Needs More Oomph
I’ve been reading your column for some time now, and find that you always seem to give good, common sense advice to those of us with a limited car budget/limited expertise, so I’m hoping you can help me with my issue. A couple of years ago, I ordered and installed a factory 350 crate engine (385-horsepower 350 Fast Burn) into my ’70 Camaro. At the time, I thought 385 horses would be enough, but now I feel the need for more power. The engine has less than 20K miles and is linked to a TH350 transmission (with a shift kit) and the rear gears are stock (I think 3.08). The car is used for cruising to local car shows, but will occasionally see some red-light to-red light action.
I’ve asked local engine builders for advice and I’ve gotten a variety of answers, but there doesn’t seem to be much of a consensus. Budget is, as always, a concern and I don’t really want to go through the time and expense of building a new engine. What can you recommend that I do to increase the horsepower in my 350 Fast Burn? Any suggestions you can make would be greatly appreciated. Thanks.
In a nutshell, I’d recommend that you make it breathe a little better. I’d probably leave the basic short-block alone, and I wouldn’t really advise bumping the compression up either; you certainly don’t want to run into issues with being able to use readily available pump gas. If you maintained the original package (check out the specs here gmpartsdirect.com/results.cfm?partnumber=19201331) in its entirety, it already has a pretty decent cylinder head, which are topped with an aluminum dual-plane intake and a Holley 750. I’d recommend having a skilled and knowledgeable cylinder head guy do some massaging to help the flow characteristics of what you already have. This could be worth 40 horsepower or so. You can obviously upgrade the intake, but I’d consider just having the same guy spruce it up a little (i.e., matching the ports).
Additionally, step up the camshaft with the readily available and well-documented LT4 Hot Cam upgrade, along with a set of 1.6 roller rockers. The cam and rocker swap alone should take you to around 430 hp.
You don’t mention what your exhaust configuration is, but obviously a decent set of headers and free-flowing mufflers are requisite. You mention a 3.08 rear gear, and that’s a very likely choice whether it’s a 10-bolt or a 12-bolt. To determine what you in fact have, you can simply mark the driveshaft and count revolutions versus one full rotation of the rear tire. If it is a 3.08, you can help get things moving a little better with a set of 3.55s or 3.73s.
Stop The Squeal Deal
I recently installed a new Blueprint crate engine from Summit Racing. The engine is a 355 and the car is only street driven. Since day one I have been plagued by a squealing fan belt on the alternator. The fan belt will squeal at 3,000 rpm in every gear (Tremec TKO 500 five-speed). I have tried to tighten up the tension and the squeal will continue at a higher rpm, but I know that I am over tightening the belt. I am using a six-rib serpentine two-belt system with pulleys supplied by Vintage Air. I have also tried switching belts using Goodyear Gatorbacks, Gates, Napa Micro V, and Dayco, all with the same results. If I loosen the tension then the belt will squeal at an even lower rpm. If I use a spray belt dressing the noise will disappear for a short time, but eventually will return again. Any advice will be greatly appreciated.
West End, NC
It certainly seems as though you have covered the basics in your efforts to diagnose the issue. My experience would tell me that a squealing belt noise is produced by only a few sources: a bad pulley or bearing, improper tension, improper alignment, or a worn or contaminated belt. Ruling things out one by one, a bad pulley or bearing isn’t going to go away with belt dressing. Tension, well you’ve moved the tension all over and just moved the squeal in conjunction, so I’m thinking that’s out. Worn or contaminated belt, well, obviously you’ve tried myriad of belts, so that one is out. The way I see it, you’re only left with one viable alternative, and that’s improper alignment. Frankly, as this was a “new” setup, that would probably be the most feasible reason even if we didn’t have the other inputs. Break out the straightedge, my friend.
Helping to Pick a Gear
First time custom-build newbie here with the following specs:
• 1957 Chevy pickup
• Roadster Shop chassis
• Strange rearend
• LS3 with Imagine Injection, 603 hp/580 torque
• Hughes Performance 4L80E with a 2,800-3,000-stall converter
• Fast controller
• Black Widow 3-inch exhaust
My question is this; I want this to be a street truck with no track time at all, simply cruise-ins with the occasional stoplight drag race. What rear gear ratio should I run? My initial request to the builder was 3.89, but I am concerned about usability on the highway, engine noise, etc. I’m planning on using Pro Street Radial Hoosier tires, nice and fat. Any suggestions?
Congrats on the project, sounds like a bitchin ride. You have selected a great transmission for the build, basically all the strength of a TH400 but with the benefits of an 0.75 Overdrive, and the 2.48 First gear is nice, too. Additionally, the converter you describe isn’t so loose that you’re going see a great deal of added rpm due to slippage at highway speeds.
You don’t specify what size Hoosier Pro Street Radial you plan to use, so I’m guessing at your choice and picking either the 9.50R or the 10.50R. Here is a link to the Hoosier page in question regarding specific sizing information: hoosiertire.com/specstrt.htm. I’d be remiss if I didn’t advise you to consider Mickey Thompson tires as well. I’ve run their products on all my racecars for over 20 years, and you can check out their Street Radial page with the following link: mickeythompsontires.com/strip.php?item=ETStreetRadial. Also, Editor Campisano’s 509-powered Nova went 10.46/130 on Nitto 555 drag radials, then he and a buddy drove the car with the Nittos still on from Jersey to Tampa, so it’s a legit street tire with lots of bite.
For the purpose of this exercise and your application, I’m going to assume a 27-inch diameter. I might have shared this previously, but here is a link to a handy gear ratio calculator on Summit’s website, but it doesn’t offer an overdrive consideration: www.summitracing.com/expertadviceandnews/calcsandtools/gear-ratio-calculator. Here’s another one from a site by Accu Auto parts, and it has provisions for overdrive calculations: accuautoparts.com/calculator.php.
Running with the assumption of a 27-inch tall tire that’s rolling down the road at 65 mph with a 25 percent overdrive value, you’re looking at 2,360 rpm with the 3.89 rear gear that you’re considering. A 3.50 ratio would yield 2,123. So, when looking at the numbers, it’s obviously all up to you. Personally, I’d go with the 3.89 all day, but then again, you’re asking someone who commuted daily to college in a ’69 Camaro with 4.56s and no overdrive.
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