You Do The VoodooQI'm building a 400 small-block Chevy with flat-top Speed Pro pistons on 5.7-inch rods, 10.5:1 compression, and Vortec heads set up for 0.550 inch max lift that have been ported and polished. I'm topping off the engine with an Edelbrock Performer RPM intake and a Holley 750 carb. I would like to run a Lunati Voodoo cam with 233/241 degrees of duration at 0.050 inch of tappet lift, 0.504/0.525 inch max lift, but the flow tests I've seen done on Vortec heads seems to drop off at about 0.500 inch of lift. Would I benefit from running this big a cam? I'm only looking for around 400 horses. Keith FreemanVia e-mail
A I couldn't wait for someone to ask me what kind of cam I had in my engine. You'll be able to tell them it's total Voodoo! It varies its lift and duration based of the mood of the cam! You've got a killer package that you are building up here. Let's talk cam.
At first glance, I would recommend going with a smaller camshaft based on your horsepower goal. However, with the 10.5:1 compression with Iron Vortecs, I think that you're going to be knock-limited. The only thing that is going to let you get away with that kind of squeeze is the overlap of that big camshaft. It will bleed off cylinder pressure until you reach higher engine speeds, where the engine won't be so prone to knock. You're going to give up quite a bit of the slow-speed torque potential of the 400, but I'm sure that with your ported heads and the rest of your build that you should see somewhere around 450 hp.
Yes, the Vortecs do run out of air around 0.450 inch max lift and tip over at about 0.500 inch. If your heads were ported correctly, they should flow cleanly to 0.500 inch and slightly beyond. I wouldn't be concerned using the Voodoo (I just had to say it again) up to 0.525 inch of max lift.
Put this in something light and have a blast. It will sure turn some heads and the hamburger stand on Friday night.
Give Me A LiftQI'm getting ready to do an engine/ transmission swap on my '92 Chevy C1500 truck and I see a potential problem. I'm replacing the factory 4.3L V-6 and five-speed manual transmission with a mild 355 and TH400 trans. The factory speedo (which I would really like to keep) is an electronic type. The old TH400 is a geardriven cable style. What is the best solution for me to get correct speedo operation with these components? I found that in the early '90s Chevy did use a TH400 in many applications (a G30 van for example) that had electronic speedos. I found the GM part numbers for the vehicle speed sensor (PN 8655291) and rotor (PN 8655315) for these vehicles, only I'm just not sure if I can use them on my trans or not.Mark HussVia e-mail
A We checked with Tom Woodside at GMCOPO about your swap. Tom says you have the correct list of GM components to get the proper signal to the speedo. He reminded us that the speedo-driven gearhousing is in the transmission case, not the tailhousing. When you replace the speedo drive gear with the reluctor ring, PN 8655315, make sure you install it in the same axial location as the stock speedo drive gear you removed from the output shaft. Reinstall your tailhousing and bolt in the vehicle speed sensor in the standard speedo drive port in the trans case. This will give your speedo the signal it's looking for.