Finally got a bigblock need advice..

[jason7698]

So I decided not to go with the 496 but instead I got a great deal on a 454 bored .30 over and need to know what carb and intake to get she's going in a 1971 c10 weekend cruiser it will be bolted to a built th350..Here's what I know about the engine...

1981 454 bored .30 over
hypereutectic flat-top pistons w/ stock rods
stock bottom end
stock oval port heads
Lunati 543 lift 290 duration hyd. flat tappet cam

Engine is freshly machined with new cam bearings and heads gone through need carb and intake suggestions/advice...Thanks
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[CC69Rat]

I'm thinking an Edelbrock RPM, or RPM Air Gap

Holley 3310 (750cfm) 72 jets in the primaries, 76 or so in the secondaries.

Oh, HEI distributor

[1quik70]

I'd go with exactly what is stated above! If you can afford MSd ignition, it's nice not to have to worry about it, but totally optional.
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[jason7698]

I think I want an electric choke what do you guys think?

[CC69Rat]

Summit sells what they call a Street Fire Distributor. HEI, made by MSD. In fact it even says MSD on the base. IF you don't want to drop the $ on the pro billet, I'd recommend this dizzy. That's what's in my BB.

Electric Choke is worth it IMO. ..

[1quik70]

I'd say the elec. choke would be a worth while investment. Maybe you have thought about it, but you coolin system will probably need some attention as well, those BBC's tend to run a little warm. Cheapest route is a Professional Products 31x19 Aluminum radiator and a stand alone trans cooler. I think I did the whole setup in the Nova for under $300!
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[FrankieD]

Found this:

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I have often seen many people over carb their vehicles because the size of the carb sounds good when bench racing. However, in the real world, the carb needs to be sized according to the use of the engine. Here's some formulas to help you decide what carb you really need, and what is really too much to be a benefit to your ride.

CFM = Displacement * RPM / 3464
This assumes a Volumetric Efficiency of 100%. If yours is known to be less then use the formula below: CID * RPM * VE / 3464

Say I have a 350 small block that is rated for 6000 rpms max
350x6000= 2100000
2100000/ 3464= 606.236
so roughly a 600 cfm carb would work fine up to 6000 rpms.

It can be reversed
If you have a 750 Holley and want to know if its too big for your engine try this
cfm (750) x 3464=2598000
259800/ max rpm (6000 in this case)=433
so unless you are turning your engine more than 6000 rpms( around 7500 rpms to be exact) or have 433 cubic inches or more, the carb is a waste of money.

Here's two others that help depending on application

street carb cfm = rpm x displacement / 3456 x 0.85

racing carb cfm = rpm x displacement / 3456 x 1.1

[CC69Rat]

Makes my head hurt ..

http://tgsperformance.com/holley.htm

Mostly what I know, I learned from my pop. I used to have a pretty hot LT1 / 0010 motor in a 69 Camaro years ago. We setup a 3310 for it with 70/76 and it was perfect for that motor. (355)

They'll all take some tweaking to get it spot on, but I have just had really good luck with the 3310. I think there is a 680cfm Street Avenger out there too? Might be something to look at. Dad has a 650cfm on his 390 GTA Fairlane. Cammed, factory manifolds, Flows, etc. It seems really close.

So, 680-750 with a little de-jetting .. just depends what you want. You could de-jet to 70 in the front and help a little with cruising / fuel mileage if you wanted to. The 76 jets in the secondaries would still hit like a Banshee though. (if the need arises)

[jason7698]

I live about 15 min. from quick fuel tech. I called them and Robby said 780cfm vac. sec,elect choke? What do you guys think?

[ricks71pu]

my 71 gmc is a 454 bored .30 over. running a 600 cfm w/o electric choke. i am in oregon, and not too cold too often. the 600 cfm is fine for daily driver.

[nomrlz]

the two most common mistakes in engine building is over cammed and over carbed

i think you could get away with a 600/650 but would gain a bit with a 750ish carb set right. since you were originally lookin to do a 496. i'd imagine you are plannin on flexin its muscle now and again

oh and an rpm or airgap would be a good all around intake

[ricks71pu]

oh yeah, edlebrock performer intake used.

[prostreetC-10]

Originally Posted by jason7698

So I decided not to go with the 496 but instead I got a great deal on a 454 bored .30 over and need to know what carb and intake to get she's going in a 1971 c10 weekend cruiser it will be bolted to a built th350..Here's what I know about the engine...

1981 454 bored .30 over
hypereutectic flat-top pistons w/ stock rods
stock bottom end
stock oval port heads
Lunati 543 lift 290 duration hyd. flat tappet cam

Engine is freshly machined with new cam bearings and heads gone through need carb and intake suggestions/advice...Thanks
Edit/Delete Message

Guess I'll just throw my 2 centos in. JUST going by the information provided, whoever built this motor put in WAY TOO BIG of a cam.....which goes along with what is written above about guys always picking too big of a cam and carb. If you go with a 750 3310, you will complete the mess.

That stock long block with flat tops is barely scratching the surface of 8:1 compression. You said is has stock oval heads, even if they are the early large oval, the cam is still too big. You possibly/probably have peanut ports which makes the problem even worse. You should be in the 260ish range on the duration with 270 being max. Your lift shouldn't be more than 500ish. Complement that with a stock converter and no gears, you are going to have a cam that sounds mean and is VERY sluggish down low. The last thing you want to do is throw too much fuel up top. I'd stay in the 600-650 cfm range. If you buy, you really need to jerk out that cam. It's just too big!!!!!

BTW....click on the videos in my signature. I'm running an early 454 with a small (270HR) roller cam. My car screams with a 650 DP. You will see that both carbs tested are bigger than a 650 but my car weighs over a 1,000 less than your truck, has a 3K stall and 4.20 gears. It still runs BEST with a 650.

[CC69Rat]

Jason -- are the valve covers on the motor now? Any way you can get one of them off? If you look under the rocker arms, there will be a casting number on your heads.

Let us know what heads you have. We can give you a better idea about compression, port sizes / flow, Prostreet has a good point. Can you get in touch with the person you bought the motor from? Do you know what compression / type pistons they put in the motor ?

He was talking about a stall converter too .. so that will help on the bottom.

[weircc]

im thinking sell that big block and get you a ls engine and get great HP and MPG just my opinion for what its worth

[CC69Rat]

tomato, TomAto .. Power = fuel and Fuel = power. Just depends on how you look at it. No disrespect for the LS crowd but don't count out the BB guys. It's all for the same reason. .. just a matter of preference.

I can remember the days of my 15mpg (highway) stock LS in my 2007 Silverado too .. what I'm saying is the LS motors are powerful in my opinion but they all take gas to make power.

[FrankieD]

Big blocks are nice just like a small block parts are plentyful and cheep.

[CC69Rat]

I aint afraid of an LS .. (kidding .. kidding)

I have an iron headded big block, yes .. but there are a few tricks up my sleeve too. Never count out an ole Big Block. It's all about the cash .. how big is your wallet ??

[weircc]

lol i have a 396 in my truck but just pulled the 468 from my camaro to make room for ls 6 speed reason being a new camaro has 426 hp and gets 25 mpg all day long

[CC69Rat]

Im just messin around. I know..

What did you pay for the ls6 / t56 though? Control module? Reflash ? Im not sure i could get 25 mpg out of it... just sayin

Good and bad in both options imo
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[nomrlz]

just pulled the 396 out of a junk truck for our 68 Camaro project.
now we're pulling the fairly fresh 283 out of the 66 truck to put an L33 in there

[weircc]

2000 in mtr n tranny new Camaro is 4500 p0unds 25 mph sh0ud be easy

[CC69Rat]

2000 for an ls6 and 6 speed? Wow ...smokin deal.
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[weircc]

craigsist

[jason7698]

The engine is what it is if it has peanut port heads oh well its brand new freshly machined (professional by the way) never had a drop of fluid in it new cam bearings,flat top pistons, new valves and heads gone through for less than 2k..Cant beat that peanut heads or not!