"

"Your right about the techs no

"Your right about the techs not wanting to touch this one. I read a post where some one recommended buying a long block. Sorry, $4000-4500 is not in my budget and that is more than the boat is worth. The engine I have is bored .30 over so it will have more power, but the cam does concern me."

"cam profile could be found wi

"cam profile could be found with more info on current engine. no clue on the truck motor. freeze plugs, head gaskets, water pump, would not live in my world. (salt water)if you treat it as a long block, and change over all accs. and thermo housing, etc. it will run. might not have the same power curve, but it's free, and it's your boat to do with as you wish. good luck. S."

"I`d like to not have to chang

"I`d like to not have to change the cam, lifters, bearings, etc but I will before the engine goes in the boat. I can`t see why I couldn`t use the cam I currently have(in boat) but even if I can`t, A new Mercruiser cam is about $200 on-line, add new bearings and lifters and I should be out of that for less than $300?

This boat will never see salt water but changing out freeze plugs to brass isn`t a big deal, nor is changing the head gaskets if a guy were to worry about that, it`s the cam profile that I wonder about, I haven`t been able to find any info, good, bad, or indifferent about a marine cam versus a stock truck cam."

"I am looking to by a 28 foot

"I am looking to by a 28 foot carver with twin 4.3L engines and that would be some good info to know. why is everyone on this site with soo much knowledge not responding???? is this a sore subject or something?? someone has to know something"

""why is everyone on this

""why is everyone on this site with soo much knowledge not responding???? is this a sore subject or something?? someone has to know something"

Agreed John, does seem a little unusual given the apparent activity on this site that none of the resident experts has weighed in on this topic.

Gotta love those Carver boats! I nearly bought one myself but then realized that the divorce was the better option in my case, LOL!"

"RussC, I would not use the ca

"RussC, I would not use the cam and etc from your motor you have now. I worked in an auto garage just after high school(years ago)and I do know that if you have to tear the motor down you are better off using new parts because off wear and tear."

"The folks with the answers te

"The folks with the answers tend to steer clear of these posts because it's like asking them if you can make a Ferrari out of a roll of duct tape and chewing gum.
There are differences in the engines, the most significant have already been mentioned.

If the question is "Can it be done?", the answer is most definately "yes".

If the question is "Can it be done effectively, reliably (i.e., safely), and in the long run more cost effective?", the answer takes on a whole new realm of complexity with more variables to consider than you'd have during a Space Shuttle mission.

I won't answer the second part because more often than not the safe, conservative answer, based on technical merit, is not the answer folks want to hear.

The cheapest part of owning a boat is buying it. Sorry if this doesn't put a fishing pole in the hands of the 10 year old... perhaps he can have as much fun in something more affordable and less likely to cost him his life."

"Thanks Troy. I for one see t

"Thanks Troy. I for one see this same question brought up continuously. Some say it works and some say it won't. If you want to do it, do it but you are on your own.

When the marine engine builders respond to the issue they continually state that the marine cam is the most important part since it controls the valves open/close durations which produces the required torque/HP for marine applications. Enough said."

"Well put Troy<[img]"http://ww

"Well put Troy
Kurt.

If you must use your old cam be sure to index all
parts to include lifters, push rods, Rockers, and hardware."

"Finally! Signs of life from p

"Finally! Signs of life from posters other than those who need the information.

So Troy, since you seem to be the most outspoken of the recent three and the other two obviously are standing behind you, as well as you`ve issued the most dire warning,"less likely to cost him his life", I`m going to focus my questions at you if you don`t mind, but first, I want to remind you that I have asked what are the differences between a marine 4.3 liter and an automotive 4.3 liter, not "will it work?" or "will it make my Chevy perform like a Ferrari?". OK, are we on the same page then? Thanks!

So I already know that the cam is likely to be an issue, I stated that in my first post, and obviously the marine carb as provided by Mercruiser is different than what came OEM on the 4.3s in trucks, but I also still have a good marine(fire and vapor suppressed) carb so I consider that a non-issue. I also don`t use duct tape on anything or consider chewing gum a viable adhesive but I will re-use parts and components that are known to be good. Let`s face it, every machine in the world including the sub in your avatar runs on used parts as soon as it`s been put in service.

You have mentioned that there are differences in the engines, the most significant of which have been mentioned, what are the other differences? How insignificant are they?

Can it be done? We both know that it can. "Can it be done effectively, reliably (i.e., safely), and in the long run more cost effective?", I think that your confusing the issue, no offense intended, let me explain.

Installing the long or short block assembled into a marine long block using my components will be no more difficult or complex than installing a new out of the wrapper Mercruiser long/short block, why would it be? I would have to replace/swap the camshaft and bearings but know from experience that isn`t a big deal. Externally the engines are physically the same. Is there something internal that I should know about?

Second, "Can it be done.......reliably (i.e., safely)".

Why couldn`t it be? What would make the short block that started life as an automotive engine inherently less safe than a marine short block?

You are coupling reliability with safety, which although they do have some relationship, certainly aren`t inextricable from one another. To say that they are would imply that marine engines never fail. We all know better.

But if the crank, piston rods, oil pump, engine block, timing gears and chain, etc are the same components, what am I missing? It`s not like the auto block is any lighter or made of aluminum with no bore liners or something, it`s not like the marine engine has 4 bolt journal caps and the auto engine has two bolt caps, although that is a somewhat dubious measure of an engines durability until we get into some serious horsepower. I`m aksing you Troy, point blank, what are these differences and "variables" to which you allude?

BTW, I have had all sorts of technical and scientific training just like you have if I am to assume that you are a nuke, as your avatar leads me to believe. Lay those space launch variables on me and let me nuke `em out, but don`t expect me to believe that auto blocks aren`t safe when used in a marine applications without backing up your statements with some credible proof. This is exactly why I started this thread. Too many people claim to know something but don`t, and the marine dealers and manufacturers won`t tell you anything as a means of market control. I`m sorry Troy, I`m not stating or alluding that you don`t know what you`re talking about, just don`t be so stingy with the details.

Can I install an auto engine with a marine cam and auxliaries(re-use mine) more cost effeciently than a marine engine? I think I can do it for several thousand less than the prices I`m seeing quoted on this forum. Please educate me as to why I can`t

Thanks

One last thing for now Troy. This statement, "less likely to cost him his life", are you stating that using rotating or reciprocating mechanical components from an auto engine is inherently more dangerous than using similar marine components or are you saying that boating is inherently dangerous so my son would be safer to just stay ashore?"

""If you want to do it, do

""If you want to do it, do it but you are on your own."

Guy, are you offering me a warranty if I use a marine short block? I thought that I was on my own already, thanks."

"Yes it can be done with great

"Yes it can be done with great success, but I surely would change the cam as the truck was
TBI fuel system and those cams are very different
than the marine counterpart. after all, havn't you noticed all the speed boats using gm performance crate engines ETC., and after market parts, I.E. blowers,intakes, headers, and valve train parts.
My buddy and I had recently put a buick stage 1 455 in his glastron to a berkley jet, and that boat hauls ars. Has been for four years, and it's scary fast and emits 100+ foot roosters. Each for his own I say. I am considering a ram jet 502 for my boat, mated to a bravo drive. hopefully soon.
Kurt"

"Cam, Head gaskets and Freeze

"Cam, Head gaskets and Freeze plugs are the only difference.
Sometimes you have to think outside the box to get ahead in life.
happy boating."

"from what I hear, GM target m

"from what I hear, GM target motor div. makes the lb's for merc. with only minor changes as stated above. I think it's propriatory mostly for name sake.
Kurt"

"If I were you I would do it,

"If I were you I would do it, and maybe call crane's, or Pro comp's tech line and speak with them. these guys deal with boat racing and such.
It mainly (cam selection) depends on operating
rpm range, compression, and how you need it to perform. Yes you want some low end torque but must also make peak hp around 4800 rpm for stock
engine. Sounds fairly simple. give em a call.
Kurt"

""Yes it can be done with

""Yes it can be done with great success, but I surely would change the cam as the truck was
TBI fuel system and those cams are very different
than the marine counterpart. after all, havn't you noticed all the speed boats using gm performance crate engines ETC., and after market parts, I.E. blowers,intakes, headers, and valve train parts."

"I think it's propriatory mostly for name sake."

Thank You Kurt, I have noticed."

""Cam, Head gaskets and Fr

""Cam, Head gaskets and Freeze plugs are the only difference.
Sometimes you have to think outside the box to get ahead in life.
happy boating."

Thank You "Guest", I am accustomed to thinking outside the box and that`s what got me on this path in the first place, as you can see. The cash crunch I`m feeling now is only temporary, I`ll be right side up again probably sometime next year but I probably still wouldn`t blindly lay down the cash for a new "marine" engine without exploring my options first."

"Kurt,

That`s a great idea

"Kurt,

That`s a great idea about calling a Cam manufacturer, would you recommend one over the other? Last I bought a cam it was an Iskendarian, about 1984. Yeah, I`m getting to be an old fart! "

"I think the reason a lot of g

"I think the reason a lot of guys are steering clear of this thread is because it's like you're demanding answers on a subject where there's a lot of gray area. Troy and Guy, for example, who are very knowledgable, give you their honest opinion, and you come back and insult them. These guys are here on their own time, they're not getting paid for the help and advice their giving out. They've helped many people with all kinds of problems."

I am partial to comp cams myse

I am partial to comp cams myself. use them exsclusivly with no problems and I can't say the same with crane. When I worked at lozano bros racing we usaully used comp.
kurt

"Graham,

If it appears that

"Graham,

If it appears that I`m demanding answers, maybe I`m being firm in that I don`t want the recycled opinions of the recently "forum educated". I`m sorry that you find that offensive, the last thing I want to do is offend anyone, even those who are webspurts, but I can and have read the archives just like they have, and I can honestly quantify my ability to comprehend while I don`t know any of the posters from Adam or their abilities with the exception of the snapshots of themselves that they have presented with their recent, sometimes amatuerish questions. Why then would I want to hear their opinion that I can`t do what I`m thinking about, even though I didn`t ask them that question? I also don`t want to hear their opinions if all they have to offer is negativity, plain and simple. I asked for factual differences and IMO there is no gray area in fact.

Regarding Troy, yeah, I called him out. He doesn`t know me or anything about my ability, knowledge, or experience but he had no problems telling me that there are too many complex variables for me to comprehend. Bottom line is that I`m not sure that Troy isn`t just standing behind off the cuff generalities and maybe doesn`t know himself. I say prove it. What`s wrong with that? What good is a forum purportedly for the dissemination of fact and experience if the "experts" don`t disseminate?

Guy? Yeah I flicked his nuts and maybe I shouldn`t have, but he did answer my question with a statement saying that he sees this question all the time and then answered the question that he`s thinking of, not the one that I asked. Guy did provide good info on the cam, but his "enough said" statement is akin to saying "I`m smarter than you so you`d better be quiet". My attitude is that if someone is going to attempt to subdue or subjugate me by playing the intelligence card, they`d better have a royal flush because I`m not buying into that. I don`t play that hand against anyone else either, most people as a rule aren`t stupid, so if someone presents what I consider a really half baked opinion I usually try to flesh out and understand their opinion, I don`t say "enough said" unless I`m deliberately breaking balls.

Truthfully Graham, I feel that many of the experts didn`t respond to this thread because they have personal financial interest at stake. I`ve been contacted off the open forum by guys who have shared a similar opinion. This whole veil of secrecy has got me thinking that I need to do a component by component tear down expose and illustrate my findings on the web, wouldn`t that put a twist in the knickers of the guys who aren`t being forthcoming because of the money they are making by selling "marine" engines. My motto is help a guy out when he is in need and you`ve made an ally, turn a cold shoulder to him and you don`t know where he stands."

"Thanks again for the advice K

"Thanks again for the advice Kurt, I`ll give Pro Comp a call, already been checking out the Crane site."

"Russ, First thing you should

"Russ, First thing you should do is tear down you cracked block engine.You may have a bad intake manifold, you may have a bad head, or you may have a cracked block.
"This whole veil of secrecy has got me thinking that I need to do a component by component tear down expose and illustrate my findings on the web, wouldn`t that put a twist in the knickers of the guys who aren`t being forthcoming because of the money they are making by selling "marine" engines."
Once you do this component by component tear down , you will find alot of differences. pay special attention to valve springs , head squinch(cc's),head gaskets, piston compresion, Block core drift, crank windage tray, cam specks are the most talked about.
Marine engines are under a load always,(no down hill runs on the water).
By the way there are 4 different generations of the 4.3 v6. which gen are you using?
get the truck engine and between the two you could build an engine that will work. I think that is all you want to hear anyway.

/as a side note, I can see why you got a divorce,
because you my friend can never be wrong."

"Pretty good post with info &#

"Pretty good post with info "Me", Thank You. You`re right, this is exactly what I want to hear, what are the differences.

Was I wrong for wanting straight, factual answers? I don`t think so. I thought I was wrong once but..........well, you know the rest.

HAHAHAHA!

What generation 4.3 am I using? I have no idea, the Mercruiser tech said they are the same engines, see any of my point?

Thanks again Me, at least you have offered me some areas for consideration."

"good luck with your science p

"good luck with your science project, we're all on the edge of our seats!"

"E-mail me your phone number G

"E-mail me your phone number Graham, you`ll be the first to know how it turns out!

<font size=""+2"">HAHAHAHAHA!!</font>

Thanks for your well wishes."

"yes please let us know if you

"yes please let us know if you do a part bye part breakdown and please post your findings. It would be a BIG help in my consideration for purchasing the carver"