Building a reliable 454 - Team Camaro Tech
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post #1 of 14 (permalink) Old Sep 16th, 12, 03:08 PM Thread Starter
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Tom
 
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Building a reliable 454

I know this site is for Camaro’s and not a boat but my question is geared toward the 454 BBC. Thx
I have a 88 Correct Craft Barefoot Nautique with a factory PCM 330 HP 454. Doing a restoration this winter and want to freshen up the motor. This motor is a stock hyd cam 8:1 compression peanut oval heads and a 650 Holley with marine points dist. It turns ~ 4200 RPM.
My Goal is to keep fuel consumption at a minimum while making a little more HP and a mild increase in performance on a minimum budget.
My initial plans were to just do a lower end fresh up with gaskets, bearings and new hone job w/rings while not replacing the cam or Holley Carb.
I am considering are add a set of 336781 with stock valves, add Edelbrok EDL-2161 and Pentronix electronis ignition module.
Thx.....Tom

Last edited by copol78; Sep 16th, 12 at 03:17 PM. Reason: updates
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post #2 of 14 (permalink) Old Sep 16th, 12, 08:05 PM
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Re: Building a reliable 454

the peanut ovals are closed chamber -the 781s are open chamber-if you got 8to1 now -you wont have any with 781s which means changing pistons and would change the cam also
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post #3 of 14 (permalink) Old Sep 16th, 12, 08:40 PM
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Re: Building a reliable 454

Tom, what is the casting number of the heads you have? I believe the peanut port heads typically have combustion chambers somewhere around 118 to 120 cc - but they vary.

Here is an interesting article about modifying the GM 236 Iron Peanut Oval Port heads.
2.06/1.72-inch valves
120cc chamber
Intake-port volume: 208 cc
http://www.carcraft.com/techarticles...s/viewall.html

You will have to scroll down in the article. The peanut port heads would not be bad for a marine engine and the lower rpms you would typically run. Just need some porting and maybe larger valves.

One other option would be some mid to late 1960s closed chamber large oval port heads. Casting numbers ending in 702, 390, 802, 215, 063, etc. have combustion chambers around 100 cc. They would increase the compression and probably flow well with some port work and larger valves. I think those would work with your block.

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Last edited by bcm66; Sep 16th, 12 at 09:17 PM.
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post #4 of 14 (permalink) Old Sep 16th, 12, 09:36 PM
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Re: Building a reliable 454

Beware that it gets tricky if you actually decide to change the cam. Jet and prop drives are essentially behave like a water dynomometer in the sense that they are designed to absorb a certain level of horsepower at a given rpm. The reason I'm bringing this up is that if you change to a hotter cam later, you need to be careful that you don't push the power band to higher RPMs and not have enough midrange to pull the pump/prop up to the motor's power range. If that happens, your boat will actually go slower. Slightly more compression, better head flow, better exhaust are all safe mods, but cam choice must be carefully matched to your jet pump or prop pitch. Kind of like putting a big cam in a car with 2.73 gears, it will run but it will be a dog until you drop the gearing . Good Luck!

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post #5 of 14 (permalink) Old Sep 16th, 12, 09:53 PM
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Re: Building a reliable 454

Good points DAN
PP heads are OPEN CHAMBER as are 781s
PP heads make more low end grunt and in the range of the boat, certainly adequate/probably the better head
CAUTION about raising CR too much, heavy loads over the long haul vs occasional peak runs...whole different game.

I am not a boat guy but I did sell a boat guy my Super Budget 454 from my El Camino. I removed my closed chamber ovals and installed some PP heads with good valve springs. CR 8:1 with the flattops. Cam was the Crane 226*/.533"/108LSA. A week later I spoke to Boat guy... he was AMAZED by the engine, said night and day difference.

I believe the Marine Cam is 228/238 .540/.540" 114LSA

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post #6 of 14 (permalink) Old Sep 16th, 12, 10:27 PM
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Re: Building a reliable 454

Quote:
Originally Posted by copol78 View Post
I know this site is for Camaroís and not a boat but my question is geared toward the 454 BBC. Thx
I have a 88 Correct Craft Barefoot Nautique with a factory PCM 330 HP 454. Doing a restoration this winter and want to freshen up the motor. This motor is a stock hyd cam 8:1 compression peanut oval heads and a 650 Holley with marine points dist. It turns ~ 4200 RPM.
My Goal is to keep fuel consumption at a minimum while making a little more HP and a mild increase in performance on a minimum budget.
My initial plans were to just do a lower end fresh up with gaskets, bearings and new hone job w/rings while not replacing the cam or Holley Carb.
I am considering are add a set of 336781 with stock valves, add Edelbrok EDL-2161 and Pentronix electronis ignition module.
Thx.....Tom
To change cams to get the best performance in the 4000-4500 rpm range talk to a cam mfg. Crane is very helpful. They may have prop suggestions to move more water at the same rpm because it makes more power. Oval ports are a good choice. Most any automotive BBC head before 1970 should be oval port and closed chambers. Adding 2.19 / 1.88 valves vs the stock 2.06/1.72 valves adds a few extra HP and mid-range torque.

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post #7 of 14 (permalink) Old Sep 16th, 12, 10:48 PM
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Re: Building a reliable 454

Also camming it to move the torque band up to where your operating range is will save some fuel at cruise. Typically you get your best brake specific fuel consumption numbers around the torque peak, although moving torque up means hp is going to go up at a given RPM. A 330hp 454 sounds like a tiny cam to give it pretty low torque peak RPM. BSFC is like an upside down bell curve...low at the torque peak and high on either side.

Let's say you make 450 lb ft peak but only 375 ft lb at 4200 now and just guess that given the 330hp rating on the engine that it's an the downward slope of the torque curve at that RPM so BSFC might be 0.55 or so. That'll give about 300 hp at 4200 and fuel consumption of about 165 lbs of fuel per hour.

Now let's say you move the torque curve up to 4200 so you get the full 450 ft lb at 4200 RPM and that your BSFC drops to 0.45 because of this. Even though you now make about 360hp at 4200, your fuel consumption drops down to about 162 lb per hour.

All of that is just academic though.

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post #8 of 14 (permalink) Old Sep 18th, 12, 09:07 PM
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Re: Building a reliable 454

Tom, are you out there?

68 Camaro SS 396 - 468 BBC now, M21, 12 bolt 3.73 coded housing but w/ 3.31 gears.
Looking for 68 Camaro with body number NOR 181016
CRG -
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post #9 of 14 (permalink) Old Sep 19th, 12, 07:03 AM
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Re: Building a reliable 454

I would start with some cheap and easy stuff first....like a K&N filter, perhaps some exhaust mods, and roller rockers.....synthetic oil too.

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post #10 of 14 (permalink) Old Sep 19th, 12, 10:05 AM Thread Starter
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Re: Building a reliable 454

Thanks guys...SOrry I have been in overload with work and other issues. The 454 pulls skiers pretty well as a stock PCM 330 HP motor. I can change the prop to a more tech advanced and have more torque (hole shot) and increase RPM to 5000. All I was trying to do was change heads/intake/distributor to allow better breathing and some increase in performance. (Low budget)
This is a Left Hand rotation motor and cams are a special grind (I have been told and they are priced arounf $450.00) DO not need to go there.
So my improvements are focused on heads intake and a electronic ignition. For heads mabey bigger valves and some porting to match the intake. (I can do that myself in the garage) Any thoughts. I will get the head part numbers this weekend. Thanks to everyone for input.....
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post #11 of 14 (permalink) Old Sep 19th, 12, 10:53 AM
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1st off - is this a typical Reverse Rotation Correct Craft - 'nevermind' ...
(You updated this in while I was typing reply ...)

Will need to know more about what you want - besides 'more performance without effecting the fuel consumption' ...

I build lots of marine application engines, and they are usually easy to spec. if the customer has a clear vision of need(s).
That said, I've found most have responded very well to a swap from Carb to EFI - as this gets you some increased performance (along with supporting mods) and the best fuel consumption rate you can get with most combinations in the widest operational range.
There are numerous aftermarket suppliers that can furnish 'turn-key' stuff or you can piece the system together with readily available parts from auction sites and other sources, depending on you needs/talents.

The 781 heads are a good upgrade, but will need other intake system mods to shine.
The 96 and later Vortecs can also be a good mild marine performance upgrade head. Their smaller 105cc will raise CR vs. the standard 'Open' marine heads.
But to increase the cam spec.s for either (or just about any) head choice means you're into valve spring changes.

Is your cam stock?
And what is the Firing Order of the engine?


Looking forward to feedback and further discussion

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post #12 of 14 (permalink) Old Sep 19th, 12, 08:33 PM
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Re: Building a reliable 454

Ah, the old barefoot nautiq. Are you pulling slalom skiers or footers? I had a mastercraft and a Malibu, the rpm is 3400 for slalom to wot for footin. An Alluminum set of heads will save you 70 pounds, and that alone will make a difference, it may be cost effective to look into a set.

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post #13 of 14 (permalink) Old Sep 20th, 12, 03:12 PM Thread Starter
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Re: Building a reliable 454

Strictly Barefoot watersking.....Our speeds range from 25mph (shoe ski practice) to wide open at 44 mph. The motor runs fine and never misses a beat, but I have a oil leak and plan on pulling it out of the boat this winter to clean it up and detail the engine bay, motor and trans. So I thought while I have it out I would do a freshen up with a hone, rings, bearings and gaskets. Secondly I though I would do some low budget improvements. Mabey a edlebrock performer rpm intake ($225.00) and 336781 heads (approx $500.00 core + rebuild). Guess where I am going will those changes buy me anything as far as performance improvements or is that money thrown away. If so is there a better set of heads/intake for a little more torque and top end? Thanks....Tom
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post #14 of 14 (permalink) Old Sep 20th, 12, 03:31 PM
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Wink Re: Building a reliable 454

And a Cam
Don't forget what a lame stick GM stuck in those truck engines
Call Lunati/HD Harold and talk to them about a mild (not hard from where you are now) upgrade to improve upper throttle breathing via a little more lift.
It can still idle great and the mid range acceleration will be improved with the right profiles.
Lunati still had some RR blanks last time I spoke to them

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