Need some blown big block C3 advice
05-22-2017, 08:01 PM
#1
Need some blown big block C3 advice
Anybody have any experience/tips for me? Ever since I was a kid (I'll be 50 this year) I've always wanted a blown big block C3 and it's finally about to become a reality. Last year I bought a 69 with a worn out non original small block 350. I built a mild 454 for it and installed it last winter. It's fun but it's not fast enough and it's not my dream motor anyway so now I'm building an 8-71 blown 454 for it. This motor is going to be much heavier than the 454 that's in it right now, the 8-71 setup weighs damn near 200 pounds. The motor is all iron, it doesn't have aluminum heads and I don't want to spend a few grand on a set of heads just to make the motor lighter, I'd rather just put in stiffer front springs to support the extra weight. What front springs do I need to get for it? The big block C3 springs that I bought from zip when I converted the car to a big block won't be strong enough to support an additional 200 pounds and I can't find any info on heavier springs. Also, what should I do about the driveshaft, half shafts, and U-joints? Where should I get heavy duty driveline stuff from? What parts do you recommend? I'm not going to boost the hell out of it and try to squeeze every last horsepower out it by the way. Its mainly going to be a street car with street tires, not an all out drag strip monster with big sticky slicks. I have no problems with sacrificing some horsepower in exchange for streetability and reliability. Anyway, what about the cooling system, what radiator and fan setup is available that will keep it cool? Is there anybody out there with a blown big block C3 that can tell me what kind of issues I'll run into and what to do about them?
05-23-2017, 11:05 PM
#3
Racer
Those springs are fine, I'll bet.
I went with a Dennys driveshaft, DeWitt radiator and fans, and solid rear axle so dunno about half shafts, etc. If not running sticky tires, the rear may hold up.
200 lbs is too much. The manifold will be lighter than cast iron factory and the blower is around 100lbs.
I went with a Dennys driveshaft, DeWitt radiator and fans, and solid rear axle so dunno about half shafts, etc. If not running sticky tires, the rear may hold up.
200 lbs is too much. The manifold will be lighter than cast iron factory and the blower is around 100lbs.
Last edited by 97C5; 05-23-2017 at 11:09 PM.
05-23-2017, 11:08 PM
#4
Le Mans Master
I can't help you on the blower motor questions....but you can get the HD rear end parts from Tom's Differentials, as well as Tracdogg or Gary Ramadie. For a 700hp+, stick car, I would put the best rear end stuff in there you can, especially if you're planning to run drag radials.
Differential
On a budget with regular street tires, you can get some nice 3" halfshafts and solid Spicer ujoints, as well as a upgraded 2.5" driveshaft from Ft Wayne Clutch & Driveline.....They are good quality stuff and much cheaper then the vette vendors offer. I've been running 10s on this stuff for years. Ofcourse all of the vette vendors offer similar stuff. Definitely stick with solid Spicer ujoints on everything.
Cooling:
Dewitts radiator with dual spal fan kit. If the dual Spals won't keep it cool at idle, a '93-98 Lincoln MKVIII fan will. For the lincoln MKVIII fan, you'll need a 140 amp alternator, upgraded wiring and good relays.
Springs
With stock suspension, your only option is to get the F41 HD springs. All of the vette vendors will sell them. Otherwise do the VBP front leaf swap and get a STIFF spring. I'd call VBP and ask their advice.
Differential
On a budget with regular street tires, you can get some nice 3" halfshafts and solid Spicer ujoints, as well as a upgraded 2.5" driveshaft from Ft Wayne Clutch & Driveline.....They are good quality stuff and much cheaper then the vette vendors offer. I've been running 10s on this stuff for years. Ofcourse all of the vette vendors offer similar stuff. Definitely stick with solid Spicer ujoints on everything.
Cooling:
Dewitts radiator with dual spal fan kit. If the dual Spals won't keep it cool at idle, a '93-98 Lincoln MKVIII fan will. For the lincoln MKVIII fan, you'll need a 140 amp alternator, upgraded wiring and good relays.
Springs
With stock suspension, your only option is to get the F41 HD springs. All of the vette vendors will sell them. Otherwise do the VBP front leaf swap and get a STIFF spring. I'd call VBP and ask their advice.
Last edited by ajrothm; 05-23-2017 at 11:09 PM.
05-23-2017, 11:22 PM
#5
Le Mans Master
No one has jumped in so I'll add my 2 cents.
1st the added weight. I had 550 pound springs on my 427. I though they were too soft for me. I didn't see anything heaver so I went with coil overs and a 600 pound spring. They are easy to change out to a stiffer spring or see if the shock adjust is enough.
2nd Cooling, Top notch radiator, water pump and fan clutch should keep everything in range.
3rd Drive-train, Street tires will save you here, but upgrading would be a wise idea. Super 10 or 12 bolt would be wise. Stronger half shafts and drive shaft. dennys driveshaft and toms differentials.
Don't forget the transmission too.
I've built a few blown cars. Timing, compression and cam selection are important.
1st the added weight. I had 550 pound springs on my 427. I though they were too soft for me. I didn't see anything heaver so I went with coil overs and a 600 pound spring. They are easy to change out to a stiffer spring or see if the shock adjust is enough.
2nd Cooling, Top notch radiator, water pump and fan clutch should keep everything in range.
3rd Drive-train, Street tires will save you here, but upgrading would be a wise idea. Super 10 or 12 bolt would be wise. Stronger half shafts and drive shaft. dennys driveshaft and toms differentials.
Don't forget the transmission too.
I've built a few blown cars. Timing, compression and cam selection are important.
05-24-2017, 04:28 PM
#8
Thanks for the replies so far, every little bit of info helps. I forgot to mention the trans in the car, it's a turbo 400 w/a shift kit. I'm not gonna go with a high stall converter because it's not really needed for what I want to do with the car (99% street driven with an occasional run down the strip). I have no use for a high stall converter. It's not gonna have a lumpy race cam either, I want one with a good idle. Speaking of which, the engine is a gen 6 454, does anybody know what would be a good hydraulic roller cam for it? All of the hydraulic roller cams that are made for supercharger use that I've been able to find so far say they have a rough idle which is what I don't want. Does anybody make a gen 6 hydraulic roller cam for use with a blower that has a good idle?
05-24-2017, 04:58 PM
#9
I built a 406 small block with a 6-71. It never fails to make people invent new expletives when they drive it. Upping the formula to a BB and 8-71 will be amazing. Figuring that hood clearance will be solved with a saw I'd consider a tall deck if you can swing the budget. Of course it snow ***** from there (extra head bolts, bla bla bla). Good luck with a great project.
05-24-2017, 05:16 PM
#10
Drifting
Anybody have any experience/tips for me? Ever since I was a kid (I'll be 50 this year) I've always wanted a blown big block C3 and it's finally about to become a reality. Last year I bought a 69 with a worn out non original small block 350. I built a mild 454 for it and installed it last winter. It's fun but it's not fast enough and it's not my dream motor anyway so now I'm building an 8-71 blown 454 for it. This motor is going to be much heavier than the 454 that's in it right now, the 8-71 setup weighs damn near 200 pounds. The motor is all iron, it doesn't have aluminum heads and I don't want to spend a few grand on a set of heads just to make the motor lighter, I'd rather just put in stiffer front springs to support the extra weight. What front springs do I need to get for it? The big block C3 springs that I bought from zip when I converted the car to a big block won't be strong enough to support an additional 200 pounds and I can't find any info on heavier springs. Also, what should I do about the driveshaft, half shafts, and U-joints? Where should I get heavy duty driveline stuff from? What parts do you recommend? I'm not going to boost the hell out of it and try to squeeze every last horsepower out it by the way. Its mainly going to be a street car with street tires, not an all out drag strip monster with big sticky slicks. I have no problems with sacrificing some horsepower in exchange for streetability and reliability. Anyway, what about the cooling system, what radiator and fan setup is available that will keep it cool? Is there anybody out there with a blown big block C3 that can tell me what kind of issues I'll run into and what to do about them?
The aluminum heads do more than just weight. They help cool the engine, they are much more forgiving on tuning than an iron head, and if the tune is missed and you torch an iron head it is junk. Aluminum you weld it back and mill it flat. I would HIGHLY recommend aluminum heads over iron.
05-24-2017, 06:20 PM
#11
Racer
My 540 has 267 degrees @ .050 intake duration and idles fine for comparison. Was actually "disappointed."
Should consider engine bay space, accessories, clearance to firewall (I had to notch my valve cover to clear with a short deck), header availability/fitment for a tall deck but is an option. I thought about a tall deck to move up to a 632 but it introduces a lot of other issues.
Should consider engine bay space, accessories, clearance to firewall (I had to notch my valve cover to clear with a short deck), header availability/fitment for a tall deck but is an option. I thought about a tall deck to move up to a 632 but it introduces a lot of other issues.
05-24-2017, 06:44 PM
#12
The aluminum heads do more than just weight. They help cool the engine, they are much more forgiving on tuning than an iron head, and if the tune is missed and you torch an iron head it is junk. Aluminum you weld it back and mill it flat. I would HIGHLY recommend aluminum heads over iron.