i have a stock 454 bbc. I want to give it some more horse power. what is the best way to do this? I have a weiand intake stock heads and cam ad a holley 715 cfm 4 barrel carb.  Iwas thinking about changing the cam but im not sure how much of a difference this will make.  I dont really have the budget to bore it out. I guess my main question is will a cam change make a noticable difference or am i just wasting my money?

ah, you dont want that thing, just give it to me so i can finish my eliminator project, and i will put a video up on youtube so everyone can see it. then you can watch it and show your friends that you donated to a good cause! a broke scjb'r!  haha, what stiff said! good luck!

There is a machine shop down the street that rebuilt my father in laws 454. I will probably hit them up. =They did a good job on his engine.  Thanks for the advice!!!

I say Huff it! 

No, really, Skips got you on the right track. You can literally toss a 20% or better HP increase just by the right cam/lifter/spring package with a good single plane, or really a good dual plane intake. Provided the bottom end is in good shape.

A lot depends on current compression ratio, load, IE, impeller and pump condition, etc.

Anything above a, say "260" cam, is probably going to respond better in a boat with a single plane. Barry, Dave or Paul will correct me here if I'm wrong, but I would be looking at something like a Comp Cams 292 Marine package and a Weiand Stealth or Victor intake. Going to require some work degreeing it in and making sure valve/piston clearances are ok, but a pretty potent package on ANY brand engine and some pretty damn good bang for the buck. But again, the 292 likes compression!  If lower, might want to step back to the smaller cams.

Dunno if this helps or not.

Ray

i tried to post on this topid earlier but i guess my cell phone hate me! anyway if that is a mercruiser block and it is in good shape by all means try to keep it! the marine blocks are a good tool....they are known to have a more nickle/tin content, and work alot better in marine applications!

When we built the motor in our cruiser, back in the mid 90's. We went with the performer RPM intake, performer RPM cam(565 lift), 750 carb, forged flat tops, Crane rockers and old school 97cc closed chambered heads to bump the comp. If it has the peanut port heads, you gotta replace those.

I had a stock 454 when I got the donor hull that i bought. I put some 1.7 ratio roller rockers on it, got some oval port heads, a clay smith cam,  one piece pushrods, an edelbrock victor 454 manifold, 750 4 barrel carb, 10 quart oil pan, high flow oil pump, and a few other goodies and shes happy :-)

http://www.socaljetboats.com/projects/new-to-forum-new-project/

thats my project build thread.

To answer the original question about noticing the difference in a cam change, my answer would be no. There are three basic elements to making horsepower: compression,caming, and runner volume. If you match and balance all three of these things- you will have a noticable increase in power.

I will respectfully disagree...        

Sometimes a cam change will make a world of difference, especially if it is under cammed to start with...Just my personal opinion.

The right camshaft can increase the dynamic compression by leaps and bounds, we found this out running our marathon motor on a dyno with three different setups, the largest carburetor did not necessarily make the most HP, but really effected the max torque and the camshaft change really made things interesting...

What was more interesting to me (didn't really surprise our machinist) was cam timing, 3* was worth 15 HP not to mention about 70 RPM, had I not seen it for myself, I would be a non believer...

Makes sense. But, this guy has or had a bone stock 454. They are typically 8:1 motors. I think it would be silly to throw a new cam in a stock motor to go faster. I think Hallettman is doing the right thing by upgrading the ENTIRE package. It is money well spent. lilrick

I'm with you Glenn on this. He went the right way, and lord knows going to probably more than happy with the results and durability of the thing.

But my thinking is not unlike yours, growing up building hot rods, out of anything from Nova's and Chevelles to even a Ford Granada!(Nowadays they have their own class, "Rat Rods" Little did we know back then we were offending the guys with money!)

But I recall thinking every time, what's an easy, INEXPENSIVE, way to make some good HP? Doesn't have to be easy, necessarily, but cheap, OH YEAH! These are my HS days and still sticks with me, even though, as I grow older, where durability and quality are paramount, I'm still looking for that shortcut. Just inbred in our generation, nothing more, and I look out for that in myself these days. (Miss catching it most of the time).

As machining costs have gone DOWN over the last 30 years, comparatively, taking inflation into account,  for most of us old schoolers, "machine shop" was the LAST thing we wanted to hear. Engine Doctor, Lakesonly and Obnoxious1 can probably concurr, that was BIG BUCKS in those days! We wanted to NOT pull a good running engine, but toss in a hotter cam, intake, carb and ignition and GO. Good 4 Bolt Chebbies, 340 Mopars, 421 and 428 Pontiacs and the good 'ol 390 and 428 Fords (noone had really "discovered" the 429/460 as a hot street engine yet, it was a "smogger" engine to us then) were a dime a dozen back then. Porting and polishing??? Forget it! That was for the mega rich!

Throwing myself back into all this on these boats has made me happier than a fat woman, alone, on Tim McGraw's tour bus. But New School is a LOT different, and better! Found this out on Moo's engine build, big time. But still, trying to adjust dollar value into it, it cost me probably half what it woulda cost me back in my HS days. The current Blower motor, well noone I know of would have even given second thought to it, that was Hot Rod Magazine stuff. Now I've got one (I'm not allowed to put in what it was inended for) and a couple more to build, and they're everywhere.

Just some food for thought. Sorry for the thread jack and rant, but thought it might be relevant. Prolly not, but I certainly feel better!

Ray

origianlly i wanted to gain as much power as possible for the cheapest price.  I figured a cam cahnge would do the trick. after talking to the machinist he said there is no more power to gain from a 8 to 1 comp engine. if you want to increase power you have to raise the compression. the only way to do that is through the heads or pistons and changing pistons is the cheaper way to go.. I didnt want to spend that much but if i have the engine out and apart im going to do it right and not have to worry about it again. He said he is going to bore it out replace and balance pistons, new cam and lifters and rebuild the heads for about $2000. will add about 125 to 150 HP. He also said the water passages in the lower half of my engine were completely blocked with hard sand. he has to clean it out with a coat hanger. He said if i hadnt pulled the motor out to be rebuilt i would have had problems this year with the engine overheating

Hmmmmmm....I think I've heard this somewhere before. I completely agree with your machinest. Sounds like he put you on the right path. Again, not much to gain from the 8:1 motors from just a cam change. What cylinder heads are on the core engine?? Getting back to the basics, Since You are going to bump your compression and are going to purchase a new cam, Now make sure your cylinder heads are worth rebuilding. The optimal cylinder head made by GM for YOUR SPECIFIC applicationwill be the 049 or 781 casting. Throw the big stainless valves in and you will have a very nice engine that will last many years!!!!

these are pretty reasonable

not sure what the casting was on them but i know the machinist said they looked good and should work fine with the engine. He hadnt had a chance to tear then apart yet buy he is planning on rebuilding them.

OK, hold the phone.....

How were pistons ordered if the cylinder head specs aren't known?

The cylinder head to piston relationship is what determines the final compression ratio, nothing else except deck height and gasket thickness can alter this number.

In your original post you stated that you did not have the coin to do a rebuild...Yet here we are.

For the record, if the heads are some 120+cc chambered heads and the engine had flat tops (I'll assume cast) then I would agree on the 8.0-8.3:1 ratio, that being said, if you "bolted on" a set of 90 cc heads with the right gaskets, your looking at a 9.0-9.5:1 deal, throw in the correct bumpstick and a good tune, you're off and running, with an estimated 375 to 400 HP, this all is assuming you had a descent condition bottom end...

I was all excited when I read the opening post that we were talking budget build, most of you had great input, with the exception of TJS Nordic (that guy has issues       )...

I guess my point is, I am glad you have the opportunity to do it from the bottom up, but that was not the original intent from what I gathered and wanted to say that I think it is OK to go half way if that is what you have the means to do.  

If you get the head numbers I would be interested to know, if you feel like it that is....

This is not a blast at anyone, it just seemed that you were being discouraged to build a low compression BBC and I have spent a lot of time and money lowering the compression of the last three BBC's I have (of course one of them was at 13.5:1   ).

FWIW, the 9.5:1 runs the hardest and I run a blend of 50% Rocket 106 and 92 pump gas, the timing likes to be at 37*BTDC, it goes to 5200 RPM and hits a virtual wall.....

From one broke ass boater to another, I hope she exceeds all expectations  

GT