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Old 02-07-2005, 05:27 PM
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350 build upgrade cam

I bought a built 350/300HP engine w/2 bolt main. The specs on build sheet are:
73-79 block
heavy duty w/high pressure cam boss plug
Vatted-magged-certified for machining
Bored @ .030
Decked for squareness
Clevite cam bearings
Brass freeze plugs New galley plugs and front plus for cam tapped for high-pressure pump

Crank cast #442 ground @ .010x.010 and micro polished
Clevite main and rod bearings
Heavy duty re-sized rods w/ARP bolts- balanced
Hyper flat top 4 valve releif pistons Speed pro
Chrome Moly rings Speed Pro
Used harbonic balancer w/ new bolt
ROtating assembly balanced
Hyd cam and lifters Speed Pro
Cloyes true double roller timing set w/ lok-plate
Mellings hi-volume pump w/ new pickup and brace
ARP pump bolt and solid pump drive
Fuel pump rod w/ backing plate and bolts
New fuel pump w/ new bolts
Manley .065 wall pushrods
64cc 194x1.60 valves, Z28 springs, bronze guides PC seals, hard seats, 3-angle valve
Heads were squared-new loks
GM re-furbished glass beaded head bolts
GM steel stamped 1.5.1 rockers w/ grooved balls
Edelbrock Performer intake w/ Edelbrock 750 carb
All gaskets by FelPro
New long water pump w/ bolts and washer kit
Re-furbished spin-on GM oil filter adapter w/ bolts

Comp ratio @ 9.5.1
Don't have anyother specs on cam

This is in a 78 Chevy K10 SB pickup w/ 4-spd trans and electric cooling fan, Hedmann headers w/ Flowmaster mufflers, Accel HEI billet-proof distributor w/ Accel hi-volt coil. I recently acquired a pair of brand new GM vortec heads and was going to change the heads and cam. What is a good cam for this setup? It will be a daily driver, but I want it to haul balls. Any help or suggestions will be greatly appreciated.

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Old 02-08-2005, 08:43 AM
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cam upgrade

I would go with a cam that is only about 10-15 degrees duration at .050" , larger than your stock unit.
Comp Cams 255DEH, or XE250H, or Crane Cams Powermax H-150-2, or H-266-2, should fill the bill quite well. These are cams with lots of low and mid range grunt.
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Old 02-11-2005, 08:20 AM
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350 build upgrade cam

Thank you for the input. I was considering one of the cams you suggested and I will go with the 266. I'll let you know how it works out.
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Old 02-11-2005, 09:07 AM
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yw

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Old 02-11-2005, 09:44 AM
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combo

Piece of advice.
When posting combos.
Dispacement, heads, carb, intake, and stall is suffecient material for picking a cam. Brass frost plugs is unnecessary info.

Your carb is too big.
Your valves are too small.
Comp cams xe268h is fine especially since you don't seem to have any stall.
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Old 02-11-2005, 01:43 PM
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350 upgrade

Didnt notice that previously, but Dittos on the carb. Drop back to a 500-600 cfm vacuum secondary 4 bbl.
Since 99% of your driving will be at or below 3000 rpm, going to the smaller carb, 500 cfm, will be plenty sufficient, since this is a 5500 RPM strong engine, anyway. The smaller carb will enhance your low end driveability as well as improve your gas mileage when in cruise mode.
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Old 02-11-2005, 01:53 PM
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I agree on smaller carb, cept, if its an engine that might see 5500 RPMs, Id probably use a 600 personally.
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Old 02-11-2005, 02:47 PM
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basic thoughts on carburetion

There are a lot of people will say that the formula is invalid for finded the desired RPM, however I have noticed that according to the formula, with an engine in the 350 cubic inch neighborhood, that for every 1000 rpm desired, you need 100 cfm of carburetion.

IE: a 350 turning 5000 rpm requires 506 CFM
350 at 5500 RPM requires 557 CFM
350 at 6000 RPM requires 607 CFM

In years past, I have been told by carburetor gurus that if your CFM requirement falls in between the CFM's of given carburetors, to opt for the smaller of the two, in street appliations.
This does not mean that I would consider a 600 CFM carb as being excessive on a 5500 RPM engine.
Just food for thought.

At any rate, I definately would opt for a vacuum secondary carb, as then you can adjust the time that the secondaries begin to open and the point when they are wide open. This definately improves driveablility.
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Old 02-11-2005, 04:28 PM
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max we seem to think simialer...but not the same LOLI dont believe in the old CIXrpmXV.E. formula...never has worked for me. The whole V.E. concept gets thrown out the window in less than ideal situation anyway..such as a street car.
So I kinda made up my own formula based on what Ive found that works for me...alot of guys think its to conservative...but it works for me.
When someone tells me a 750 runs better on there mild 350 than a 600 its usually because theyve done little or no tuning, & a large carb is more forgiving out of the box than a smallish carb. the smallish carb generally needs to be richened up. I think the carb manufactures know this in advance that most people overcarb there engines.
the way I figure.. typical 355 going to 5500 needs 578.65 cfm... I generally up size LOL...or use a 570 or 575 & play with spacers.
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Old 02-13-2005, 08:36 AM
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350 build upgrade cam

Thank you all for your suggestions. First, I will try to limit info to required data. As to the carburation, I thought it was a bit excessive when I bought the engine so I bought a Holley 600 CFM and a rebuild kit and am going to rebuild and install it this week. I also found a new set of Dart 202 heads and think that I might use those instead of the vortecs with a Crane 266 cam as suggested earlier. Need to study it a little more.
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Old 02-13-2005, 08:52 AM
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I dont know...based on the rest of this engine, & the power band/RPM range your lookin at...the Vortecs may be the better bet
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Old 02-13-2005, 11:00 AM
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heads

I tend to agree with 454 on the heads. With your engine setup, I think you will have better overall performance with the smaller runners, the Dart heads will only be of any real advantage in the extreme upper end of your power curve, in my opinion.
I would rather run the slightly smaller head ports and have the better lower end performance,myself. The Vortecs will do about everything you want to do with your stump puller. And the 600 CFM carb is not at all out of line. I would set the vacuum spring to start opening your secondaries at about 2500 rpm with full opening around 5500 RPM.
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Old 02-13-2005, 07:29 PM
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350 build upgrade cam

I beleive you are right. After thinking and reading your comments I will stay with the vortec heads and pass up the Dart 202s. Thanks for your opinions.
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Old 02-13-2005, 07:50 PM
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youre welcome

Anytime! Go fast, but safely.
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Old 06-17-2006, 06:00 PM
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holley 600 some years was stock

a holley 600 was installed on some early model block v-8s. just thought i`d add that input. a road demon 625 is a decent carb for street and high performance. just my 2 cent worth to an old thread.
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