November 2012 Chevy High Performance Q&A

Power Tour Leaves

Kevin McClelland Sep 20, 2012 0 Comment(s)
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NOS slacker

I’ve been reading your magazine since I was a little motorhead. Your Q&A has been helpful throughout the years. My ’76 Camaro has a 383 pump-gas engine that runs in the 11.40s all day long. The car weighs 3,800 pounds with me in it. It has an Edelbrock Victor Jr. intake with a set of Canfield aluminum heads (215 cc). The cam is a solid roller with the duration at 0.050-inch tappet lift at 263/273, and is ground on a 110-lobe separation angle. The pistons are forged flat-tops; with the TH350 tranny with a 4:56 gear she goes through the lights at around 7,000 rpm with 29.5-inch tires.

I’m a foot braker and was thinking of going to a transbrake. I get 3,000-stall speed out of my 3,800 converter. Will a transbrake give me more stall speed off the line or just help with more consistent launches? Also, I hit it with a 150 shot of juice, but she only picks up two tenths at 11.17, is this normal? Any help will be greatly appreciated. Thanks and keep up with the great articles.

Tim Chitwood
Via email

I just have to ask, are you related to the famous daredevil Joie Chitwood? Chitwood’s team thrilled fans around the country for over 55 years with their last performance way back in 1998. Check out the videos on YouTube of their most impressive car control. OK, now that I got that out of my system, let’s see if we can help you find some e.t.

Let’s start with your 150hp nitrous shot—and we have to start with the basic questions: Do you have enough fuel delivery with the car already running 11.40s? You must maintain at least 5-6 psi of fuel pressure at the carb and nitrous fuel solenoid during the whole run. What are you running for ignition timing? We’re pretty sure since you are running on pump gas it’s in the low 30s. This should be fine, but if you are in the high 30s or anywhere close to 40, your engine is trying to kill itself when you add the nitrous. What is your bottle pressure when you are running? You need to have a bottle pressure of 950 psi. Most aftermarket nitrous systems tune their nitrous and fuel jet very conservatively. They usually expect the fuel pressure to be in the 4-5 pound range and the bottle pressure at 950 psi. This will make the system very rich if you’re running 6 to 6.5, which is normal. Also, if there is any restriction on the nitrous feed side, you’ll just be pumping in a ton of fuel without adding the appropriate amount of free oxygen riding along with the nitrogen. Most nitrous kits have a stainless steel filter screen on the AN fitting feeding the nitrous solenoid. The screen is on the pipe thread side of the fitting, so the only way to check this out is to remove the fitting from the solenoid. This screen gets plugged with crap from the assembly of the Teflon nitrous line that runs from the trunk, or from not taking care when changing bottles and getting dirt into the line and fitting. Check all these things, as we would expect at least a 0.5 reduction in e.t. if everything is working properly.

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