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496 stroker BBC ???

13K views 12 replies 7 participants last post by  Derkyb 
#1 ·
Aight, so here is the deal. Im a 20 year old kid who is finally making enough money to build a serious street BBC. I have a 2 bolt 90 454 truck engine. I plan on adding.

496 stroker kit from speedomotive
Lunati Vooddo cam adv. dur. 276/284, 233/241 dur. @.050, 110 LSA
AFR Magnum 305CC cylinder heads, as cast, no porting flow .335/.251@500, .363/.276@600
Victor 454-R Intake
1.7 ratio jegs roller rockers
850 cfm speed demon carb.
10.17 compression

anybody mind running a desktop dyno for me?
Suggestions on component selections?

plan on running pump gas/ maybe even with a lil octane booster, want to avoid running race gas...

going in a 72 nova with 3.73 gears, and a 2500 converter,
 
#3 · (Edited)
You think he will have trouble with 10.17:1 compression with aluminum heads? I had a 355 with iron vortec heads and dual valve relief flat tops that was right at 10:1. That ran fine on premium (92 octane) with a smaller cam than the one he is using (XE268H). Either way, I agree that a larger cam would be beneficial. A 496 is a large motor, even something in the low 240's at .050 would be a nice street cam. It is a little hard to say exactly where the motor will "start" making power, but with the cam you are using, I think a 2500 stall would be adequate in a 454. The fact that it is a 496 will bring the powerband down, requiring less stall. I would see what the other guys think, and also call AFR to see what they say along with lunati. Also, I would think about the Performer RPM air gap rather than the Victor. Think about matching your parts rather than concerning yourself with the size of the motor. The 305cc heads are recommended for 2500-6800 RPM, your cam is going to be ~2300-6300 an the Performer is 1500-6500 RPM (this is all based on a ~454 cubic inch motor each part will proportionally lower in a 496). If you go with a larger cam, the victor may be a good idea, but I would not think that would be the case unless you are going to be in the upper 240's at .050 range at a minimum.

Check this out. It is a 512 with the 315cc heads and a much larger cam than what you are looking at (254 260@.050) It is making almost 700 ft lbs at ~5000 RPM. Yours will be at a lower RPM even with a cam in the low 240's at .050. From what I understand, in a street car, it is best to have the stall come in ~1500 RPM before max torque in a motor like this. I think you should be able to get away with something more like 2000 RPM under max torque with the amount of low RPM torque your motor will be making. I would see what the other guys say, this just makes sense to me.
http://airflowresearch.com/articles/article52/A-P1.htm


Adam
 
#4 ·
That is going to be one helluva street motor your building. Hope you have the budget for the trans and rear it will take to hold that torque, not to mention finding traction. I built my 496 for street/strip stock heads, 244 cam, demon, edelbrock it made 520hp/596lbft on the dyno and is more than a hand full in a 70 chevelle.
 
#7 ·
Derkyb, what are the casting numbers of your heads; have you had any porting or larger valves installed? I am in the process of building a 496 with a set of fully ported 2.19 1.88 valve 049 heads with a solid roller (248 254 @.050). I just wanted to compare mine to yours. I was hoping for ~600 hp and ~600 ft lbs. Also what RPM were each of your max numbers at?

Thanks,
Adam
 
#8 ·
I'm running the 781's no port work or polishing done, just added 2:19's. Peak numbers were 596lbft at 3600 and 520hp @5000 but this is with some junky homemade headers(see gallery) I installed hooker super comps after dyno run so I figure for another 10-20hp.
 
#11 ·
The Cam should be spot on...., it is recommended for 10:1 compresion and a 3.73 gears... and has an rpm range of 2200-6400, the Victor Jr. is recommened by AFR for the heads... only changes I am thinking about is a holley 850 double pumper instead of the speed demon... a buddy has the 750 speed demon on a 350 with vortec heads and a street cam, and it is doing the same thing Big Trey stated, bogging horribly off the line, and I know thats more than enough carb for the engine, personally im thinking they may just be junk
 
#12 ·
Holleys, Demons, Edelbrocks, Carters..........some of them "work" out of the box, some don't. Expect to properly tune the carburetor for your engine and you won't be disappointed. There's no way for them to know what the carburetor is going to be used for when it's being built. If Holley's base calibration worked for your engine and Demon's didn't it doesn't mean the Demon's junk. It means you got some work to do.

Even if one of them does "work" out of the box, it doesn't mean that it's properly calibrated for the engine. You just got lucky.


Larry
 
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