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Old 02-06-2012, 11:14 AM
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SBC questions?

Here is what I have in my 71 C10 with a 350 turbo tranny....
1995 5.7 tbi crate enging around 6000 miles weekend driver no drag strip
Block: Cast iron, 2-bolt main, 1-piece rear main seal
Connecting Rods: Powdered Metal Connecting Rods
Pistons: Dished Hypereutectic
Compression Ratio: 9.4:1
Oil Pump: High-Volume Oil Pump
Timing Chain: Morse link-type
Camshaft: Lunati 07101LK-
# Advertised Duration (Int/Exh): 275/275
# Duration @ .050 (Int/Exh): 225/225
# Gross Valve Lift (Int/Exh): .477/.477
# LSA/ICL: 108/104
# RPM Range: 1800-5800
Cylinder Heads: Dart, Iron Eagle S/S Cast Iron Chev SB Head, 165/67cc 1.94/1.50 stainless valves.
I have installed an edlebrock 600 cfm carb and performer intake with hooker procomp headers and flow master dual exhaust. Truck sounds awesome but I was looking for better performance is there any glaring issues with this set-up should I go with a bigger carb? Lastly would anyone take a stab at what hp I'm making?...Thanks any info/advice would be appreciated!

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Old 02-06-2012, 02:26 PM
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Quote:
Originally Posted by bigj7698
Here is what I have in my 71 C10 with a 350 turbo tranny....
1995 5.7 tbi crate enging around 6000 miles weekend driver no drag strip
Block: Cast iron, 2-bolt main, 1-piece rear main seal
Connecting Rods: Powdered Metal Connecting Rods
Pistons: Dished Hypereutectic
Compression Ratio: 9.4:1
Oil Pump: High-Volume Oil Pump
Timing Chain: Morse link-type
Camshaft: Lunati 07101LK-
# Advertised Duration (Int/Exh): 275/275
# Duration @ .050 (Int/Exh): 225/225
# Gross Valve Lift (Int/Exh): .477/.477
# LSA/ICL: 108/104
# RPM Range: 1800-5800
Cylinder Heads: Dart, Iron Eagle S/S Cast Iron Chev SB Head, 165/67cc 1.94/1.50 stainless valves.
I have installed an edlebrock 600 cfm carb and performer intake with hooker procomp headers and flow master dual exhaust. Truck sounds awesome but I was looking for better performance is there any glaring issues with this set-up should I go with a bigger carb? Lastly would anyone take a stab at what hp I'm making?...Thanks any info/advice would be appreciated!
The Iron Eagle head is made to be ported, as it comes the flow isn't what it could be. For a street driver I'd be somewhat conservative and limit the porting to the valve pocket. You can do this yourself with an electric die grinder and a carbide cutter selection. I don't recommend an air grinder as it takes a darn good (read that expensive) air compressor to adequately feed them as they eat a lot of CFM. You have to exercise care to avoid the seats, wrap 'em up really good in tape and go slowly. This head also likes 1.6 rockers and back cut valves. The latter will work well with this moderate lift cam giving more flow in the mid lift zone where the 1.6 rocker adds flow over the top of the lobe, a good combo that lets you improve flow over most of the lift profile.

The 600 CFM carb is small for the cam, bigger cams like bigger carbs. But again for a street engine some balance needs to be struck between the needs of cruise and that of WOT. A good choice here is an old Holley spread bore, a Q-Jet, or the Edlebrock/Carter in the zone of 750 CFM.

I'm concerned about the pistons, most of these crate motors come with a circular dish piston which regardless of compression results in a lazy burn everywhere except at WOT. A flat top is a better solution though with 64 cc heads the compressionmight be high. Let me ask how this gets to 9.4 with a dish piston? Just the numbers of gasket thickness, head deck clearance, and volume of dish in the piston will do. If the piston has a D dish a lot of your squish/quench issues are solved.

There is a lot of talk about the squish/quench distance these days. This is important to the speed of the burn and to detonation suppression. Typically for a street engine the distance between the piston crown and head squish/quench step is optimally .040 inch. I'll take .060 max as being minimally acceptable and .035 the minimum if you're running a tight piston wall clearance such that when it rocks over on thrust it can't move enough to kiss the head. For a race engine that can be sliced thinner when your salary is on the line, but for a street engine such a meeting will take a lot of paydays to recover from.

We need to run a Dynamic Compression Ratio for your cam which means getting out the timing card to look up where events occur, especially when the intake closes.

Getting the Squish/Quench and the DCR correct adds a lot to the bottom through midrange power without having to add gears to wind the motor over that point to find power. This will improve street performance and mileage.

Bogie
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Old 02-06-2012, 02:45 PM
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that crate is a 96-02 vortec crate.. 9.4 to one with vortec heads 64 cc
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Old 02-06-2012, 02:49 PM
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Actually its a 86-95 tbi engine and came with swirl port heads thats the reason I put the dart casts on.
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Old 02-06-2012, 02:58 PM
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same parts different heads
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Old 02-06-2012, 04:21 PM
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How much of a difference will the 750cfm carb make?
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Old 02-06-2012, 04:28 PM
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Quote:
Originally Posted by bigj7698
Actually its a 86-95 tbi engine and came with swirl port heads thats the reason I put the dart casts on.
What is the rear gear ratio? The converter stock, or ?

I'd be using more carb, Holley 3310, for instance and a RPM (not air gap) intake. The distributor has to have a performance curve in it!
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Old 02-06-2012, 04:35 PM
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Not sure on the gear ratio but will find out the converter is stock. Being new to this what should I do as far as the distributor goes? Will the carb make a big difference?
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Old 02-06-2012, 05:09 PM
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Quote:
Originally Posted by cobalt327
What is the rear gear ratio? The converter stock, or ?

I'd be using more carb, Holley 3310, for instance and a RPM (not air gap) intake. The distributor has to have a performance curve in it!

750 vac sen on a mild 350?

may I ask why when most 350's don't need more than 550 cfm
650 more than enough.. torque moves you...
ya the 750 will breath better at 7000rpm ..he did say truck
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Old 02-06-2012, 05:54 PM
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Quote:
Originally Posted by bigj7698
Not sure on the gear ratio but will find out the converter is stock. Being new to this what should I do as far as the distributor goes? Will the carb make a big difference?
First things first.

Your '71 would have had a points-type distributor originally. It used a resistor wire to reduce the voltage to the coil when the key is in the "Run" position. If you have an HEI distributor now, it needs full battery current even in the Run position. So w/the HEI you need to determine w/a volt meter what the reading is at the coil w/the engine off and the key in the Run position. If you're still running points, oh well...

If that checks out then the timing curve can be worked on.
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Old 02-06-2012, 06:14 PM
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Quote:
Originally Posted by stich626
same parts different heads
No roller cam, either.
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Old 02-06-2012, 06:25 PM
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The guy who installed the cam and heads also tuned it he said the timing was set to get the most out of the engine and still idle good. I guess the next move for me would be decide on a carb since the 600cfm is to small..Thanks guys
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Old 02-06-2012, 06:28 PM
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Quote:
Originally Posted by cobalt327
No roller cam, either.
well, the cam doesn't give you the static compression either,,
but the same pistons, and head cc will
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Old 02-06-2012, 07:25 PM
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Quote:
Originally Posted by bigj7698
The guy who installed the cam and heads also tuned it he said the timing was set to get the most out of the engine and still idle good. I guess the next move for me would be decide on a carb since the 600cfm is to small..Thanks guys
One man's opinion of the best timing may not actually be the best, w/all due respect to whoever tuned it.

Just to be on the safe side, see what the initial and total timing is. No need to change carbs or anything else until you do that, and if you have an HEI ignition, you still need to see what the voltage is at the coil w/the key in the "ON" or "RUN" position.

And you need to see what the rear gear ratio is as well. That alone can make the engine feel sluggish.
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Old 02-06-2012, 08:13 PM
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3.08
3.73
4.11
my bets on the first one.. just like my long bed
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