Need advice on engine Decision

[BryanF]

Hello All, <br /><br />I was hoping you guys could guide me in the “best direction” on how to handle the inboard motor on my 24’ 69 Thunderbird. <br />Since this is my 1st boat, I’ve been looking into rebuilding or replacing everything starting with the motor. I currently have a GM inline 6, 250 cid, 160hp. It has not been run in 5 years. (Was winterized, 5 YEARS ago!) I ‘m pretty sure it is the original engine. Has it been rebuilt…???.<br />Replacement Cost for this engine seems to be around $1250.<br />Another option is an “inline 6, 292cid, 200hp” cost is about $2250.<br />Is it worth the extra $1000 for 40hp more and more gas consumption? <br />What would be the difference in mph in these motors? (Like it matters being the 1st boat I’ll have ever captained…lol) But just for an FYI.<br /><br />Thanks,<br />Bryan

 

[GodsBeast]

Re: Need advice on engine Decision

Hello BryanF, I am not a boat mechanic and won't pretend to be. I watched your question move down the list and waited for someone with more knowledge to reply. I'm Taking into consideration that these two motors your talking about, may be the only ones that will bolt into place without a lot of other alterations, and your trying to make a decision just between the two of them. This is how I would approach the decision. $1000.00 for 40 horses depends on the situation your in at the time. Your question may be answered by another question. Can you see yourself in the future, trying to accomplish something, saying Man I wish I would have spent the extra $1000.00 for that extra Horsepower? <br /><br /> I struggled when buying my boat between the 4.3, the 5.0 or the 5.7. I knew that somewhere down the road, I was going to be upset with myself for not getting what I wanted in the beginning. I bought the 5.7. <br /><br />YOU are the one that has to live with the DECISION that you make, and be happy with it. <br /><br />I'm sorry I don't know more about those two types of engines and the differences in their fuel economy. But generally, my way of thinking, if your not always running WOT, the bigger engine, should not be that much worse, and may be better, at the same cruising speed, in the same boat. Plus knowing you have some in Reserve, just for those times you want it, can be a nice comfort.<br /><br />I wish you well on your decision, and hopefully someone else with more knowledge of these two engine's will reply, to help you with this decision. <br /><br />Just one of GodsBeast's

 

[airman]

Re: Need advice on engine Decision

Because it's not my $, it's easy to say spend the extra and get the bigger motor but that's my inclination, assuming thst the boat is rated for it. Unless you cruise faster I don't think your mileage will go down much and the engine will like it better too. I would suggest at least trying to start the old engine first though. I pulled my old 470 back into service after sitting for 3 years and went for a run a month ago. It ran perfectly. If you can do this it might tell you a few things before you go spending a lot of $.

 

[andrewgroup]

Re: Need advice on engine Decision

The GM In-Line six is and was such a durable engine. In the early 70's I rebuilt several of them for street rods, getting maximum HP using hop-up kits from Clifford Research.<br /><br />What I would do in your case is:<br /><br />remove the spark plugs, pour some a TBLS of engine oil into each cylinder and manually crank the engine using long wrench on the balancer on the front of the engine. If it moves easily by hand, I would then proceed to see if the starter will crank it over......If so I would get a compression check on each cylinder.....If this looks good, I would see if you can get the engine to fire first on starter fluid (shoot first, crank second)<br /><br />Does this have an external seawater pickup, common on IO in 69...Does this have a bronze seawater pump mounted in a bracket on the lower starboard side of engine?<br /><br />If so, I can show you how to make a low cost equivalent of the earmuffs for the pickup.<br /><br />Anyway, you might find that this engine will start and run just fine...

 

[Ralph 123]

Re: Need advice on engine Decision

Certainly worth the time to figure out its condition unless you have some other compelling reason to get a new engine. I know plenty of people who are worry warts and would be afraid of the boat with the old engine. I was in that camp with my 79 Formula so I put in 2 remanufactured engines.<br /><br />Anyway, just remember the old saying that there is no replacement for displacement. You'd hate to go through a repower and then wish you went with the bigger engine. If you can afford it, and want to replace regardless, go with the bigger engine. If you are on a budget, etc, try to repair what you have and/or go with the least expensive solution.<br /><br />Also, you may not be stuck with a 6. You may have room for an 8 for the same price. Due to the shear volume, 350 V8s are abundent and cheap. You would need to regear or replace your outdrive though.<br /><br />Check out: http://www.1800runsnew.com/ <br /><br />To get a sense of what is available and prices.

 

[BryanF]

Re: Need advice on engine Decision

Thank you for the responce Guys, I've been away for a few days.<br /><br />GodsBeast,<br />I am looking to keep this as much as possible a "drop in replacement". After I get "sealegs" and the hang of boating... I can see myself wanting "more HP" Thank you for the "? with a ?" It actually CAN be an answer <br /><br />airman,<br />Thats a problem i have... Spending the "Extra" ... NO problem with it at ALL! <br />Money's not a "terrible" issue if its better spent! I thought about getting the existing motor running but then thought about the age and condition(???)and $$$ spent that would be spent... maybe it would just be easier to just install a completely new engine. I do plan on keeping this a LONG time! <br /><br />Andrew T. <br />Great Info!!! Thank you! I'm learning as i go here, So I do not know if it has a external seawater pickup... Never even heard of one till YOUR post. Will have to check into that tomarrow.<br /><br />Ralph Spencer <br />Yes, you could say I'm a bit of a worry wort about this... Never been on a boat before and DEFINATLY want to do what i can to prevent any "preventable" problems Love the "No replacement for displacement".<br /><br />Could someone give me an idea of what kind of speed we are talking between the two engines?<br />Thanks, <br />Bryan