454-330 build up help
 

i know this has been beat to death but there is so much old info on this its almost confusing. I am in the process of rebuilding a friends 1988 454/330. i want to change the cam intake and heads. what would be a good over the counter combo for this motor. of course he is trying to make as much power as he can but this ois going in a chapperal 255sx. not a real performance hull but none the less he is willing to spend the money and make some changes. what would be a good RELIABLE setup for this. I was thinking along the lines of Dart heads torker plus cam and edelbrock air gap intake. what size combustion chambers come with these motors and whats the smallest i can safely drop to on pump gas.

thanx Rob

The smaller, oval-port Merlin heads, an Edelbrock RPM Air-Gap intake and a Torker Plus camshaft would be a great combo to wake up the 330. I think many here will agree. You will get some different camshaft recomendations, but as long as you don`t get too crazy, this combo will work great!
Good Luck!

I am massaging two of these myself over the winter. This board has help in most details of my build. If I had the heads you mentioned I'd be happier. I have edelbrock aluminum rect ports heads I am going to get wedges installed. Going to use the stock dual plane intake. Comp Cams recommended an 11-236-4 cam grind which is 226/236 @.050 and 544/547 lift on a 112 LSA. I believe I am going with the Comp Cam 226/234 @.050 544/564 on a 111 LSA. Going with that cam because I am trying to build cylinder pressure due to flat top pistons. Also, excaleagle on the board uses it and says it works great. It is also cheaper than the marine cam they recommended. Still working on the exhaust system, but may end up with the stock if nothing used turns up. Will use stock tb IV ignition with the quadrajet carbs. My engines started as magnums from 1988. Hoping to eek out 400hp or so.

BT :cool:

I'm interested in this subject also. I've got the same vintage 7.4 / 330 in a 1988 Baja Force 235. I may be rebuilding and am considering the same modifications. I've often heard that if you don't do anything with the exhaust, the intake mods may not do much good.

From what I have read, the real bang for the buck in hp through exhaust kicks in over 500hp. I have the 4" stock system which I don't think will hurt too much with the upgrades I am doing. Would like to have better exhaust, just a little pricey with everything else I am doing (X2). Unless I am willing to redo the rotating assemblies to all forged parts (at least pistons), I think exhaust would be a waste.

My magnums were 365hp with the stock exhaust, so I am sure pumping 30-50hp more through them won't hurt. Just need to be careful with reversion and gasket quality on the risers. That is the approach I am taking until something changes.

BT :cool:

The stock peanut port heads have 119 cc chambers. That amounts to 8-1 compression with the stock flat top pistons. I think the edelbrock oval port heads are 110 cc which will help with compression. I have (still) run that cam in built 454's and am real happy with it (no reversion issues). I personally can get more power out of holleys but I dont know quads well either.

do a search on dyno's 330's on steroids and you will get my combination and results after the mods.....

I recently read 105cc chambers give 8.85:1 with flat tops. Unfortunately, I have 118cc edelbrock heads, so am hoping the lower lsa will tweak my cylinder pressures higher. What do you run for compression Formula? If memory serves, the cam you use has a 114 lsa? Do you know what kind of cranking cylinder presures you have?


BT :cool:

yea, that cam has 114. I wanted that to avoid any reversion with the gil magnum choice setup that put the water in very early. I do run it 4 degrees advanced. Cranking pressures are 125-130 on my gauge which I dont think is calibrated. I am at 8.8-1 compression. I am using trw 2399 pistons that have a slight dome.

Formula, was the purpose of advancing your cam timing 4 degrees to help with cylinder pressures? How does your setup idle.. smooth, rough, high etc?

BT :cool:

The purpose was to get HP peak around 5000 rpm. Idles and starts better than stock or efi, which is no small feat with a holley carb. I looked at a lot of cam timing on a lot of engines (older merc hp) (#1 intake cl around 106 if I remember right, Ill check) and read a lot of books and tried all three (+4, 0,-4). Adding 4 brings gets the intake valve pretty close to the piston (.080) but that value is livable as long as you dont spin it too high. I dont pretend to understand exactly what is going on in there and why the +4 works better but it seems give me more power at 5000 rpm. In theory, advancing the cam brings the hp peak in at lower rpm and visa versa. I did this playing with a single engine boat and adjusting the cam timing with a cloyes hex adjust and a timing cover with an access plate. Im convinced but it may depend alot on all the other engine parts and how many rpms you want to spin it. It would be interesting to see if Dennis Moore chims in and what his opinion is. I got some of this information from Alex Walordy, another HP guy and other old time engine builders from the early Hydroplane days.

Also Bill Fisher and Bob Waar.

Formula.. isn't warlordy the author of the bbc performance marine book you said was good? Where can I find that?

BT :cool:

Not marine though, just old chevy hi performance ideas. I think Summit may have them. "Chevy High Performance Engine Assembly Guide" Alex Walordy. and a better one is "How to Hotrod Big-Block Chevys" by Bill Fisher and Bob Waar. keep in mind this is old tech and has to be tempered for marine use but there is some good info there. Dennis Moores book is better because it is based on marine use.

You can mill the block and the heads to get just a little more compression too. Not too much or you will throw off the intake alignment.

I also have done some things to my 330. It's .060" over stock, has slightly domed hypereutectic pistons...Merc. magnum dual plane intake.....cam, some mild head work to the Merc. magnum rect. port heads.....and EMI exhaust. From one summer to the next, I gained nearly 6 mph in my 1987 Baja 240 Sport. Not an easy feat by any means. Heavy boat.

dyno and I have similar motors, he has a slightly hotter cam than I do and better heads.....but both motors run really well. You can email Crazyhorse for part numbers if you want. He was a big help to both of us (and several others here on OSO).

Mike

my .02
I run twin 454 330's and have Edelbrock 750 cfm marine carbs, RPM performer airgap manifolds with IMCO thumper exhaust.
I run 48-4900 RPM with air temps of 50 f or 100 f. It makes no difference thats all the RPM I can pull. Our thinking was that the oval "peanut" heads will only flow so much air and that is my weakest link in my system, for now.
I was told to get anymore RPM's from a stock setup and not changing cams, I will have to go to rect. port heads.
To port and polish a set of ovals isn't worth it. The rect. will flow more. The cost to "flow" a set of ovals, you could buy a set of CNC rect. port heads and not have to upgrade again.
Also this is on a Formula 272SR-1 so it's heavy

One of the first things I would do is lose the flat tappets and go with a hydraulic roller. 30+ hp by that alone. The larger ovals will run just fine up to high 5000s. You might try fooling around with desktop dyno a little and see the difference in the torque curves of single plane vs dual on these combos. Good for ~40-50hp on top with not much diff in between. I've ran a crane 226/236-587/610-112 in that motor with Edel oval heads and a dual plane with great success. Would go with a Single plane and a Holly or Demon if do over..

Yea, there is a huge difference between the peanut port oval heads and the old large port oval heads that are arguably better than the rectangular ports for most marine engines.

'Bago Baja,

What kind of speeds are you getting with your 7.4 in your Force? I have basically the same boat - 88 Force 235, but mine started out with a 350 mag/Alpha. With that combination it would run 48 - 52, depending on conditions and how loaded down it is. Since that time I have swapped in a warmed over 454/Bravo. I now run around 60, but I expected more. Mods to the engine include large oval heads with 2.19 intake valves, Comp Cams Xtreme Marine XM270H (226/236 @ .050, .544/.547, 122 LSA), TRW forged pistons with a small dome, edelbrock Performer RPM, full roller rockers, etc. Heads had some minor valve pocket work done on them. I'm running the stock Q-jet with larger primary and secondary jets & rods. Stock Merc Silent Choice exhaust. Pretty similar to what has been mentioned here. I think the Q-jet might be holding me back some - would like to try a Holley this year. I honestly expectted about 5 more MPH out of this combo, as my friend's 89 Force 235 used to run 58-59 with a well worn 7.4. I'm also suspicious that the 1.36 gears in my Bravo might be holding me back - if you search through the threads you will see some discussions of the 1.5 vs. 1.36 ratio in the Bravos.

Interested to hear about your combo and what you end up with.

Budman.. that is the same cam I am considering seriously. Do you like it? How does it idle. How does it sound? Would you use it again?

BT :cool:

BT,

For the most part, I like the cam. It seems to have real good midrange power, and it has a nice aggressive sounding idle, yet I can still idle at 600 - 800 RPM with no problem. I'm running it with Merc Silent Choice, which I use often, and so far no sign of reversion. However, as I mentioned, I really expected to see more speed out of this setup. Not necessarily the cams fault - could be a bottleneck elsewhere - perhaps the Q-jet & the stock exhaust are holding me back. Might try a Holley 750 this summer just to see if it makes a difference. Judging by the amount of midrange power that I am making, I think I might do well to try to move the power band upward in the RPM range - maybe with an open spacer under the carb, or even a single plane manifold. Also, I think I might be jetted a little on the rich side, but I would rather run rich than lean - less chance of torching something.

If I had it to do over, I might consider a cam with similar duration and overlap, but with more lift - maybe something in a hyd. roller. If you are running a performance exhaust, you can probably be a bit more aggressive on the duration and overlap and make a little more power.

Budman,
I'm running the stock 1988 7.4 / 330 merc, Bravo 1, 1.5 ratio, 23P Mirage @ ~4200 rpm's. Gives me ~ 57 on the speedo with two people and 1/2 tank of gas. I've talked to two others with this boat / engine combo who say they get 57 mph out of the stock setup. I'm trading my prop in on a labbed 21P with additional cup (Houston Propeller) as a first step with 4600 rpm as the goal. Hope to pick up a couple mph. I'm considering the same basic mods that you have done (except pistons, I'll probably stay with the flat tops) and would surely expect better than you have seen. I'm reading Dennis Moore's book right now. He agrees that large oval heads with oversized valves are the way to go along with a moderate cam and performance manifold. Dennis swears by the QJ and says it's good for 475HP on the BBC. I doubt your approaching that point yet. Dennis also stresses the importance of advancing ignition timing with performance mods if rpm's are increased over stock. Requires a new module on the Tb IV ignition system. He gives a procedure in his book for finding the right amount of advance at idle and WOT. blue thunder says the stock exhaust should be good to 500HP. Dennis Moore says "The biggest roadblock to improving performance with a marine engine is the exhaust." I don't know what to think. Just passing along what I've heard / read. What rpm's and prop are you running?

Budman... my other choice is a comp cam 226/234 @.050, 544/564 lift with a 111 LSA. Kinda like the tighter lsa and it has a slightly higher lift. Any opinions on that? I too am going to run the q jets and tune as Dennis Moore recommends. Hoping they will work out ok. Bago Baja... I think the stock exhaust will continue to work ok through the 400 - 500hp range, but certainly becomes a limiter at some point. Probably any hp engine would run better with performance manifolds where the exhaust pulses are seperated. It is all kind of debatable... make your best guess.

BT :cool:

Budman, I have a high rise single plane intake if you want to try one. I could send it to you, you can give it a run, and if you don't like it, send it back. If you do, we can talk price at that time. It's a Holley Stip Dominator for oval ports.

Mike

Well, 12 years or so ago I also cringed at the cost of performance manifolds and then it was pretty much CMI or Gil. I went ahead and did all the engine stuff and ws disappointed. I finally got a set of Gils through CPperformance for $1400 and picked up 400 rpm. After that I was convinced. I think if you are gonna blow the motor with a procharger or a roots blower, the stock exhaust is fine to a point, but for NA with a performance cam, it really needs the reduction in exhaust backpressure and the seperated runners. Over 500hp NA, full seperate primarys are needed.

I have heard plenty of people with injected engines that put on aftermarket exhaust and did not see much improvement. I cant answer that one, but I know what it did on my carb motors.

BT, I cant wait to see how that cam works, I looked at that one too but was scared of reversion.

Formula... so you think I should try excaleagles 544/564 cam? I think I am there. What do you think of the imco SS risers with the stock manifolds? Worth anything?

BT :cool:

Wow, I dont want to tell you what to do for a cam. I stayed on the conservative side. The one you listed may be fine, Id keep the idle up a little though. Inconel exhaust valves too.

No, the problem really is the small hole at the top of the manifold and the open chamber that causes all kinds of cross pulse issues with a bigger cam.

HEY GUYS I'VE DONE ALOT OF THIS AND THE CAM ABOVE IS A KILLER ONE ASK THEM TO GRIND IT ON A 110LC AND 4 DEGREES ADVANCED YHEN INSTALL STRAIGHT UP BE SURE TO HAVE 8.75 TO 9.0 TO 1 ,,IT IS NOT BIG ENOUGH TO HAVE REVERSION ,AND FOR EXHAUST A CHEAP WAY OUT IS CHANGE TOPS AND CUT THE WATER WAY DOWN GOING OUT I WELD UP THE WATER HOLES IN THE STAINLESS TOPS AND DRILL 2 1/4 INCH HOLES THEN SEND THE REST DOWN THE Y-PIPE OR ON THE DRIVE WITH A DUMP ,,,,REMBER YOU CAN'T COMPRESS WATER SO IN EXHAUST ITS BAD

ALSO THE QJET IS OK WITH WORK AND A DUAL PLANE INTAKE

HOPE THIS HELPS BOBBY

Thanks Bobby... great input. I only have somewhere between 8:1 and 8.2:1 compression at the moment. What affect would this have?

I have thru hull exhaust and am shopping for used imco risers to mix water further away, but may still use stock 4" risers if nothing is found.

Thanks for the help,

BT :cool:

bobby,
Please explain this cheap way out for exhaust. What are the tops? What do you weld up and where are the holes drilled? Is this a modification to the stock exhaust?
Thanks,
Tom

I just built mine up and am 150% disappointed with my results
I did 9.5:1 hypereutectic pistons
Swapped peanut heads with large ovals
installed edelbrock performer intake
Comp xe-268H12 11-242-3 224/230 515/521 110 LSA
With rochester I produced 331 HP
With 750 carter I produced 365
With 850 Holley I produced 387 HP all in and around 4500-4600 RPM's
This was tested with Gil Merc HP 500 exhaust
She fell flat on her face
with the up in compression from 8 to 1 to 9.5 to 1 I thought I was in and around the mid to upper 400's in HP
WRONG
this was a real POOR choice of cams, I do NOT recommend it what so ever.
peaks at 4400 which is fine, but choose a cam that is more going to peak towards the 5000 mark and just have enough carb to spin it that high.
more than 5000 r's on a cast crank is okay, should be fine, but for reliability purposes, I would not push it or your going to have issues at some point.
the large oval heads stock, not worth spit, either get rectangle heads or dont get heads at all
these large ovals are basically worthless over the stock peanut heads and arent worth a crap unless you can sit there and port the hell out of them and like someone else said, you might as well just buy the rectangle heads cause your going to go broke opening these up more.
I got this cam out of the list of Dennis Moores book and it says okay results on a stock 330 but on the dyno, more or less sucks monkey balls.
if you want to produce a major increase in power on a 330 you have to get aggressive with the parts.
dont buy intermediate stuff, go for the big stuff
you can always keep it for other boats and keep stock stuff to put back on to sell it.
Good luck
Jason

I USE C.P.OR SOMEOTHER STAILESS RISER AND WELD UP THE WATER HOLES AROUND THE EXHAUST THE REDRILL 2 ,,1/4 INCH HOLES AND ADD A DUMP TO THE SILENT CHOICE Y PIPE OR TO MAKE A SHOWER TO THE DRIVE TOP,,
TO KEEP AIR LOCKS OUT AND THIS REALLY WAKES THE BOAT UP
TO GET THE WATER OUT AND THE NEW ANGLE RISER
PM ME WITH YOUR NUMBER AND I'LL GO INTO MORE DETAIL IF NEEDED I CAN'T TYPE WORTH A ^^%^^$^
BOBBY

TRY TO GO 8.75 ITS WORTH A GOOD BIT OF TORQUE ,YOU NEED TO GET WATER OUT ,OUT OF THE EXHAUST FUTHER AWAY WILL NOT HELP I CAN HELP WITH SOME RISER IF NEEDED PM ME WITH NUMBER I'LL GIVE YOU MORE INFO

ANGLE CUT HEADS ,I DO IT SO THE STOCK UNCUT INTAKE WILL FIT 40.00 /ITS EASY
LATER BOBBY

Waterfoul!!
 

'Foul,

Thanks for the offer. You've got mail!