Friends? Part Two
Q My name is Randy and I'm the other person referred to in the Performance Q&A question "Friends?" in the May '08 issue. Please let me straighten out the facts that my friend Larry twisted in his favor so you would agree with him. First fact: His car was never faster than my 406! Second, my trap rpm was 5,800 at 113 mph for a 12.168 e.t. with a 1.651 60-foot in a 3,530-pound Camaro (with me in it). My shift rpm was 6,000, and my engine has cast flat-top pistons from Midwest Motorsports, GM 5.7-inch rods, a stock 400 crank, and Aerohead 76cc GM 993 castings heads-and my Mickeys are 26x11.5x15, not 12.5s. Nothing high-tech here, the best parts are the Comp Cams Xtreme Energy cam with a max lift of 0.507/0.510 inch and the RPM Air-Gap intake. I just wanted the real facts to be known and I guess I'm stupid like that! The mathematical equation he referred to came out of Car Craft, using mph, tire size, and gear ratio to calculate rpm.
I have attached a copy of a time slip to prove my facts. See what this comes to now that you have the real numbers for my car. I've also included a picture of us at the starting line, and you can see the 3-inch exhaust doesn't hurt me. Ten feet out and I have him by a fender! I just can't believe he would stoop to fabricating numbers in his favor to try to prove his point. Thanks for clearing up the facts.
Wright City, MO
A Guys, you're killing me! It's either that the first liar doesn't have a chance, or with friends like these, who needs enemies. Write into a worldwide publication and slander your best friend? Tough stuff.
With the information you've given me (the truth?), you have about 300 rpm of converter slippage in the lights, which is about 5 percent. This is very common for the 3,000-stall converter your ex-friend Larry said you had. By my calculations, at 3,530 pounds and a 113.94-mph trap speed, your little 408 is kicking out around 470 hp. This is very respectable for a 406 with 993 iron heads. Looks to me like Larry has quite a bit of catching up to do. Also, he has quite a laundry list of far-from-stock parts pushing his Nova.
Sorry for any pain we may have imposed on you. I'm sure any pain you have felt from the previous column you can pass along to Larry with plenty of extra toppings. Good luck racing your Camaro. With your trap speed, high 11s are just around the corner. Keep refining your package and enjoy.
No Need For A Guide
Q In the Mar. '08 issue in the article called "Got Lobes?" you guys were talking about cams. There is a big gray box on the right side of page 28 and in reference to pushrods it says, "Do not use guideplates with self-aligning roller rockers." But it does not say why anywhere in the article. I am just wondering why. Does it have something to do with too much friction or what? It would seem to me like you can't be too accurate. I have self-aligning rollers on my 305 and I was about to buy guideplates until I noticed this in the article while I was rereading it the other night. Thanks for clearing this up.
A To cut costs and reduce the amount of parts in the engine, GM went to self-aligning rockers in the late '80s on the small-blocks. You'd think the more you could capture the valvetrain and keep everything in alignment the better it would be. Well, it just doesn't work that way. It's not because of the friction. It's more because of machining tolerances and the valve stem location in relationship to the rocker stud. When guiding the valvetrain, you want to use one or the other. You could easily put the pushrod in a bind if the valve stem and rocker stud aren't located perfectly. Also, you wouldn't want to run self-aligning rockers with cylinder heads that have the semicircle slot shape machined into the heads to guide the pushrod. I can guarantee these won't line up with the valve stem. Like I said above, choose one method of valvetrain alignment and stick with it.