My first marine eng rebuild (need advice)

[Kaos1]

Hi everyone. I just bought a project boat about one month ago and the first order of business was to snatch the power plant out and rebuild. I just got it back from the machine shop today and I am getting ready to start assy soon. It is a small block chevy (5.7), .040" over, with flat top pistons. I have not been envolved in any marine engine rebuilds so any marine spacific advice would be greatly appreciated!
PS. I did research the inversion issue and I think I have the cam question covered but like I said any advice would be greatly appreciated.
Thanks,
Travis

[EXTREMEBOATS]

Just a few questions first. Did your machine shop know its a marine engine? Why? clearence are different then automotive. Now give a general discription of what your building it for, heads,intake, carb, ignition,exsaust ect... Then we can help dial in your needs.
Mike :eek:

[SmokinLowriderSS]

Clearances in general need to be a few thousanths looser in a marine engine because they are worked harder and swell more unevenly from more uneven heating. Just toward the wider side of bearing tolerances (but not out of spec), a few extra thou on ring end-gap (toward the wider end of spec(mid range OK, just don't file to minimum) to insure they don't close & bind (ripping the piston top off) pretty much covers the greatest risks I can think of off the top of my head.

[Kaos1]

I did tell him that it was a marine engine. He said that my crank had appeared to be already turned like a race engine (I now know why). Anyway, He just polished the crank. I have not ordered the bearings yet because I am still doing homework. He recommended +.001" but I am glad you guys decided to reply. If I understand correctly that is not what I need to do. I will order standard bearings so that it will be on the loose side of the tols.
As far as what I am doing with the motor. It was a 210hp mercruiser stock. Had a 2bbl mercarb etc. I am just giving it a little more grunt, nothing drastic. I had the heads redone stock, I'm upgrading to a 4bbl carb, a beafier cam (Crane power master) I can post the specs if needed, .040" over flat top pistons, and thats about the extent of it for now. I really appreciate the help and welcome all advice!
Thanks again,
Travis

[SmokinLowriderSS]

Don't know what compression you are running (head casting #'s can be looked up) but if you are already buying pistons, I would buy something that will get you arround 9.5:1 compression. Lots of grunt improvement there compared to 8.?:1.
Doesn't have to be exotic and I was just today looking at some Speed-Pro Forged for $40 each. (time for everybody to slam on these now haha) in my Jeggs catologue. Might not be greatest thing for a blowermotor but I'll wager they beat out Hyper's for "regular" uses. (OK, so what doesn't?) :D

[EXTREMEBOATS]

Nothing wrong with that... Use em all the time in rebuilds and never had a problem. Go with a RV type cam, more bottom and mid range. Stay easy on the rest and should be a relieable engine. BTW those castings when used with a four valve relief flat top get around 9.8:-1 comp at .015 piston depth at TDC. Using a Felpro "Perma Toruqe" gasket. And breath good up to 5000 rpm. :D
Mike

[SmokinLowriderSS]

I'm running a "jet boat special" from DuaneHTP and am really happy with it in my 454. .565" lift, 280 deg duration, hydraulic, idles stabilly (albeit lopey) and pulls hard from idle all theway to 4,700 where the pump stops her (till nitrous pushes her to 5K.) Entire kit set me back $400, Iskendarian cam, Isky Superlifters, springs, new steel retainers, shims, polylocks.

[Kaos1]

The cam that Crane recommended for mine was
Power master: 2000-5000 rpm - 272/284 adv dur - 216/228 @ .050 - 112 deg lobe sep - .454/.480 lift.
They also have a energizer with similar specs they said would work but the energizer is not a dual pattern cam.

[steelcomp]

Skids are for kids. :D j/k...sorry...had to say that.
Good cam for what you're doing. Sounds like you're on the right path. You might keep an eye on the clearance between the bottom of the retainer and the top of the guide on those exhaust. Just a good idea to check. Make sure to include your stem seal...it's liable to get crushed.
Cyl clearances need a few of extra thou because in a boat, unless you have an enclosed cooling syst., the motor will always see cold water, but the piston will see a little extra heat due to more constant load. You get a "cold cyl, hot piston" syndrome, where the cyl dosen't grow as it would in a car, and the piston grows more. I wouldn't even bother with "file-to-fit" rings for this motor. Waste of time. Pre-gapped rings will have more than adequate gap. Those are good durable pistons that should give you years of service. Definately have the motor balanced, too.

[Kevin Heine]

What kind of boat is it? Jet, I/O, V-drive?????????

[396_WAYS_TO_SPIT]

clearances.........
.0020-.0025 rods
.0025-.003 mains

[396_WAYS_TO_SPIT]

What kind of boat is it? Jet, I/O, V-drive?????????
good question

[Kaos1]

It's an I/O.

[Kevin Heine]

Huey,
Not sure how much knowledge you have in this area. All mine was from the street. Not gonna consider myself a " guru" by any means. Be cautious when building the motor. The water is completely different than the street. I'd be a little concernmed about the cam you mentioned. Keep in mind you don't have a torque convertor that slips to allow the motor to reach the power curve. I'd look for a cam that has a power curve from idle. With this cam coming in at 2000 this thing is gonna be a pain to get on plane. You could advance the cam to bring the power curve down, but you'll lose upper RPM. When building a motor for the water remember TORQUE, build low end and prop up. JMO

[Kaos1]

Cool. I will do some more research on the cam. That is the one that the tech at Crane recommended but I will look around some more before I buy. Thanks for all the info!!! You guys are helping a lot!

[Kevin Heine]

I talked to several "techs" from Crane,. comp., Isky. I was not impressed with them at all. All they could do was read me what was in the catalog. Same thing I could do myself. And, they all said the factory cam was the best for my application. I knew that was B.S. I had the man who did my heads get the cam for me. It was a special grind and cost me an extra 20 bucks. Talk to the machine shop that did your work. Tell them what your trying to do. And have them get you the right cam. Remeber something very very torqueeee. Yeah, your gonna have pay a little more for it but its money well spent. Something else, are you going through transom exhaust". They say keep the lobe seperation 110 or above because of reversion. Mines a lot less than that and have been runnig the guts out of it for 2 summers.

[steelcomp]

If you really want the right cam for what you're doing, contact CStraub here on the boards. He'll set you up with exactly the right grind.

[SmokinLowriderSS]

That cam is very similar to the "Chevy High-Lift Hydraulic" that came OUT of my 454 when I put my new Iskendarian cam in. :
Original cam .......... hydraulic
.282" exhaust lift (at lobe)
.271 intake lift (at lobe)
.480" lift (valve)
.461" lift (valve)
Duration, 268* In / 274* ex.
Chevy 3883986 High-lift Hydraulic
Used in L-71 / L-72 / L-78 / LS-5 engines
It's a hard puller right from bottom. I don't think you'll have trouble with lower-end torque, especially in a 454.

[SmokinLowriderSS]

I'm not so certain a dual grind cam is alll that much, or there'd be more of them I'd think.
Course, that's another thread-load of opinions there. :D

[Kaos1]

I talked to several "techs" from Crane,. comp., Isky. I was not impressed with them at all. All they could do was read me what was in the catalog. Same thing I could do myself. And, they all said the factory cam was the best for my application. I knew that was B.S. I had the man who did my heads get the cam for me. It was a special grind and cost me an extra 20 bucks. Talk to the machine shop that did your work. Tell them what your trying to do. And have them get you the right cam. Remeber something very very torqueeee. Yeah, your gonna have pay a little more for it but its money well spent. Something else, are you going through transom exhaust". They say keep the lobe seperation 110 or above because of reversion. Mines a lot less than that and have been runnig the guts out of it for 2 summers.
I do not remember the guys name that I talked to but he was quick to recommend that cam when I told him it was going in a boat motor. He also said I needed atleast 112 deg lobe sep. So far all the cams I have found that have a lower rpm range seem to be close to stock. As far as the exaust, I am looking into going through the transome. Thats what I would like to do. In fact I have a post in the outdrive tech section about that. It is the thread about open exaust question http://www2.***boat.com/forums/showthread.php?t=89048. I am trying to find out exactly what I need and how to do it.