![]() While many people have found great increases with the Good Parts triple-carb setup, we stuck with just the cam and lifters.Īfter installing the cam and head, we moved to the ignition system and carbs. We turned to Good Parts for their $299 GP2 cam and $75 lifter set. Our test car’s camshaft was showing its age, so we decided to replace it. Since this is the most important part of a performance upgrade, we highly recommend seeking out a good shop for the work. We’ve seen a lot of “ported and polished” heads that were done by less experienced people as a result, we found they didn’t offer what they claimed. CD’s has an experienced staff that has ported a lot of cylinder heads through the years, so we knew we were in good hands. For about $800, they performed a three-angle valve job, opened the ports and shaved the face by 0.150 inch-that last move would raise the stock 7.5:1 compression ratio to 9.2:1. To get our project going, we pulled the cylinder head and sent it to CD’s Engine Service for some work. Likewise, a high-lift, long-duration camshaft won’t do much if the head can’t breathe well. Putting big carbs on a poorly flowing cylinder head is like increasing only the big end of a funnel if the small end is left alone, the funnel isn’t going to flow any better. While people are often quick to swap carbs and cams, the cylinder head is usually the key to any performance modifications. These can be rebuilt, but we had other plans. The stock engine setup included dual Zenith-Stromberg CD-175 carbs. Finally, we’d give the engine a good tune-up. To help get more air and fuel through that head, we’d also be adding a new camshaft, a pair of side-draft carburetors and a performance exhaust. The meat of our recipe would be a ported and shaved cylinder head. To that end, we decided on some mild changes that would give our TR6 the desired performance boost while maintaining its docile street manners. Additionally, we didn’t want to rebuild the engine or make overly expensive changes. Our goal was simple: We wanted to improve performance without sacrificing drivability. That horsepower number was also right where we expected it to be. The car covered the zero-to-60 sprint in about 13.5 seconds-disappointing, but what we expected-while its engine produced a maximum of 74 horsepower at the rear wheels. Before starting, we baselined its acceleration and horsepower figures. Our subject car is a very nice 1975 model that came to us with bone-stock running gear, including the engine, carbs and ignition. ![]() To return some street cred to the TR6, we set out to make some tried-and-true performance improvements on the car. While the TR6 is a beautiful car, it can’t get by on looks and iffy claims alone. However, even if we give Triumph the benefit of the doubt, those acceleration numbers are pretty lackluster in these days of 10-second minivans. These numbers have always seemed pretty ambitious to us, as 12 to 14 seconds seems normal for TR6s in the real world. At least, that’s what Triumph claimed early in the car’s production history. The TR6 can climb from zero to 60 mph in 10 seconds.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |