Thinking of getting new intake

[boats&bars]

ok guys help me out here i have a 77 hawaiian daycruiser with a hardin 454 w oval port/ berkley jet AA impeller the motor is stock with a 750 holley I am hoping that you guys have some input on what intake manifold to use, the boat is extremley heavy my top speed might be 40 what do you guys on the boards think i should use??????

[jbone]

On the intake manifold, I am running the Edelbrock RPM Air Gap, and many like this intake in lake boats.
The rpm might be a little low for that one though.
Wouldn't you do better with a smaller impellor? That 4,000 rpm seems a little low.
I have a heavy boat (3500lb+) and I run a A/T "A" impellor.
By the way, I'm no expert!
J

[ghittner]

Unless you have an exposed engine with forced air getting to the intake, like a car gets, or a boat with no hatch cover, l an air gap will not help you with intake charge cooling. A performer RPM is a good choice.

[boats&bars]

On the intake manifold, I am running the Edelbrock RPM Air Gap, and many like this intake in lake boats.
The rpm might be a little low for that one though.
Wouldn't you do better with a smaller impellor? That 4,000 rpm seems a little low.
I have a heavy boat (3500lb+) and I run a A/T "A" impellor.
By the way, I'm no expert!
JI dont think an A impeler will get me out of the hole

[SmokinLowriderSS]

I dont think an A impeler will get me out of the hole
You'd be surprised.
IMO, you are over-impellered.
As a guess, yours is a 330HP 454 (so was my 1978 Indmar), which made about 280+ on a good day (iron dual-plane manifold, very small cam ("GM Hi-Perf Hydraulic", yea, riiiiight), log manifold exhausts.
Hi-tech has dyno'd many a motor like mine (stocker) in years past, and told me they rarely made 290HP in real life.
I built mine on an electronic dyno program after I had it apart and got cam specs, and found MAYBE 290HP right at 4,000RPM, peaking right there.
Spinning a Berk AA in a tight pump 4,000 RPM takes 240HP.
Change the intake and nothing else, you MAY gain 10HP, my dyno program says 3 so you will get nothing if you don't do some other things.
Cut the impeller to an A, gain 250RPM or so, on my dyno program the HP peak is flat enough you don't gain anything there, but you would stand to gain 3 or 4 mph perhaps just from the impeller cut.
Buy the intake for $240, spend $400 or so on a more aggressive cam kit like mine, get 350 real HP from the engine, turn that big AA 4500RPM, and perhaps see the high side of 50MPH.
Expect to spend more fitting the cam tho. I found not only 5/16" pushrods (also the guideplates of course) but short-slot rockers (2 no-no's with my hydraulic setup). I also had to have the guides machined for small seals as my old umbrella seals were a no-go with the 3-piece spring set. That could be avoided tho if you plan to keep the rev's low by leaving the center spring out and stay below 5,000 rpm.
Cut the impeller too, find another 250RPM or so, perhaps see 55mph vicinity.
At this point tho, you may find acceleration cavitation (if you don't have it already) and will be in the market for an inducer to stop that.
It's all money, how fast can you afford to spend? :D
If you are really looking to increase your performance some, the above is what I would do.
I would do it not exactly as I described since I would do a basic rebuild oin it and upgrade some things like the cheezey soft knurled 3/8" rod bolts you will discover if you look. Even GM says "Do not re-use in a rebuild. Replace with new ones".
Also, IMO, the Air Gap should not be as useless in a covered engine as advised for this reason. There is a certain ammount of cooling that will happen to the manifold from the fuel mixture passing down the runners. This can get to be a major effect at higher engine speeds. As long as the direct heat from the valley area oil splash is not heating the bottom of the runners, the mixture should fairly rapidly lower the runner temperature even without the air blowing over it under a car hood.
Also, what air blows over it under a car hood? The 190+ degree air from the fan pulling thru the radiator. It isn't 190* under my boat hood when driving, and not likely when sitting. The hottest my 800-pound heat sink gets idling a long time is about 170*, 140 or below cruising.

[boats&bars]

You'd be surprised.
IMO, you are over-impellered.
As a guess, yours is a 330HP 454 (so was my 1978 Indmar), which made about 280+ on a good day (iron dual-plane manifold, very small cam ("GM Hi-Perf Hydraulic", yea, riiiiight), log manifold exhausts.
Hi-tech has dyno'd many a motor like mine (stocker) in years past, and told me they rarely made 290HP in real life.
I built mine on an electronic dyno program after I had it apart and got cam specs, and found MAYBE 290HP right at 4,000RPM, peaking right there.
Spinning a Berk AA in a tight pump 4,000 RPM takes 240HP.
Change the intake and nothing else, you MAY gain 10HP, my dyno program says 3 so you will get nothing if you don't do some other things.
Cut the impeller to an A, gain 250RPM or so, on my dyno program the HP peak is flat enough you don't gain anything there, but you would stand to gain 3 or 4 mph perhaps just from the impeller cut.
Buy the intake for $240, spend $400 or so on a more aggressive cam kit like mine, get 350 real HP from the engine, turn that big AA 4500RPM, and perhaps see the high side of 50MPH.
Expect to spend more fitting the cam tho. I found not only 5/16" pushrods (also the guideplates of course) but short-slot rockers (2 no-no's with my hydraulic setup). I also had to have the guides machined for small seals as my old umbrella seals were a no-go with the 3-piece spring set. That could be avoided tho if you plan to keep the rev's low by leaving the center spring out and stay below 5,000 rpm.
Cut the impeller too, find another 250RPM or so, perhaps see 55mph vicinity.
At this point tho, you may find acceleration cavitation (if you don't have it already) and will be in the market for an inducer to stop that.
It's all money, how fast can you afford to spend? :D
If you are really looking to increase your performance some, the above is what I would do.
I would do it not exactly as I described since I would do a basic rebuild oin it and upgrade some things like the cheezey soft knurled 3/8" rod bolts you will discover if you look. Even GM says "Do not re-use in a rebuild. Replace with new ones".
Also, IMO, the Air Gap should not be as useless in a covered engine as advised for this reason. There is a certain ammount of cooling that will happen to the manifold from the fuel mixture passing down the runners. This can get to be a major effect at higher engine speeds. As long as the direct heat from the valley area oil splash is not heating the bottom of the runners, the mixture should fairly rapidly lower the runner temperature even without the air blowing over it under a car hood.
Also, what air blows over it under a car hood? The 190+ degree air from the fan pulling thru the radiator. It isn't 190* under my boat hood when driving, and not likely when sitting. The hottest my 800-pound heat sink gets idling a long time is about 170*, 140 or below cruising.
I was going to do the Impeller change and cam last year, I took it to GS marine and told him i wanted a 55 mph boat, he told me that I need 450 to 500 hp to see 50 mph the pump is tight and has a new aa, the previous owner said it took forever to get on plane it will barely pull my fot ass out of the water, I think its just plain heavy, GS suggested lightning headers,intake and Ignition, its just not in my budget, the cam change sounds great but i dont want to pull the heads, I have always upgraded cam and heads all at once, I guess i could do a cam and roller rockers,and intake later .......

[SmokinLowriderSS]

If you can't cam & Intake at once, then the intake is gonna hurt ya. IMO, Cam it and put a 1" or so spacer plate under the carb, fully open spacer, not a 4-hole, to try to help the manifold out, and cut the impeller to an A. You'll actually get more bowl pressure built, with the same flow volume at the higher RPM/HP level in the engine. More pressure = more push on the boat = more acceleration.
The cam on the same intake will help ya more than the intake on your old cam.
Should then be able to get a real 330HP or a bit more from the chevy.
The iron manifold prolly won't hurt ya a bunch till you get arround 5,000 RPM, above 4,500 certainly.
You can cut the impeller later but the recam I think will get you close to 4,500 RPM, and a LOT better acceleration.
My current cam is .565" lift, 280* duration very agressive hydraulic grind custom from Hi-Tech.
My orriginal cam was .461"/.480", 268*/274* duration, chevy "High-Lift Hyd."

[boats&bars]

If you can't cam & Intake at once, then the intake is gonna hurt ya. IMO, Cam it and put a 1" or so spacer plate under the carb, fully open spacer, not a 4-hole, to try to help the manifold out, and cut the impeller to an A. You'll actually get more bowl pressure built, with the same flow volume at the higher RPM/HP level in the engine. More pressure = more push on the boat = more acceleration.
The cam on the same intake will help ya more than the intake on your old cam.
Should then be able to get a real 330HP or a bit more from the chevy.
The iron manifold prolly won't hurt ya a bunch till you get arround 5,000 RPM, above 4,500 certainly.
You can cut the impeller later but the recam I think will get you close to 4,500 RPM, and a LOT better acceleration.
My current cam is .565" lift, 280* duration very agressive hydraulic grind custom from Hi-Tech.
My orriginal cam was .461"/.480", 268*/274* duration, chevy "High-Lift Hyd."
a buddy mentioned the same thing it runs at 5200 wot now but i know that the cam will help.

[jbone]

I will be replacing my RPM air gap for BBC oval heads very soon. Just upgrading from the regular finish to the endurashine. It only has one season on it.
The p/n is 7561
If you are interested, pm me.
J

[SmokinLowriderSS]

a buddy mentioned the same thing it runs at 5200 wot now but i know that the cam will help.
Wait a minuite. WHOSE boat is running 5200RPM, yours or his?
If you are, get a pump rebuild then before you make another move. A Berk "AA" takes 533HP (aprox) to spin 5200 RPM in a well-fed tight-clearanced pump. No stock 330HP 454 from anyone is going to do it.
Internal "slippage" in the pump will give you the fits you are talking about.
Rebuild kit for a DIY'er from Hi-Tech Performance is about $240, plus impeller, Ultimate Wear Ring included. New Tenzaloy (aluminum), about $291, maybe less if bought together.

[cfm]

This is what I have in my notes for most oval port flat tappet cammed 454 330hp motors - your may be different, maybe. I believe typical max recommended rpm for these motors with this cam is 4400-4600rpm.
As you can see, it is very 'gentle' by taking forever to get from seat to at .050" and .200" and using low lift.
Standard Flat Tappet (oval port head BBC's)
GM#3904359
.004” 287*, 302
.006” 278*, 289
.050” 214*, 218*
.200” 111*, 119*
Valve lift with 1.7 .460” , .480”
ICL 110 ATDC
ECL 118 BTDC
114 LSA
================================
An air gap intake does help in covered boat engine compartments. Your fingers will even feel a big difference. Not much difference between non-air gap and air gap on a dyno, but during extended runs it does.
Also, if not using a choke (or if you don't mind disabling the choke) and you are using a flat tappet cam, I'd recommend installing a lifter valley oil splash shield from GM, Milidon, Canton, Moroso, or whomever. GM's is the only one that can be used over roller lifters also.
If you use a non-airgap style intake that has open exhaust crossovers I'd use the Fel-Pro intake gaskets that have steel block-offs that keep exhaust gas from enetering bottom of intake. It's worth the extra 30 seconds or so of warm up time.

[SmokinLowriderSS]

That is the very cam that was in my Indmar 330horser cfm. Due to an old-school loader/grate tho, we were running it 4800+ RPM all the time, 5200+ on 75HP of nitrous.
New Pro-loader went in with the new cam build, so who knows. Then, with 350 REAL HP, I was pulling 4600 RPM for a bit on break-in, 4800 by the end of the year.

[boats&bars]

Wait a minuite. WHOSE boat is running 5200RPM, yours or his?
If you are, get a pump rebuild then before you make another move. A Berk "AA" takes 533HP (aprox) to spin 5200 RPM in a well-fed tight-clearanced pump. No stock 330HP 454 from anyone is going to do it.
Internal "slippage" in the pump will give you the fits you are talking about.
Rebuild kit for a DIY'er from Hi-Tech Performance is about $240, plus impeller, Ultimate Wear Ring included. New Tenzaloy (aluminum), about $291, maybe less if bought together.sorry my buddys boat runs 5200 mine runs 4000 to 4400 I dont want to push it

[boats&bars]

I will be replacing my RPM air gap for BBC oval heads very soon. Just upgrading from the regular finish to the endurashine. It only has one season on it.
The p/n is 7561
If you are interested, pm me.
J
pm'd you

[jbone]

back at ya with a pm.
J

[SmokinLowriderSS]

sorry my buddys boat runs 5200 mine runs 4000 to 4400 I dont want to push it
Ok, got confusing for a moment there. :)