Chevy Car Questions & Answers - Performance Q & A

Kevin McClelland Oct 1, 2009 0 Comment(s)

Sprinting
Q: First, I've been a subscriber for about a year now, and, well, frankly, what a great mag. Last year I had a '77 GMC Sprint given to me-yes, given to me. It has 79,129 original miles and for the most part is in primo condition. It's bone stock, right down to two-barrel 305 under the hood. Where is a good place to find resto parts? I've scanned the 'Net. If it were a '72 or older I'd be set, but no one seems to stock items for '73-77. That's a real drag. I'm really looking for a new crossmember so I can make it a dual-exhaust when I swap in the engine I'm putting together. Any help you can give me sure would be great. Thanks.

Tim Huggins
South Paris, ME

A: Where do I get in line to have a car given to me, especially one that has 80,000 miles on the clock? Yes, the mid-'70s A-body GM cars were not very popular. They basically fell off the map in 1973, when the emissions regulations choked any performance they had right out of them. As for restoration parts availability, they are just about a popular as the cars were! I think we can help with the trans crossmember.

Check out G-Force trans crossmembers by Performance Transmissions and Parts. The dual-exhaust crossmember is fabricated from square-tubing steel with provisions for dual exhaust. This crossmember (PN 37XM-2) will fit all '73-77 A-bodies except for convertibles with boxed frames: four-speed manual, TH350, TH400, TH700R-4, and 4L60 transmissions.

Take care of that freebie ride.
Source: transmissioncenter.net


Chasing Your Tail, Part 2

Q: Regarding the "Chasing Your Tail" article in May '09, I just wanted to pass my experience on to Herb. I had the exact same problem he is describing with my GMC pickup. It ran fine under low loads, but once a load (trailer) was introduced the thing would start falling flat on its face. I went through all the painful troubleshooting (part swapping and tracing all of the grounds), and my problem ended up being a bad (weak) ignition coil. I would have sworn it was fuel-related by the way it was acting, but ultimately it was the coil. I figured it is cheap enough that he may want to try one.

Bill French
via email

A: Thanks for the tip. Yes, spark and fuel can be very difficult to pinpoint. Unless you can run a vehicle on an oscilloscope, it's hard to know if the coil is keeping up with the demand of the engine's cylinder pressure. Even then, unless you can run the engine under load and watch the secondary spark energy, you may not see the problem. The best is to have a scope when a vehicle is on a chassis dyno to apply load. It gets really tough running next to a truck with a scope on your back. Thanks again!

Eat My Words
Q: In the May issue you responded to a question about the LT/LS engines, stating that you would never consider the Gen III engines small-blocks. What is your reasoning on this? I have two old-school small-block Chevys (a '66 Chevelle with a 383, aluminum heads, a hydraulic roller, and a carb; and a '65 Corvair setup for Open Road Racing with a mid-mounted all-aluminum 400, a solid roller, and a carb). I also have a '04 Tahoe that came with the Gen III 5.3 engine, which I just replaced with an LQ9 6.0 using a LS6 cam. So I do have a little experience with both Gen I and III engines. The bore spacing is the same for both, at 4.400 inches, and the outside dimensions are pretty close. I know the Gen IIIs are better in every way than the Gen Is and have more room for a stroker crank. In fact, I guess GM is coming out with a 454 Gen III crate engine. However, in my mind, the Gen IIIs are still small-blocks. And World Products is introducing a new block that will use all the "old" small-block internals but will accept the Gen III heads and intakes. So if they aren't small-blocks, then what are they? I've had this conversation with a few other gearheads. What makes a small-block? Is it outside dimensions, cubic-inch possibility, or weight? I thought it was primarily the outside dimensions regardless of how many cubes it may have.

Charlie Friend
Alamogordo, NM

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