6.2l won't go faster than 45mph.

[19ft freedom]

I bought a 19' freedom that has a 6.2l in it! I have a buddy that has the same motor in a 25' Nordic, and his boat goes 65! It had bad lifters in it so i had a new cam and lifters put in with a slightly bigger cam... a 370hp cam. it still only goes 45. I have changed all the tune up parts and set the timing. Even changed the fuel seperator! This is the first boat i have owned. Does any body know what else i could check to see what is wrong?? thanks in advance!!

 

[steelespike]

Re: 6.2l won't go faster than 45mph.

How's the compression?Is the bottom clean?Is the bottom true;no distortions.
especially just ahead of the transom.What size and type prop are you running? aluminum or stainless?is it in good shape?What is the max rpm at max speed?What is the max rated rpm of the motor?Is the speed by GPS? is the 65 by GPS?A cam change without carb and/or manifold changes could be ineffective.Has the hull or flotation foam absorbed water?You may want to weigh it and compare to that listed in the NADA listings?
All cylinders working?Sometimes an 8 cylinder can be missing on one cylinder and not be noticed except for performance.Don't assume.We have had a number of new setups and refurbed here missing a cylinder.

 

[19ft freedom]

Re: 6.2l won't go faster than 45mph.

yeah, the 65 was by GPS. The compression was 140 in 7 of the cylinders, the other one was 135, so thats ok. The bottom of the boat looks good, no dings or blemishes. The engine cover says it should run between i think it was 4200-4600 rpm. It runs between 3800 and 4000 rpm. It came with a 21 stainless prop. So I talked to a prop shop and he sold me an aluminum 19 to see if the rpm's would be where they should be. It did increase them about 2-300 rpm. Wich also helped it get out of the water a little better. I like the idea of weighing it and comparing it! It does seem a little heavy! It takes for ever to get on a plane, even with the 19 prop!... if it is water logged. What can i do to help or eliminate that?

 

[ne7800]

Re: 6.2l won't go faster than 45mph.

if its water logged you have to pull the floor remove the foam not sure if you have to reinstall the foam install new floor glass it in and put your interior back in

 

[steelespike]

Re: 6.2l won't go faster than 45mph.

I would think that combination would twist a 23 or 25" pitch easily.
25" might not be ideal all around but it should manage with it.
I don't think water logged foam would suck up 20 mph.Might make sluggish hole shot but something else is going on.I would prove all cylinders are working.Dissconnect one plug wire at a time and ground it.See how it affects performance.If you have a valve floating or plug breaking down it should show up.

 

[19ft freedom]

Re: 6.2l won't go faster than 45mph.

Yeah, I don't think it would lose 20mph either! It does have a problem getting out of the water when i have four adults in it. I have to put the trim tabs all the way down and the drive. If not it won't plane out.... I did check the spark. Every thing checked out ok. I even put new plugs in just in case. Also when I had the cam put in, I had new valve spring installed to. I too thought it could be the valves floating. I was wondering if maybe the carb isn't opening up all the way? That was gonna be my next check. What do you think?? I really don't want to cut up the floor on a boat I just bought... But I guess if I have to I will.... At a last resort!! Again, Thanks for the help and suggestions!!

 

[Randybeall]

Re: 6.2l won't go faster than 45mph.

Lets discuss what you have put in the engine. Was the cam and lifter setup you purchased for a marine application? If not you will not be happy. Marine engines do not perform like an automotive application. Check with any of the major performance cam people to certify this. Marine applications must have more torque, not high rpm horsepower. The correct cam will allow the engine to breathe fully at the rpm range which we must work in. In a car you can change gears to let the engine rev up and get to the higer horsepower, only one choice in a boat. The other bad news is that if you reprop to get the high rpm you need to rebuild the lower end of the engine with parts built to stand the additional rpm and power.

 

[Dhadley]

Re: 6.2l won't go faster than 45mph.

Don't forget hull design. You're comparing apples & oranges.

 

[steelespike]

Re: 6.2l won't go faster than 45mph.

Without knowing the year of the boat can't tell the weight.It does appear
the 19s are about 2,200 lbs though there are some that are about 1800.
It could be a little heavier with a 6.2.You could weigh it before tearing up the floor.While on the trailer check the bottom for any distortion.Usually hollow spots near the transom.Could keep the bow from raising correctly.Check the carb see if it opens all the way Perhaps the timing advance isn't working right.
Check any rubber exhaust connections that aren't restricted or collapseing
in operation.Something is screwy if you have trouble planing.
You might pull the plug wires one at a time at idle.Maybe a bad wire, sticking valve.Do the plugs all appear normal.Non black,wet or extremely clean?

 

[19ft freedom]

Re: 6.2l won't go faster than 45mph.

The guy that did the cam told me the cam was a 370 horse mercruiser grind? So I'm assuming it was a marine app. The rpm range hasn't changed much. It's still not turning the R's it say's it should. so the bottom end should be ok. if i do get it to spin up higher, then I will reprop it to keep it in the proper range. From what my friend told me with the other boat is that they had a 330hp, and a 370 hp 6.2?? The year of my boat is '91. It is pretty wide! I heard the hull design could be a problem too, But i wouldn't think it would cause it to bo so guttless out of the hole? Good idea on the wires! Thats probably the only thing tune up wise i haven't replaced. I will definatley get some new ones. My next check will be to see if the carb is opening up all the way. As far as the timing, If it wasn't advancing, wouldn't it ping on acceleration, or under heavy load?... one other thing someone told me is that there are different gear ratio's in the drive. Is that true and if so could that be a problem?

 

[Randybeall]

Re: 6.2l won't go faster than 45mph.

You can almost never hear ping in a boat engine, to the point of blowing holes in pistons. Can't begin to tell you how many engines have been ruined by some body advancing the timing just a little more because it is not pinging. If it is a mercruiser cam that is most likely good. Throttle, plug wires, fuel flow, go through the whole list like everyone has suggested. No magic bullets on this one.

 

[19ft freedom]

Re: 6.2l won't go faster than 45mph.

yeah, to listen for the pinging, i had the engine cover off and crouched down next to it while my brither went full throttle. It seemed ok. but I think i'll play it safe and put a light to it! when it comes to the carb. I think it's a Q-jet. Someone told me that those have some kind of pump rod that sticks sometimes. Ever heard of something like that?

 

[Silvertip]

Re: 6.2l won't go faster than 45mph.

Sounds to me like you are shotgunning this engine/boat and are not really doing the simple things first. Did this engine EVER run correctly -- as in before the work was done on it? Check the outdrive gear ratio and verify it is correct for this application. Yes - check to make sure the throttle is opening fully. And understand that the secondaries on a Q-jet are "air valve" secondaries so the air valves will not be open even though the throttle is wide open. How much experience does the dude have that installed the cam. It could be the cam timing is way off or that the cam he told you he installed is not really the cam that was actually installed. Was the cam properly broken it after installation. Is ignition timing correct -- and no, retarded timing does not cause ping or detonation. Timing too far advanced for the grade of fuel being used causes that. Timing that is not advancing properly will not generally cause poor hole shot since the engine is not running fast enough to begin advancing. Advance is needed at higher rpm. Do you have restrictions in the exhaust manifolds? Many people cannot tell when an engine is missing so verify that the firing order is correct and that the engine is actually firing on all cylinders. Restricted fuel flow can cause the engine to labor. Check fuel flow and pressure. Just because pressure is good does not mean the flow rate is normal. You can get the same pressure through a hypodermic needle as you can a fire hose but guess which will flow more fuel.

 

[19ft freedom]

Re: 6.2l won't go faster than 45mph.

Well whe i tested the boat boat before I bought it. it had water in the gas, so I didn't really get on it. Then after I drained the gas and the fuel seperator, It didn't sound right. It sounded like it was missing. So I did a complete tune up, minus wires, which i'm gonna replace now! But it still sounded funny. So I did a compression test and found erratic compression in one cylnder. I was thinking broken valve spring. I took it it in and they found a bad lifter. So I had a guy put cam, lifters, and springs to cover it all. As far as if the cam he put in is what he said, I never did get any paper work showing specs. So I guess there is the possibility that he lied to me! I hope not! I think i'll be asking him for that! The guy that has done the work owns his own shop, and deals with both boat and automotive issues. He has experience doing engines, so I would think he broke the cam in right!... I hope anyway!

So I think I'm going to first check that the carb is opening all the way. If it is, then I'll check the fuel pressure. If all checks out there then I'll put a timming light to it to see if it's advancing properly! I don't think the Exhaust is restricted because when it's running the water comes out in a nice spray, and both sides look the same as far as water flow coming out..... P.S. I'm an idiot! it's not a 6.2, It's a 7.4!! A 454 big block!... Even more reason it should go faster than 45!