Need help with cam,intake and carb.

[COOL CROSSBOW]

Hi guys I am rebuilding some 02 502s for a friends 87 CROSSBOW. I would love to do it like 33 CROSSBOW did but he he isnt as big of a hot rod as i am. So im thinking just a mild cam like the crane 741, replace the nonadjustable rocker arms and go with an RPM air gap intake and Speed demon 850 carbs.

Or would it be more cost per hourse power to put 177 blowers on them?

I have been reading as much as i can on marine engines but there are somethings i dont understand just yet. I see all hopped up engines running X stile manifolds such as Dart Motown single plane. But my under standing is boat motors need to make more torque cause these boats are so heavy
thats why i was thinking the air gap or blower. I would like to hear from you performance guys so i dont mess this up. Its not like building 9sec, camaro motor. Oh yea i have learned to hang from my toes and turn wrenches now and have a strong magnet on a long string for those dang slippery bolts LOL.

[SilverBack]

Marine engines are not anything like car engines or any other kind of engine for that matter. People told me that when I started and it is easy to just dismiss it but you do so at your own peril.

It seems like there are 2 ways to go that are are best. Bigger cubic inches or a blower.

If you are buying crank kits you could stroke the engines to 540 and that makes a lot of difference. If you do that the 741 cam might be ok. Don't put that big of a cam and a 850 demon on a stock 502 boat motors.

The other way is a cam. There are a lot of Procharged engines here on this website. I think that Whipple is the best blower that you can go with overall. If they are 2002 502 MAGs they should have fuel injection and more than likely a MEFI 3 computer. If you want to stay with that setup. I think the procharger or stroking the engines to 540 ci would be the easiest route and get a new calibration for the computer.

Maybe Grizz and Buizilla will chime in. Griz has a carb... procharger setup and has been around the block a few times.

Here is a little advise....when Buizilla talks..LISTEN....He knows his stuff!! If you don't listen very carefully you will be looking back at old post one day kicking yourself in the butt wondering how he nailed everything he said and you didn't listen!!

Good luck!!


BTW...check the stringers and transom out before you do too much..you may need to spend some money elsewhere!!!

[COOL CROSSBOW]

Ok thats good info. These 502s dont have efi they are carbed and the reason i think there 2002 cause of the part number on the heads came out in 02. I think who ever put them in used the 454 intakes and carbs they do have hyd roller cams and nonadjustable rockers.
If the 741 is to big what about 731 i want all my ducks in a row before i start ordering parts.
Ive been reading about marine blowers how they differ from cars I am running a B/M 420 Mega blower on a 454 in a 67 Camaro it has teflon lined roters but marine blowers dont do to the friction the produce in long run time not like cars short bursts. Weve run a Pro Charger on a 69 FireBird with a 455 and oh my the torque that thing makes but there no walk in the park to tune and that brings up a nother question do they make an O2 senser to put in marine manifolds for tuning so for i havnt seen one or how do you check your air/fuel other than reading the sparkplugs.
About the stringers i keep reading about that ill have the engines out comepletly soon and i dont realy know what the stringer is to check. There is a big beam running through the middle of the engines ive been standing on there are some going across the bottem, which one do i check and how do you check it. Im sorry about my dumb questions but i am enjoying this and want to get it right.

[COOL CROSSBOW]

So what im reading about the tuning is that you want to dino tune them wile there out of the boat. I can see that and that way you could tune them on wide band O2 but for the guys that dont have access to those nice tuning toys. Would this be a correct starting point. Set timing at 38 degrees @ 3000 rpms make some wide open passes and check the sparkplugs and jet the carbs accordingly?

[SilverBack]

I am not a mechanic but I have spent a good bit of money with them and I have had all kinds of race engines. Boats are not like anything else that you are use to. I think that 31 degrees plus or minus is more like it but I think you may be headed for a very ruff patch here unless you get with a real boat mechanic or tuner and get some background and details. I think that if you build these things like you are planning you may be in for some tough times. I can tell you that things that normally work don't all the time when it comes to boats. I can tell you to throw desktop dyno and the such out the window when it comes to boats. Good luck and sorry that I can't be of much help!!

[BUIZILLA]

boost + 38* = BIG mess

[COOL CROSSBOW]

boost + 38* = BIG mess
H_ll no i would not do that! Im sorry i was thinking N/A timing when i was asking that question ill try to be more clear. My Buick turbo V6 in my 88 IROC camaro only gets 24 degrees at 25 psi. MY big block is 31 at 13psi but has an MSD boots retard. With out you guys input my car knowlege is all i have to go on. I am a good student and have big ears i will listen very well to what yall say.

[BigGrizzly]

Been there don that. First. If you do it your way you will have a boat that may not be as fast as stock. Carb too big, Adjustable rockers a must, wrong place to go cheap. I personally don't care for that cam. As Buiz said 38 will be bad, and I will add even without the Blower it is NG. My Engine is a 502 Procharged with a carb 825 CFM carb in a box. I run less then 5psi of boost. My engine will break almost any drive trans combo if manhandled. I will not go into the internals of the engine, but to build from scratch it will cost about $33,000 including labor. I am sure someone can do it cheaper. The real clincher is mine is around 800 hours old. The end result is you get what you pay for. I don't mean to sound harsh but doing an engine for a boat is not a cake walk. I have well over 4 hours of dyno time on it just tuning it in with some of the best that there are.

[COOL CROSSBOW]

Wow thats serious, we did find the carb in a box turn out to be the best way to tune that pro charger, carbs are made to be sucked on not blown on and im not saying it cant be done the other way it can, its just less of stressful with a box.

[BigGrizzly]

C Crossbow, Put the books away. IF you blow through a carb not in a box feul goes out every breather and more. In a box everything is then equal. The onlu thing you have to worry is fuel pressure. When we dynoed my engine the Drag racing hall of fame was present. It had a pyrometer and an O2 sensor on each exhaust pipe. we matrix ed the entire engine for hot spots. when it was done the exhaust was within 150 degrees of each other. The O2 would make the EPA smile. Otherwise it was just another dyno run. And the best part it cost me a large Domino's supreme with extra cheese. Speed and horse power is no joke in this shop. I am convinced that correct dynoing is the first key to longevity the next is maintenance and usage(read that abuse). Without the first there life span is shortened.

[COOL CROSSBOW]

Yes your right we found out that the hard way 10 years ago when they first cam out, and ATI was no help eather. I belive they used us the consumer as there test bed in the begening and what we would tell them about what we found on how to tune them they passed on to others as if they knew it. And thats just my 2 cents cause thats the way i felt when i would talk to them back then. I am running the FAST FXI on my turbo car and it has individual cylinder exhaust probes whitch helped alot cause # 3 and 4 are very lean and you would nevery know that with just one O2 in the single exhaust pipe. I know i not the smartest guy but its cool to talk to guys whos been there done that and arnt to egotistical to pass on helpful info. If you dont help the new guy or the little guy you will find your self racing or playing by your self and no customers.

[breeze400]

:bonk:I have to go along with what everyone has said hear allready. Speaking from my own experiance YOU JUST CAN"T BUILD A BOAT MOTOR THE SAME HAS YOU WOULD A CAR!!!! They are two extreamly different animals! My boat has A 460 ford motor in it so I do not have lotts of GM experiance. I can tell you this though! USE MARINE PARTS!!!! DO NOT let yourself think that auto parts will work!! They WON'T!!!! Auto parts are not made to withstand the pounding that A marine part will! Use MARINE CAMS!! Not cames designed for car motors or you will have serious inversion problems! ( Inversion, water being sucked up into the cylenders through the exhaust valves causing hydrolick lock. KA BOOM!!) I have gone through 4 motors thinking that I knew what I was doing cause of my geer head mind. Then I seeked out help from someone who knew marine motors. Now i've got A good one!

Sam.

[COOL CROSSBOW]

Well thats why I am now a member of a this site and fill lucky that it turned out to be a Donzi one they seem to get a little respect when you talk about then. Kind of like Buick Grand Nationals in the automotive world people respect that car when it pulls up cause you cant tell if its stock or runs mid 10s.
Im still trying to get some ideas now that we know what these engines are. Should i try to get the compression up from 8.75 to 9.50, should i run a camshaft with about 10 degree split duration to help keep the inversion down (such as 220 230 or 230 240 @ .050) with a centerline around 112 or 114. Is there amy benefit going with a Performer rpm Airgap over the stock alum high rise? And what style adj, rockers would you suggest converting to, i saw a nice set of Jesels on Horse Powers build.
You guys can PM me your suggestions if you dont want to get hit with a tomato i know what it can be like making suggestions on web sites.

[BUIZILLA]

I raced T Types and GN's with my youngest brother starting in '87ish, I was probably one of the first 8-10 idiots in the country to run low 10's with it... I had one of the first of 6 DFI boxes out that John Meany and Accel designed... drove it everywhere.... even drove it from Miami to Etown and Atco, ran 10.29 for the first Annual Buick/Mustang Shootout, won my pairings, then put the air on, and drove it home.... I had about 60-65 local turbo cars I worked on on nights/weekends... boats are cheap, THAT was an expensive hobby... :nilly: :wrench:

[COOL CROSSBOW]

Expensive shoot everything on a boat is times two LOL.:eek: Love those GNs

[breeze400]

Hear is a link for Comp cans. You can find listings for marine cams hear. take your pick, From MILD to WILD!!! LOL.
Sam.

http://www.compcams.com/DefaultWide.asp

PS YOU CAN ALSO GET TECK HELP THERE HAS TO WHAT CAM WOULD DO WHAT YOUR LOOKING FOR PERFORMANCE WISE!

[breeze400]

Hear is Comp cams phone # You can call them and get the facts from them!

800-999-0853

[BigGrizzly]

I will only do the rockers and that is a brand name roller rockers that is it, mo magic

[COOL CROSSBOW]

I was just joking about thoses JESELs I run Comp Pro Magnums on everything they are hevy but they never brake.

[BigGrizzly]

Quit joking about engine parts. Some guy will go out and buy something because he read it here. I have been bitten myself on a joke I threw out here years ago.

[COOL CROSSBOW]

I think i found the cam that i going to use, its a LUNATI Voodoo cam part#60621 221/229 @ .050 575/575 LSA 112

I guess a nother reason for the NOT INTENDED FOR MARINE USE is these engines are not balanced so should i get them balanced sence there going back in a boat?

Something else i noticed when taking it apart, the rust on alot of places you wouldnt see rust like in the cyl. boar on the roller cam and lifters on the oil splash pan under the intake it was flaking off of it, falling down in the cam vally. Is that a comon thing on a boat engine because they dont get used in the winter?

NO MORE JOKES:frown:

[BUIZILLA]

I think there are better choices than that VooDoo... it doesn't say what the overlap is..

the rust under the belly pan and elsewhere is probably from water in the oil... head gasket? cracked block?

[BigGrizzly]

I know the origin of that cam and I would not use it for that application. As for the balance I would not know because I have not built a non balanced engine in 40 years. That cam will take a little of work down at the bottom end to get it nice.

[BUIZILLA]

I guess a nother reason for the NOT INTENDED FOR MARINE USE is these engines are not balanced so should i get them balanced sence there going back in a boat?
where does it say or imply that?

[COOL CROSSBOW]

When i google the part# i found on the tag on the side of the block it come up biult by PACE PERFORMANCE #12568778 for GM and it says that in the disclamer.
This engine did have a blown headgasket and cracked head all of that got repaird at another shop but still ran hot so he brought it to me.

[BigGrizzly]

Almost every Reman or crate engine has that disclaimer. I explained it is to avoid the CG regs. Also there is also one that states not for highway use. All this BS is so if they get are found on a unit and it doesn't measure up the builder is not liable. If you are a marine shop and have a business license and you put a non approved carbe on it and it gets inspected your the one in trouble. If a fire happens(seen this one at a local dealer) and the insurance agent inspects it he can and now most likely dump it on the installer.

[breeze400]

I've tryed A Lunanti cam on my ford 460. Did not do the trick!:nilly:

[RedDog]

Search the web for a deal on Dennis Moore's book:

Big Block Chevy Marine Performance: Engine Modifications For Maximum Boating Performance
Author: Moore, Dennis
Paperback; Illustrations
216 pages
Published: October 2001
Penguin Putnam Inc USA
ISBN: 1557882975
Dennis Moore, details the differences between automotive and marine performance components and design. Topics covered include: -- The differences between auto and marine engines -- Starters, flywheels, ignition systems, exhaust and cooling -- Parts combinations and recommendations for performance applicationsAlso included are photo/how-to sequences and instructions on build-up and installation as well as tuning and repair.

[BigGrizzly]

That Dennis Moore book is a joke. there is nothing in it worth while. Does any body know who he is.:shocking: The book is run of the mil stuff, read that Engine Building for Dummies. I though we flushed that away Many years ago.
As for comp cams vs Lutani, vs another brand. It is the combination and application I have got junk from both. I once called comp cams and wanted a cam for my Mach1. The tech asked me the specs. I told him. He then told me it was too much compression. I had dropped it 2 points from stock. I said good by and don't call anymore. I buy I just won't talk to them.

[RedDog]

Yes Big Griz, you have probably forgotten more about building a marine engine than I have ever, or will ever, know.

That said, a "marine engine building for dummies" is a valuable source for some one just getting into it - which is where I think Cool Crossbow is. He is an auto guy; the book explains in fair detail the differences from marine. Until someone writes something more current it is the definitive "how to" book out there. If there is a better one I would like to know about it and I will buy it.

[BigGrizzly]

Red Dog, Don't under estimate your self, remember I know you. However C Crossbow is a listen and learn guy, he doesn't sound like a wantabe gas jockey. You notice he never argues his position, he just asks what would be better. He DON"T Need No Stinken book on Ebay:yes:

[COOL CROSSBOW]

Ill try to find a copy of that book you never know i might learn something new.
I did learn something new about these new GM squarport heads, they are much easier to port out than the old 990s. The casting is much cleaner and the bad casting lip under the valves is already machined out for better air flow. It would take HOURS to port out the old heads these took no time.

[COOL CROSSBOW]

BigGrizzly that is a nice shop.

[BUIZILLA]

there is no reason not to buy and read the book..

there is actually some very good basic info in there for the novice to digest.. and filter out

however, having said that, don't take everything you read in there as gospel...

:wink:

[COOL CROSSBOW]

Im not paying $400 for a use basic marine engines book. I found several and all of them are around $380 used so much for that.

[COOL CROSSBOW]

I got in touch with a guy name Bob Madara at Marine Kinetic and he has got me on the right path now. I told him all thats going on and he has made some great sugestions. He also has seen these 502 crate engines with the thin mm rings polish the cylinders with out wearing the boar. Im going to fix that problem too.

[RedDog]

Im not paying $400 for a use basic marine engines book. I found several and all of them are around $380 used so much for that.

Even though I recommended it I would not pay that much either. I think I paid $17 for mine at Books-A-Million 8 years ago. I really should put it on ebay

[The Hedgehog]

there is no reason not to buy and read the book..

there is actually some very good basic info in there for the novice to digest.. and filter out

however, having said that, don't take everything you read in there as gospel...

:wink:

I thought so.

I agree that it is pretty basic but great info at the time I read the book.

[COOL CROSSBOW]

Got bad news from the machine shop today. The crank is bent .090 in middle.

[BUIZILLA]

The crank is bent .090 in middle. i'm finding that very difficult to believe.......

[zelatore]

i'm finding that very difficult to believe.......

Yes, let's hear more about this....that's an odd one.

[COOL CROSSBOW]

When i took it apart i noticed that the crank had a tight spot when turning it with no rods or main caps on it. I was turning with a 3' bracker bar. So i told the machinist to check it. With a dial indicator on the middle main it moved .090 or you could say -45+45.:frown: