Intake off Gen IV 454 420hp
 

Will my intake off my Gen IV 454 420hp mount onto a Gen IV 454 330hp engine? Or are the intake ports different? I'm assuming the heads on the 420 are stock.

people do it but don't, the 330 is oval port, the 420 is rect port..Rob

Whats a good intake for that motor then? Have a Holley carb.

Here ya go!http://www.cpperformance.com/SearchR...D=157&Vendor=2
We carry Hardin, edelbrock, wieand, dart, merlin. We also can hard annodize for salt water applications. Let me know if I can help you more. Thanks!
Brian:drink:

edelbrock performer rpm air gap would be a great choice for a 330, run a 750 and you should be good to go..Rob

Couldn't agree more,
RPM Air Gap has apparently been rated the best performing inlet manifold under 5000 rpm by Car Craft Magazine! (even against Dart, Merlin and other Single Planes!)

I had an oval port Air gap, ordered the WRONG ones, just sent it back a few weeks ago IIRC Summit has the best price ($245.00)

Nice pieces.

Intake
 

Whats the consenses on the intake used on a 496 (stroked 454) and a demon 750 with dart alm 310 cc alm. heads? Mine seems to stop at 4900 was wondering why ? running a crane hyd. roller specs say 5600 only running 23 mirages. Am I running out of air ? Some say 850s at least?Or is it the intake?

when you say cam specs say 5600, but for what cubic inch engine, that cam may do well to 5600 in a std 454, but with your stroker may only work to 5000. what intake are running ? the 750 seems small to me, altough I'm running a 750 on my 509, next season I'm going to swap a 850 and see on gps what its worth...but thats months away...Rob....

intakes
 

the 330 motors came w/round port heads,not oval.i have been told that this is the same head used on big trucks.i had a 330 motor in a 22pachanga w/a q-jet carb on top.best i could run was 58mph on gps,22rh cleaver.i changed the intake to a eldelbrock performer w/q-jet flange.it took the speed to 60mph.i then removed the q-jet and put a holly 800 double pump.speed went to 64.4mph.the holly uses more gas,but better speed.i think the round port heads stop flowing good around 4500-4800 rpm.hope this helps.

I got the same problem, 4 different carbs and 4 different props and it still only turns 4900... 454-425 crate motor

Just because 5600rpms is what the cam is designed to run at for max rpm, doesn't mean it will in your boat. Your heavy boat needs torque and your engines are probably starting to fall off in torque too much at about 4900rpms. Go down 2" in pitch on your props.

I agree, a 750cfm is on the small side for 496ci.

rpm air gap
 

496 ci, rpm air gap intake Motors pull way to good from 3800 4900 if it was props it would take waaaay longer to get there.iIt will accelerate from say 40mph about 3800k to 60mph 5k inabout 3or 4 sec. This boat with stock 330s and 21 pitch would run 5300 5400 and around 52 55 . Ive dynoed the motors and there double the trq. almost double hp.

I dynoed them and yes trq. is starting to fall but its still over 500 ft pnds peek is around 4k at 610 way more than a stock 330 merc. If I go down in pitch I wont be as fast as stock 330 if Im thinkin right

What props are you running now????

23 mirages

My mechanic and also the company that sold me the motor said that I would be able to put my intake off the 420hp on the 330hp. Just wandering what kind of results I'm gonna see. I could get 60-62 in a 88 240 sport with the 420, but its really tired ( mechanic said probably only puttin out 325hp). I'm hopin to see the same if I take my setup off the 420 and put it on the 330, with a few adjustments. Anybody do anything similar to this and what were the results.

Looking back at another thread

You need some aftermarket exhaust!!!!!!!!! The engine can't breath.

Your rpms and prop change indicate that you are making same power at 4900rpms now that you were before teh engine mods.

yes you can put a rect port intake on a (I still call them oval) heads, but the port mismatch is going to cost you !

What do you mean its gonna cost me? Do you mean the engine itself is not going to run as well as it would with matched ports? And if I'm correct the ports on the 330 are considered oval, they are just the small oval and there is also large oval ports (maybe this is wrong, I'm still learnin. Thats why I'm posting).

I've run large oval (intake) with a stock 330 head. I'm sure it's not the BEST combo, but it does work.

ptlmveng-

The 420hp intake will work on the 330/454- won't be the most efficient intake but it will work. Depending on what is wrong with your 420/454 you might be much better off freshening that engine. The 330/454 with an intake change is not going to run anywhere as near as strong as the 420 motor.The 420hp/454's have a lot of good parts inside of them.... just my two cents.

Rick

the 420 block was cracked and had been repaired. As well as one of the heads developed a crack this summer. don't know the extent of the crack or anything. Got water into one of the heads that messed up a few valves. Not sure if that was the block, head, or riser gasket that failed. wasn't worth taking the time to find out it wasn't worth rebuilding. Didn't want to spend alot for a motor so i just went with the 330hp. Just hoping that the old 420 with over 700 hrs and other problems that it was only puttin out somewheres in the 330hp range. this way I'll be in the same boat as I have been (no pun intended). Everybody, including myself, wants to go faster. But somewheres around 60mph and the great sound of thru hull exhaust, I'm completely satisfied. I think the 330hp is a pretty reliable motor that will give alot of trouble free boating.

The 330hp is a great motor- low maintenance and very reliable. Who knows with a cam and head change it might run even better...
Good luck with it :)

it just so happens I'm rebuilding two 330hp mark IV's. for cash sake I will use existing heads (replacing 1 with a crack) I have some 496 take off exhaust and will be replacing the tips with 4". I'm looking for advice on what cams to get, I believe I will be going with the eldelbrock performer RPM Air Gap intakes. (had them in mind but made the decision after reading the first posts of this thread) the question... what cams, I want from the hole to 5000RPM. there seems to be a wealth of knowlege here so I will shut up and learn!!:ernaehrung004:
happy new year all
Bobbo

just buy a decent oval port intake...the mismatch ports interup the flow and kill power...just like trying to put the square peg in the round hole.....now that should make it understandable....and yes they have small(some call peanut) oval ports and large(which work very well on boats...Rob

on the other question, you are right on wityh the intake, I would contact comp, crane, or rmbuilder on here, understand he is the cam guy here...Rob

I can't find a decent intake except for stock cast that has small oval ports. Only thing i can find is large oval ports on intake. Isn't that essentially going to be a mismatch also causing the same flow issue?

not nearly as bad as the rect will be....

Guess I'll have to see how it works out. I'll probably try it and see if I have any problems. What intake is everyone runnin on this motor thats not the stock intake? Edelbrock with large oval ports?

RMBuilder/Bob Madara (Marine Kinetics in N.Y. 585-654-8583)is the man with the cam! Bob will give you the BEST cam advice you will ever get. He has helped many guys on here with a cam selection for offshore hi-perf marine use including me. He's very professional and a pleasure to work with.