Hi everyone,
I've been doing a project 1971 custom chevy c10.  I've managed to tear the truck completely apart, a complete frame off restoration.  I've done all sorts of custom work to it, but as I'm going to college, I've put the project on hiatus until the spring comes, as financially it's hard to do both at once! Anyways, I got a very good friend of mine (who's been a mechanic for 30 years or so) to redo my engine.  He built it to spec and correctly, he just was not sure about what kind of power it would produce, if anyone could just take a look over the facts, and give me an estimate I greatly appreciate it!

Block : 350 chevy 4 bolt main
Heads : '96 Stock Vortech
Bore : 60" over, ( was done by the previous owner )
Stroke : Believe it's stock
Crank : Believe it's stock
Cam : Edelbrock Hydraulic Flat Tappet Style, Advertised Duration 278/288, Lift .420/.442
Carb : Edelbrock Performer, 4 barrel, 600 cfm electric
Timing Chain : Edelbrock True Rolling timing Chain
Intake : Edelbrock Aluminum Dual Plane Vortech Intake
Intake: Edelbrock Air Cleaner w/ K & N Filter
Pistons : 60" over flat ( by previous owner, unsure of brand )
Headers : Summit Racing Ceramic Coated Headers, 1 & 5/8ths Primary, 3" collecter
Exhaust : 3" True Duals from headers, 3" Flowmaster Super40's with 3" center & offset

In a day or two, I will have my website finished showing the build process of the truck, start to near finish ( its not done yet! ) for anyone who is interseted, it will be in a new post. Thanks for looking and any help!

I would guess 345-355 Hp making a ton of assumptions.

That sounds reasonable, Any ideas on torque? I was guessing 375 ft pds of torque and 350-360 hp personally

With the cam and carb this engine will deliver somewhere in the range of 300-350 ponies with about 350 to 375 ft pounds of torque.

A larger carb would provide more top end, 600 CFM is marginally small for this engine with a dual plane manifold, so I'd expect power to peak closer to 300 than 350. But there's potential that a 650-750 cfm carb will unlock.

I'm not a fan of the Edlebrock air cleaner. They may look cool; but cold air being sucked into the engine makes power and reduces detonation tendencies. I much rather see a factory style "box" aircleaner housing attached to an air source behind the grill or off the cowl vent. A K&N on the inside of the "box" is fine, but keep in mind that most street engines never see the kind of RPM that taxes the capability of a factory filter. For every 10 degree drop in the carb's inlet air temp you pick up 1% on horsepower. So tapping 80 degree air behind the grill instead of 180 degree air under the hood is worth a 10% gain in pony power. 

Bogie

I'm not sure how much power the D-dish pistons make, but with a cam swap, look what ballpark you'd be in ...

http://www.chevyhiperformance.com/howto/47075/

(390 hp and 426 lb-ft , if you don't feel like clicking the link.)

It isn't so much that "D" dish pistons make power as much as they help you keep from loosing it to detonation or preignition. The "D" dish makes for a much more energetic squish as the piston closes on TDC than a full dish or domed piston does. The turbulance imparted to the mixture by a "D" dish or flat top speeds the burn thus reducing the tendency for the mixture to explode. The "D" dish or flat top also are effective in quenching out the extreme temperature build up of the late part of the burn, again helping prevent the last of the mixture from exploding.

This comes around from initally helping supress detonation such that in the longer haul it  holds chamber temps down such that preignition is also less likely to become a factor.

Both detonation and pre ignition significantly reduce power and they both are mighty hard on expensive parts, melting or blowing holes in pistons. They can apply enough force to the rod to break it, force oil out of the bearings, actually crush the rod bearing, or pound a flat spot into the crank. That's how bad these characters can be.

Bogie

Thanks for that clarification, Bogie.

That being said, the 406 I've been building on paper for a while has 8.75 : 1, and D dish pistons sitting under vortec heads. The compression number came from googling and reading articles that told me that was where the comp. ratio needed to be to run safely on 87 octane.

In your valued opinion, if I run 8.75 : 1 with regular dished pistons versus D-dished pistons, would there be any difference in the performance characteristics? Is a slightly higher comp. ratio safe for 87 octane with the D dish piston; or do I need a slightly lower comp. ratio with a standard dish?

I realize (I think) that more compression makes more power/torque, and I want to maximize power and torque with the highest compression ratio possible, while still safely running 87 octane.

I would greatly appreciate your two cents on this subject, as I am going to start the 406's machine work with my tax return check.

Thanks.

Ok, let me rephrase my question.

In a relatively heavy (82 C10 Blazer), with a 406, vortec heads, very mild cam on a 112 lsa... assuming .040 piston to head deck height. 

what is the maximum compression ratio I can safely run with 87 octane with:

-D dish pistons

-standard dish pistons

Is there enough  information out there for a real answer, or just a "safe" guess?

The Vortec head uses (or returned to) the Ricardo carodid combustion chamber which as wedge chamber go is very effective and efficient. To show you how cheap the auto manufacturers can be hardly anybody used it eventhough its benefits have been known since the late 1920's. But everybody was more interested in saveing the few pennies the beak cost. Ford started using it in 1954 on the Y block V8 and dropped after 1955. The decision is that you can spend a few bucks more on a better grade fuel rather than the manufacturers spending an additional dime on each cylinder head made. The chamber showed up again in the early 1960s on the Gurney Westlake Ford head that went to Indy, SCCA, and lots of Ford powered European racers spun off the GT-40. These chambers popped up again when in the early 1970's Doug Roe revamped the Vega factory head to make a competitive Midget and SCCA powerplant out of the thing. Now of course since the mid 1990s all this technology has been rediscovered and is now the rage in "Fastburn" chamber design. This is a good thing, one just wonders whay it takes the major manufacturers so long to use what's been known for generations already.

The Vortec head is intended to use regular grade unleaded with a static compression of about 9 to 1 or a bit higher. However, keep in mind that's with sequential fuel injection an engine that's carbureted or uses TBI will be a bit less tolerant of that compression when operated with a 200 degree thermostat and typical factory high rato rear ends. But other things come into play that let you game the compression a bit vis-a-vis the advantages of timed fuel injection. You can gain some tolerance back by running a richer mixture, sourcing cold air for the intake, using a cooler thermostat of 160 to 180 degrees.

The cam dimension you sight is Lobe Seperation Angle which is only one consideration. At 112 degrees it tells you that the overlap will prove to be mild, but this still needs to be considered with duration, lift at the valve and the intake closing point. Also, the aggressivness of the lobe or its rate of lift needs to be considered as does the rocker ratio. In terms of rocker ratio effects if a 1.6 is used on a small block cam instead of the factory 1.5 ratio, the effect of the 1.6 is to make the valve behave as if the cam has a more aggressive contour. That's to say compared to a 1.5 rocker the 1.6 will exhibit at the valve more lift both faster per degree but also in total. So a 1.6 makes the engine run like it has more cam duration, lift, and overlap.

The wilder the cam or really the motion at the valve, the more compression is needed to overcome low speed reversion effects. Reversion effects are where either there is insufficent intake flow velocity  to overcome exhaust dilution during overlap or reverse piston pumping with a late closing intake. Basically the following table tells you how much static compression needs to be adjusted for where the cam closes the intake with regard to piston position.

Degrees ABDC                                               Lost Compression Ratio

20                                                                              1.2

30                                                                               2.2

40                                                                               3.1

50                                                                               4.1

60                                                                               4.9

This is based on starting with a ratio of 8.0 to 1. These numbers become additive to that based upon the degree at which the valve closes in term of piston position After Bottom Dead Center.  So you can see a really hot cam closing at 60 degrees ABDC requires a compression ratio of about 12 to 1.

I would expect that your ratio of 8.75 should be good with 87 octane.

Bogie

Thank you for that info, Bogie.

The two cams I was recommended by Crane and Comp's phone tech lines are:

http://www.compcams.com/Technical/Search/CamDetails.asp?PartNumber=12-249-4

http://www.cranecams.com/index.php?show=browseParts&action=partSpec&partNumber=113902&lvl=2&prt=5

Both of them are quite mild, just a little over stock specs it seems. (What would your preference of the two be? or perhaps a pick of your own? ) I will be running a 160* thermostat with an AC Delco aluminum replacement radiator, so hopefully temps won't rise much over 160. (perhaps a bit higher with the A/C running)

I live in central Fl (no smog testing), so the altitude is essentially sea level. The summer temps are often around 95* with high humidity.

-not sure if I mentioned it earlier, but the intake will be a Performer RPM vortec, and carb is/will be a vac sec. Holley 600 (it's what I have) .

If you were building this motor for your daily driver, designed for fuel mileage, yet torque to tow 5,000lbs occasionally... would you pay the extra money to have 32cc D-dish pistons custom made for 5.565 rods, or be satisfied with a full dished piston?

Actually it is probably more like only 290 horse. I plugged the numbers you gave me, and a few generals like intake runner size on your heads, in to a virtual engine calculator, and it says about 286 hp and 395 ft lbs torque. top end rpm is about 5000, but it gets up and boogies from a dead stop right?  

I mean whats in your motor currently...