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Discussion Starter · #1 ·
Wassup, my name is rich. This is my first bulletin and also first engine. I have a gen V 454 and its .60 over. Got the crank just need help with good high comp. Pistons, heads and cam... Lookin to hit that 600 mark. I'm open to suggestions and any advice. I need help
 

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big heads, big solid roller, big carb, big exhaust, and high compression.

320cc+ ports, 260 degree at 0.050" with 0.650+ lift

950+ cfm holley on a victor jr. intake

2 inch headers with dual 3 inch pipe.

11:1 cr.
 

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Discussion Starter · #3 ·
see, from what I've seen, heard and read, going close to 11:1 compm isn't good for pump gas.. A lot say its bad but few say its ok... I'm going to take the car to the strip of course to see what nunbers I can make but its mostly gonna be a weekend toy
 

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when figuring compression with pump gas the cam timing must be considered. a big cam has a very late intake closing point which decreasing the length of the compression stroke. This lowers cylinder pressure. The term is called dynamic compression ratio.

I run 11:1 cr in a sbc with a cam with 292 degrees advertised (244 at 0.050") and run pump gas without any issues. Even use iron heads.

BBC's tolerate less compression ratio than a sbc but a 260 degree at 0.050" cam will be around 310 or 320 degrees advertised which is very long. a cam like this with aluminum heads will have no issues with 93 octane.
 

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Discussion Starter · #5 ·
i was thinkin of running these 119cc afr 325 heads with sum srp pistons which say the comp. ratio should be round 10.2:1... so f i run a big cam ur saying its gonna lower the ratio right? if this is true basically just go with a little higher compression pistons??
 

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Yes, that is the term (bleeding off compression).

however, most people think that valve overlap bleeds off compression, which is wrong. The engine isn't try to build compression during that part of the cycle so overlap has nothing to do with that.

The intake valve closing point is where compression is bleed off. As the piston is rising in the bore to compress the gas/air charge, the intake valve is open. And on long duration cams, the piston rises quite a bit before the valve closes so this cuts short the compression stroke. A short stroke captures less air and this lowers cylinder pressure.

A 8:1 cr engine with a small cam can have more cylinder pressure than a 10:1 engine with a really big cam. Dynamic compression ratio is critical in engine setup.
 

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It seems like different calculators have different sets of values. I have used the one on Keith Black Pistons site for several years. Feedback from numerous builds has shown that a DCR of 8.0 to 8.3 is a good pump gas motor target on that particular calculator.

Here, for instance, is a 496 build from my DynoSim that made 8.156:1 DCR on the KB calculator.....
Canfield 305cc heads, 2.300"/1.900"
RPM intake, 1000 CFM carb, large tube headers, 6.335" rods.
Comp hydraulic roller 11-460-8, 0.648"/0.648", 244*/244*
RPM HP TQ
2000 168 441
2500 215 452
3000 275 482
3500 359 539
4000 443 581
4500 521 608
5000 587 617
5500 623 594
6000 630 552
6500 609 492
Substituting an 850 carb still makes 616/608.
Just a heads-up for you. Pat McCarthy, a highly-respected BBC engine builder on another forum will only use a flat tappet cam in a customer build after the customer has been warned that the chances are good that the motor will roach the cam. Seems that a BBC is worse about this than a SBC.
 

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Well I skipped reading the posts because I know you can get there using the peanut port heads, so like your goal is not too hard to achieve with regular old parts. Don't let people tell you you need some R ports or after market new heads. Serious on the head issue. Check Google for some BBC head shootout thingy from some time last year in a car rag. :thumbup:
 

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Discussion Starter · #13 ·
Yea After U Told Me To Research It That Was One Of The Sites I Found... It's Alittle Over My Head But I Want To Learn So Its Kool. Im Also Gonna Go To My Machine Shop Monday And Talk To Help So He Can Also Help Me Understand.. This I Smy First Motor So All The Info You've Given Sofar Have Been Really Helpful. I Apreciate It Big Time.. Im Jujst Lookin At Anway To Reach That 600 Or 600+ Mark Out This Block... If Theres Any Thing Else U Think That Can Help Me Hit Me Anytime Or Reply To The Post But I'll Keep U Updated On Prgress And Questions... Just Lookin For That Perfect Combo But Also Trying To Learn And Understand What Exactly Makes It That Oerfect Combo....thanks
 

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O.K. the gen 5 engine cam with the peanut head and bee hive valve springs.
these heads are useable if yu want to spend about 1000 to 1500 in port work and new valves. however when using an aluminum head the engine runs one whole point cooler on you cr without losing horsepower. example with a iron head and a big cam, as it heats up and your at 11.1 if your timing is off a little it can put you into detonation due to the heat, and the outcome BOOM.
But with aluminum heads the heat factors are different. same example with aluminum heads and 11.1 you heat factor is 10.1 but your engine is stillrunning at 11.1. With less heat less chance of detonation. 11.1 on a big block is wright at that point.

My opinion with what you want is a descent steel crank. not high dollar and not junk, somewhere in middle. a set of h beam rods and a set of forged pistons set up like this.


aluminum heads- flow [email protected] 600 lift
crank-steel
rods- h beam
cam- street/strip profile around 240 adv. duration and 600 lift with 1.7 rockers
rockers- steel with roller tip. no need for aluminum if not a all out racer.
timing chain- a good double roller, pick a name brand, they have closer tolerances.
intake- air gap, good mid range streetable or a single plane like a victor series.
carb- holley, quick fuel or demon 850 dual feed double pump
dist- stock with spring kit and good internal components
headers- large tube

this is my recipe for 600+ out of a bbc. many companys like speed-o-motive, scat, eagle sell rotating assemblies for a 496, it's common.
good luck
 
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