Vortec355

I have a 95 firebird that was originally a V6 and now it's a carburated 355. I want to go big block because the car weights over 3600 pounds and the only way to go fast in a heavy car is more cubes. I drive this car on the street and to the racetrack weekly. I'm going to go with a 540 big block with 12.5:1 compression for sure. I know the compression looks high but I will be running a big cam to bleed off the cylinder pressure, and I don't mind mixing fuel. I don't now if I should go with Canfield 350cc heads or Pro topline 360cc heads. I looked at flow numbers and saw the Canfields had higher mid lift flow numbers. The cam will be a Howards solid roller 712/715 278/288@.050 and 114 LSA. The cam may be a little smaller, but at least 700 lift and 270@.050. Any suggestion on heads, comments on combination.

Sandmann120

iTrader: (1)

The Canfield are a pretty good bagain, but I would also look into Dart heads. They can usually be purchased used for a good price. The cam looks like it should work, but be aware that big roller cams play hell with the rest of the valvetrain. I know of a guy near where I live who is selling a set of ProFiler heads, which would be killer on you setup.

pwr2w8

Is it just me, or do those heads seem a little big for a 540? I would think some 315cc AFR's would do just fine. I'm not sure if aftermarket heads have the problem at all, but cleaning up the bowl area under the valves usually makes the things come alive. IMHO but I think the 315's would work better.

Just my .02 cents.

Sandmann120

iTrader: (1)

I agree, I guess it just depends on his plans for this engine. How high do you plan to spin it? What kind of gearing, etc? A high revving big-cube motor, backed by a 'glide, in a lightweight car, would be killer. Although I would strongly suggest trying to lighten the car as well.

69chevy

i would have to say that the 315's would be a bit small on a 540 but if you plan on using the 350's, make sure you get a big enough cam to take advantage of the maximum lift of the springs close to its max potential. You could also lighten your car a bit to make it go faster. if you did, with the 540 that thing would fly! all of this is just a thought. Also, dart has the 335's which i have seen work really well on a 505 so just check those out but its all up to you in the end.

xxx

My 540 had Dart 345's and they seemed to work VERY well.

Keith

Check out the Merlin-X heads - 80cc chambers and 350cc ports. Might be an easy way to the 12.5:1 comp ratio. Something like 400cfm at peak if I remember right from the little blurb in the summit catalog..

Vortec355

I would probably spin the motor to 7500 tops. Right now I'm running 4:56's and a 700R4 tranny with 3500 stall. Right now I cruise at 2200 at 60 MPH and like to try to keep the overdrive. As far as gears go I think I might have to go to 3:73's. I'm running a 28X11.5 slick and it fits pretty tight. I do not want to tub the car.

Sandmann120

iTrader: (1)

Say goodbye to your 700R4 behind that 540. Just run a TH400 with those 3.73s, or maybe 4.10s. That big block, with a huge cam, will not like to cruise at anything much below 2500rpm. The cam will still be lugging. Let it spin.

69chevy

I've also been checking out this company at www.cferacing.com they have i think about 5 different sizes of cylinder heads and they flow pretty good with about a .750 cam with a max lift of .880. You can get them in jegs for 2800 for the pair for the 350cc version. i have been looking at these for when i build my motor up. just a thought.

MattG

I would go with AFR 357s. I have a 14:1 565ci (4.250 x 4.6) BBC with a set of the AFR 357s and a 286/296 .748/.748 cam. By the looks of the chassis dyno numbers it is in the 900-950 range.

We are still figuring the car out (3400lbs 72 Nova) but we have got a 9.95 @ 137mph so far. There is still lots more in it. I am sure when we get it all tweaked and I get used to driving it, that it will do 9.6s at ~141mph.

The AFR heads flowed 419 @ .800" as well so their advertised numbers are very close.

1fastWS6

iTrader: (3)

What were the chassis dyno numbers?

I'm running a 496 BBC in my 3100# 'bird with unported Canfield 310's, 13.5:1 comp, and a CamMotion solid roller with .800" lift and 278/290 @ .050. Car traps 113 in the 1/8th and 145 in the 1/4. I spin the motor -conservatively- to 7k, but it should be making power to 8k according to CamMotion.

I'm no expert by any means, but I'd think on 540" a 350cc intake port would be fine on a 7k+ rpm motor. I like the Dart's but Brodix, Canfield and AFR all are nice.

68maro

i would think your #'s are off my motor made 953hp on the dyno and the car weighs 3650. my first pass it went 9.65 at 143 on a 1.61 60ft justblowing away the tires. i want 8.90's 9.0's out of it which should be easy because by the third pass it went 6.01 in the 1/8 still spinning and with no timing. now that the chassis is straight and some timing back in it 5.80's should not be a problem. and plus this is a nitrous motor not designed to run n/a