tpabayflyer

I have been a lurker on the board here many years and have a 26 ft cruiser. I just got a Donzi 26ZX with no engine and have a 1995 454 mag carb engine for repowering...........

Engine has no top end but all accessories. 4 bolt block with Forged crank, dimple rods with 7 1/16 bolts and forged pistons as well. All stock and original and the crank looks perfect. Motor has been sitting many years and had a few pistons with light rust around the rings but some PB blaster and light tapping freed them up easily. I am thinking about getting a scat 4.250 crank assembly and the block should easily clean up with a .030 overbore for a 489 stroker. Motor has a real big oil/pwr steering cooler at least a foot long. I am leaning towards getting larger oil lines and nice, high flow connectors as well with a HV oil pump as well.

I would like to see about 550-600HP and over 70MPH.....

I am planning on getting some Aluminum heads around 300/310 Intake port volume and also getting a closed cooling kit as well as there is a ton of room for it. I am on Tampa Bay so this is a salt water deal all the time. Motor is a flat tappet cam so how big can i go without problems with reversion? Thinking about .550 lift range with about 240 duration @ .050 max? Retrofit roller conversion is pricey.... Single or dual plane intake? I am thinking RPM airgap running about 5,200 max? What is a good carb to use? Around 800CFM sound right? Qhick fuel? Holley marine carbs? I do have an LM-1 and will get a jetting kit as well so tuning will be spot on!

I like the EMI exhaust as well to connect to the thru hull pipes...... I am new to performance boating but have many years hotrodding cars .......

I am not going to try and re-invent the wheel here so I want to get info on what are good, proven, and reliable combos for a 600HP carbed 496 stroker..... I want to do this right! Thanks in advance!!!!! TBF

Diego9040

iTrader: (1)

I would love to see what the experts have to say on this thread, I might be in these stage in soon...

wannabe

8-71 blower to get 600 hp out of a 454....

tpabayflyer

Well, maybe 600HP is a little wishful thinking but this will be a 496 motor with good heads that I will probably do a bit of grinding on. With a decent cam and a good exhaust as well should at least be good for 1 HP per cubic inch and then some! It would be great to hear some different combos with single plane vs. dual plane intakes? I have questions about finding an economical or somewhat economical cruising speed where you can cruise on just the primaries only? what RPM and speed? If I could cruise at 50MPH at less than 20GPH that would be awesome.... I want to see if anybody has a closed cooling system as well if i go with aluminum heads I don't want to run sea water through them.....

Diego9040

iTrader: (1)

Laz @ Mesa Balancing offer me to turn my 330's into reliable 496 strokers with reliable solid 600 hp's .
Wishful thinking?

FIXX

iTrader: (2)

Sorry i cant comment on this trend even tho i have built many 496 stroker engines that put out over 600 hp..Some people on here take it as me bashing their trend but realistically its only me making truthful comments..
Good luck on your build..

P.S. all i will say is make sure the coolent passaged in the block are not all coroaded and fust is not flaking off the coolent passages..4.250 crank and rod combo is just a little hard on the cylinder walls and need as much iron as possible..

tpabayflyer

I agree completely! Many 500" big block mopars making 600HP plus easily... takes good heads and good parts combo....... I am sure there are a few guys here that can chime in with their combos..... lets see em!! Anybody have any preference for the eagle over the scat rotating assemblies? I used a set of the scat H-beam rods on my 7.4 build in my wellcraft and they were plenty beefy looking..... How much compression can I use with Aluminum heads and be reliable and detonation free? 10-1 about the max????

tpabayflyer

Thanks... It seems that the slightly longer rod 6.385 tends to reduce the sideloading compared to the standard length 6.135 rod? As far as rust and scaling... yes there is some issues with the block I have. I plan on getting this block sonic tested just to be on the safe side.... My last 7.4 engine I built had the same issues and it checked out good... it is only around 400HP but it is holding up great. These marine 454 blocks are thick!

FIXX

iTrader: (2)

lets say a 315 afr cylinder head and a 10.1 compression,,with the heads being alunimum it like having a 9.0 compression engine..because the alunimum heads disapate the heat so fast you can get away with it at lower coolent temps..

tpabayflyer

Thanks Mr.Fixx... Obviously you have some experience here so please feel free to chime in anytime!!! Do you have good luck with single plane intakes or dual planes? I have no idea what kind of rpm I will end up with and I did not get the prop pitch, but it is a stock 502 bravo 1.... 3 blade.... I am thinking I will not spend a lot of time over 5,000 rpm and the dual plane might be a better choice for me........ C'mon guys.... Let's see those combos.....