Merc 454 330 warm up

[kzcollectr]

This has probably been addressed before but I will ask anyway I want to spice up a completely rebuilt fresh 454 330hp engine I was hoping for some input from those who have sucessfully done this. I dont want to punish this thing but I know there is some power left in it. It has a brand new GIL exhaust with offshore risers. I was thinking cam intake and carb. Heads if necassary.

[DAREDEVIL]

This has probably been addressed before but I will ask anyway I want to spice up a completely rebuilt fresh 454 330hp engine I was hoping for some input from those who have sucessfully done this. I dont want to punish this thing but I know there is some power left in it. It has a brand new GIL exhaust with offshore risers. I was thinking cam intake and carb. Heads if necassary.

First i would make sure u have a 4bolt block !!!!!!

Then i would beef up to 450+ HP ....but if its a 2 bolt , u better of selling it and build from scratch or buy used !!!!!

454/330 + 454 mag, if 4 bolt ,,330 has same then mag.
Then change Heads,cam,carb and u will have 365 HP..also use a crossover,,get rid of the waterpump ...if u now go inside and bore , new pistons and then cam intake heads..u can easy bump it to 450+HP.... !!!!!

[jeffswav]

The 330 has cast pistons, rods and crank, depending on the year it will have peanut port heads or large ovals. This topic has been beat to death and everybody will give you a different opinion. On my engine I pretty much scraped all of the stock parts and rebuilt from scratch. Its a good engine if you leave it alone it will last a long time. Not really made for mods or HP. If you really want to jack with it you could add roller rockers, aluminum intake, and a mild cam. Keep the RPM LOW, others will tell you different.

[YoungPerformance]

Pretty much what Jeffswav said.....it's not a good platform to modify. You could do a few mild things, but you need to keep the rpms low. If you want to add more than 30-40 hp, then it's probably better to start over. You may want to look for a take out 454 or 502 mag or a 500 hp. Those are all good platforms to modify, not to mention they are all quite a bit more hp to start with than your 330 hp. Sorry that this may not be what you want to hear. Good luck.
Eddie

[kzcollectr]

Im not looking for 450hp Im pretty sure the bottom is cast with a 2 bolt block. The 100lb cast intake is going and may go with a mild cam and a new Holley spreadbore It wont be going over 5000 rpm it has aluminum gil exhaust already wanna get as much weight off as possible.

[Ryan8886]

Im not looking for 450hp Im pretty sure the bottom is cast with a 2 bolt block. The 100lb cast intake is going and may go with a mild cam and a new Holley spreadbore It wont be going over 5000 rpm it has aluminum gil exhaust already wanna get as much weight off as possible.

What year is it? Starting around '93 or so, they went to 4 bolt mains in all the Gen V 454's. If that's the case, it will likely have peanut port heads which are for crap. There's a long article published a bunch of years ago...you should be able to dig it up here or on speedwake. There are some changes you can make...cam, intake, heads and carb; but the big question that gets kicked around is the bang for buck factor.

[kzcollectr]

According to mortec block casting #3999289....454.......71-79...2 or 4 bolt main. It has a factory oil cooler. Definately mark IV block. Going to pull a valve cover soon to get a number. I was told the block was studded with a windage tray. It has MSD 6AL Ignition. Its going in a 21 Chris Craft Scorpion so it wont have to work hard to move the boat. A small block pushes the boat 53mph at 4500 rpms with 23p LAZER II

[kzcollectr]

Well I pulled the valve covers and it has the peanut port heads. I have been searching ebay and found a number of the early 390 hp closed chamber large oval port heads at an affordable price. My intake is a flat cast q-jet intake. Im thinking highrise aluminum dual plane and match the cam to this application. I checked the casting date and its a 1973 block.
Im thinkin the closed chamber heads will bump the compression up and the smaller valve/port application will give a nice velocity over a set of open chamber rect ports which are expensive and probably too much.

[ROGUE]

First i would make sure u have a 4bolt block !!!!!!

Then i would beef up to 450+ HP ....but if its a 2 bolt , u better of selling it and build from scratch or buy used !!!!!

454/330 + 454 mag, if 4 bolt ,,330 has same then mag.
Then change Heads,cam,carb and u will have 365 HP..also use a crossover,,get rid of the waterpump ...if u now go inside and bore , new pistons and then cam intake heads..u can easy bump it to 450+HP.... !!!!!

Beg to differ, 2 bolts mains are easily good to 600 hp and reasonable rpm's with the proper fit and ARP studs. Also , leave the water pump alone, its uses little horepower and keeps your temps more stable.

As far a heads go. the best for these things are the large oval ports casting number 049 or 781. They are open chamber. You will not really have enough compression with the stock pistons to do much but if you do change them, dont go much over 9-1 or 9.5-1 if you plan on using pump gas. personally, the edlebrock marine oval ports are not a bad way to go for the money as you will will come close to that money building a bare set of 049's.

Cam, keep the duration reasonable unless you go dry exhaust or you will risk reversion. Ive had best luck with Holly carbs but there are some who have made Quads work.

[ROGUE]

OH, one more thing. Dont scrimp on the valve train, its the weak point in BBC's. Get the best and make sure its done correctly. Broken valve will have you starting over from scratch.

[kzcollectr]

Its going to be a Holley w/ a highrise intake. If you look at the way GM is building the new engines They are using flat tops and reducing chamber size. From what I have read the flame travels across the piston more efficiently than a domed piston. The smaller chamber is supposed to dissapate the heat better. For instance the Fast burn vortec chamber design. Anyone else have any info on this?

[ROGUE]

Granted my knowledge is from rat motor days in the 60's and 70's but the principal was this. Chevy engineers found that they could get reduced emmisions and 30% more air flow (and resulting hp) from the open chamber design when matched to an appropriate cam. And they got it with less compression. Part of the reason was the valves were not shrouded by the wall of the chambers in the head.

I have no info on the fast burn vortecs and how they managed to get the same air in them with the valves shrouded so much. Probably the cam improvements possible with roller cam designs that you just cant do with flat tappets. I assume that modern port design and manufacturing has helped here too.

Make sure you check that the vortec heads will fit on your Mark 4 if you go that route.

There are plenty of us running nearly 500 hp out of what were originally 330's. However, you have to love to work on them and be very very sure they are put together right with the right matching parts or you will have lots of down time. All in all, not even including my time, Im sure it would have been cheaper to sell the stock engines and buy what power I wanted. Youve got to love doing it yourself or leave them alone. There is no such thing as cheap power. The learning curve is expensive and 90% or more of the engine shops will build you grenades. Car knowledge does not work in boats very well.

[kzcollectr]

I hear what your saying and I have built many engines in my day. I come on here and ask questions because building a motor smart will get you the power you need rather than throwing a bunch of parts together and getting poor results. Im not using vortec heads. Im refering to the cylinder head chamber design concept. here is a quote from( Enginelogicsinc.com ) CHAMBER DESIGN :A nice compact chamber is best; that's why the four valve pent roof style chambers are so popular. The flatter the chamber, the smaller the closed volume of the chamber, the less dome you need in the piston. We can get inherently high compression ratios with a flat top piston with a very nice burn pattern right in the combustion chamber, with very short distances, with very good mixture motion - a very efficient chamber. GM has found that the vortec small chamber FAST BURN head burns the fuel so fast the chances of detonation are greatly diminished allowing for higher compression ratios.
They have lots of good info on their site and there are certain laws that pertain to the internal combustion engine regardless of application. Good Reading. Bob Madera has been a wealth of info as well. I will bring him in when it becomes cam time.

[jeff1000man]

Just from experience and what I have read that others have actually done on both this site and OSO.

If you are leaving the bottom of the engine alone and just changing cam and heads. You will like the closed chamber heads better. It is a good way to bump the comp. Invest in a nice cam from Bob madero.

If you are going to take the bottom apart, use a small domed piston and use the 049 style oval head, or buy brand new merlin or edelbrock aluminum ovals with the open chamber and larger valves. Again, invest in a nice cam from bob. It will be a different cam either way.

I have had good luck with these 2 bolt 330 engines. If you stud the block, it will be pretty strong and handle the load. If the crank has not ben turned further than .010, then it can handle the load fine.

The second style is the better equation for the long run. The smaller chmber heads are more of a band aide.

Either way, with this size engine in a marine application, you will be better off using the edelbrock air gap intake with the oval ports. Even with a square port head, you will see better overall performance with the oval intake. If you were turning the engine higher, or putting in a really big cam, then suggest the 454-0 intake. THis is a single plane high rise with oval ports.

Obviously good roller rockers, lifters, pushrods, and 750 cfm 4150 flange carb.

Out of most of the experiments and research that I have seen on both these sites, plus my own personal experiences with some of these build ups, this is the best way and cheapest way to proceed with what you are trying to do.

Keep in mind also, that using the smaller chamber heads to raise the comp ratio is good, but you are working with a cast piston. They will not tolerate the detonation that can come rom a higher compresion. This just happens sometimes with some gas pumps on the waer etc. That is why most of us recomend the larger chamber heads over those pistons, and then raise your comp ratio in the future by upgrading the piston.

Good luck and have fun. That is what is all about anyway/

[kzcollectr]

Getting back to the beginning This is a completely rebuilt dressed engine including bellhousing coupler wiring belts carb etc etc. even has oil and filter with brand new gil aluminum exhaust. So it has new pistons as well I cant see breaking it down to the pistons. This is a plug in engine.

[jeff1000man]

Getting back to the beginning This is a completely rebuilt dressed engine including bellhousing coupler wiring belts carb etc etc. even has oil and filter with brand new gil aluminum exhaust. So it has new pistons as well I cant see breaking it down to the pistons. This is a plug in engine.

Sorry, I just re read this thread from the beginning. If you are going with the cam swap, the majority of guys that have been sucessful with upgrades on this engine, (after a cam swap) have gone with the open chamber oval head. 049 or similar. Use an air gap intake to help in the low to mid range. There are quite a few guys who have posted results after using the head that you described in your first post. Results have varied. With that exhaust, you will be limited by cam selection. With that exhaust, it is best to discuss with either Eddieyoung who posted earlier, or Bob Madero. THey can guide you on the best solution since all you want to do is swap heads and cam.

Bob madero's number is 585-654-8583. It is going to come down to how hard you want to turn that engine.

Good luck.

[kzcollectr]

Bob Madera is doing the cams on my Formula engines. I have been working with him extensively on my small block project. I dont want to hit him with this project till we are done with the vortec small blocks. With his help I should have a very efficent 357 vortecs putting out 370 horse running 5400rpms.

[kzcollectr]

I ran across a set of 049 heads on craigslist for 200.00 price is negociable I may go pick them up today.

[jeff1000man]

I ran across a set of 049 heads on craigslist for 200.00 price is negociable I may go pick them up today.

If they are in good shape and you decide no tot use them, you can probably flip them.

[big97daddy]

BIGDADDY HERE,Just did an engine for son out of 454,has 2 kids and house payment and not an enginer, lawyer,or doctor,just wanted dependable motor to see bikinis while wife was sun tanning her stretch marks,dont guess that makes you all bad,away way.
We started with this mark 4 block which was 2 bolt,had it cleaned and checked for cracks,had it converted to splayed 4 bolt,cam bearings etc. Bought a complete rotating assembly 030 over,steel crank etc,after block was bored block was decked,used large oval port heads,bought new aluniun intake air gap chinese copy I think was 129.00but the important part was the ports were large oval not sguare ones,has a little webber carb and merc ignition with taylor wires,boat also has thru hull exhaust and merc duo prop drive,cam is comp cams marine cam,boat is a maxum 23' cuddy and is probably a little heavy,so is grandma,boat has good powerpulls skiers etc good fuel economy purs like a kitten for about $2700.00 and a bunch of work.
Point is you can build a good little motor that perfofms well and and isgoing to run all day if you take the time and effort to do it.No it dousn't belch fire out the ex and whine like its going to blow up,dont shake and quiver,just purs along,maybe 50 ishon the high side,dont have gps,nobody missed any meals and grandma is still 125 lbs a little heavy