Lol

This is just headed for disaster, budget builds are just that , budget. In the end you`re going to kick your self for not spending a few extra buck and doing it right with the right parts.
If you save a few buck on not having the block checked and tested and it ends up taking a $hit how much have you saved? Nothing, going cheap ends up costing more in the end everytime.

You guys need to really define "right parts". If by saying this you mean he absolutely needs a 4340 crank and the best rods along with 2618 pistons(500hp or below), then again, poor advice. If by saying he needs the right parts, and you are implying he should spend as much as he can on quality valvetrain components that are proven, then yes, this is good advice. Personally I believe in the scorpion marine roller rockers & pushrods(best they have) isky tool room springs, isky locks and retainers, morel lifters, rollermaster billet timing chain. That's my "recipe" for a stout valvetrain.

Why are you using the analogy of not getting the block checked?? That's basic, better do it or else. Maybe over the winter he will be able to fit some of these better valvetrain parts into the budget.

I think his Stock forged reciprocating assemblies(minus the stock pistons) are good for what he's wanting to do with the addition of ARP hardware(ARP 2000) and realistic max RPM. Again the SCAT I beams would be a huge step up, but probably not needed. Guys here have been beating the piss out of wimpy 3/8 330 cast rods with the ARP 8740 bolts for years in big old heavy boats with absolutely spectacular results. His real concern should be Valvetrain durability.

Borgie, you joined here june of this year. I been on here almost 10 years, plus quite a bit of boating before that, and engines before that. I can tell you, that there ARENT many guys beating up 3/8 GM Truck rods in 38 Top guns, 42 Fountains, and 38 Scarabs. Tell me, who's running the 3/8 Truck rods to 5500RPM or better? Any examples?

I personally know 2 local guys that have put GM rods thru the oil pan destroying their block in the process at 6000ish RPM. Busted right at the fastener boss.

The 454 MAG does have a good bottom end. That's why its more desireable than a 330HP 454. Good foundation to build off of. You're absolutely right, in that the stock 7/16 dimple Rods will be plenty for his build. And yes, the I beam scats would be a nice upgrade, and personally I would go that route. To do the rebuild properly, the stock pistons need to be removed from the rod, new bolts installed, rods resized, refinished, etc. I just would spend the few extra bucks and get new rods. Back in the day, a new set of rods was big money, and everyone rebuilt the GM rods. Today, good aftermarket rods can be had for next to nothing. Engine builders like Teague, Ateco, and many others, have a stock pile of GM stock 7/16 rods leftover just for that reason.

Yes, the valvetrain is very important. I run the morel lifters, isky springs, good pushrods, etc. Nobody is suggesting this guy needs a set of carillo rods, and a bryant billet crank.

I guess what I am trying to suggest, to the original poster, is, to be thorough. Everyone pages thru magazines, and everyone wants to assemble their own engines on a budget. Including myself. My recent rebuilds, everything was fine with the engines. I had decent leakdown, good compression, they were good running engines. But they had blowers on them for many years, and felt it was time. There was a lot more to machining than just getting a bore/hone. With new pistons, rings, rods, polishing my crank, boring, honing, line hone, balancing rotating assembly, surfacing the decks, pin fitting pistons, file fitting rings, new timing chains, freeze plugs, cam bearings, magnufluxing , and so on, by the time the shortblock was bagged and on the shelf, I had 3 grand in each one. All work was done on a Rottler CNC . Could I have saved a little money by reusing my 7/16 GM rods with ARP wave loc bolts, maybe. But at the 800HP level, I wasn't gonna chance it.



My point being, is that to do a proper rebuild, machining and tolerances is crucial, and its not cheap. Nobody is telling this guy he needs internals that can support 1000HP. But, I am telling him, if he isn't thorough with the parts he has, or is using, it wont matter if its 300HP or 600HP, it wont live a long life.

You state that you believe in the scorpion rockers, and other parts. Have you used these successfully in your builds? I had a set of crane gold rockers stamped 1985. They just got retired in 2011. In their lifetime they've seen .630 lift and 6000RPM a lot, been in a marine engine their whole life. I went back with another set of them. Because I believed in them from my experience.

If he truly wants to build a 500+HP 460ci engine, why not build a engine that can spin 5500-6000RPM? With his cranks, good set of rods, good machine work, good valvetrain, theres no reason it couldn't do it without breaking a sweat. If he ends up using those Brodix heads and some hyd roller cams, he might be surprised at how much power they make, and how long they can last. Don't forget to upgrade the stock oil coolers and getting rid of the restrictive merc oil lines wouldn't be a bad move.

a person would be wise to listen to the information joe[mild thunder]offers up here on oso,i call him mr research,he has been doing this boat thing for a long time.his little 468s make good power and stay togeather,and beleive me he does not baby them.i know a little about those engines!

Yes, I have not been a member here for long, but I have followed this site and others for quite some time now. This isnt my first rodeo either. When discussing the rod issue, I wasnt insinuating that anyone was spinning them to 5500rpm and such in large old boats. Quite a few here however spin them to 5200(which is a more normal marine engine WOT) without issue. It was used as an analogy if you will. I concur that good quality machining and balancing is essential. I DONT however agree you need to insist on a ROTTLER CNC to have a marine engine that will live. In a higher output engine than the OP's, yes, but where is your data outlining the need for such techniques? Again, ive see many a marine motor last many years in abusive environments with good traditional machining methods used. To me, its more about the talents of the machinist in question, not so much his choice of equipment. Again, any talented machinist knows what works and also has their "preference".

Back in the 60's & 70's my father was a professional unlimited hydroplane driver. He was also one of the only drivers who happened to be a very highly skilled journeyman machinist. We are talking V-12 rolls-Royce/Allison engines that would flatly laugh at this big block crap we are discussing here. The tolerances and setup in a WWII fighter engine like these are much more critical and non forgiving than any BBC. Do you think they had CNC anything in 1968???? uh no, they did not, however with a skilled machinist these engines would swallow large amounts of boost and nitrous in some cases at RPMs they were never intended to see sustained in these 180 MPH boats. My point is, your recommendation that a CNC is required is baseless. You might think or believe it to be, but that does not make it so. Too many variables....

I have used the Scorpion lifters in marine and auto applications with tremendous success. Theres a good reason the newer Mercury Racing motors utilize the Scorpion Marine endurance. They passed a very difficult endurance test designed specifically for marine roller rockers. Again, you have your recipe, and I have mine. Im not an EXPERT, but im also not a green horn.

I'm listening to the guy with a fast blown fountain that holds together if I'm doing a build. I believe in strength for security. Spend a little more now or a lot more later and then you factor in time which is invaluable.

I know of one but not spinning 5,500 and in a 303 Formula.. 465 HP Baker Engineering 454's based on '96 Gen VI 7.4L's. 5 seasons, 200 hours, 5,200 rev limiter. Going strong until late this summer when he reverted water into one coming off plane. Exhaust flapper issue. Boat has participated in multiple Poker Runs.

Didn't know this was a popularity contest. Comparing a 800hp blown fountain build to a 500hp(maybe) N/A build?! Doesn't get more apples & oranges than that. Not everyone here is loaded. And there are quite a few "budget" builds that have shown what's possible. To each their own. I never implied I was an Internet expert. Didn't know hours of research made you an accomplished engine builder. Now I know!

Knot 4 Me

Its good to see some real world evidence. And to hear what led to that mangled rods demise.