Think ahead
So you’ve got the money saved to buy a new carburetor, and want to know which one. Well, it depends. Is this the last part you want to add? Or will it be a new camshaft next time? What you need to decide is what’s the end scenario. Will this be a carb and intake change only, or do you plan headers, camshaft, higher compression, nitrous also?
What’s ABSOLUTELY CRITICAL is to match the parts to each other and to the engine rpm. Let’s start with rpm, and here we’re talking big V8s. These perform very well in 2-6000 rpm band. You can buy a cam and an intake manifold and size the headers to give fantastic performance in the 4500-8000 rpm band, and some people do this. However there are 2 drawbacks. The first is that that car will be a pain to drive around town. Secondly, unless internal components like crank, rods, pistons etc. are changed the engine won’t survive very long at that rpm. In fact it’s likely you’ll have one smile-inducing run on the track, and then have to get someone to drag you home…
You should first decide which rpm band to be in, and unless you plan buy parts that will strengthen crank, rods, pistons etc. you should stay below 6500 rpm on V8.
Secondly buy all you parts to match that criteria. Companies like Edelbrock sells carb/intake manifold/camshaft packages that takes the guesswork out of it, and they work great. You don’t have to buy parts with the same brand name though, but if you do they probably match a little better. For some things it’s a definite advantage to stay with one brand. If you buy a MSD Ignition box and MSD distributor, the wiring will fit together. On the other hand it doesn’t matter if the plug wires are MSD or another brand.
Where do people often go wrong? Mae West said that too much of a good thing is wonderful. Clearly she didn’t tune her own cars… Because on parts selection too much is terrible. Most common errors are too big a carburetor and a camshaft with too many degrees. The too big carburetor makes tuning difficult and gives a sluggish car except above 5000 rpm. Too big a camshaft gives a lousy idle and no power below 4000 rpm. So drivability and economy will be terrible. The car will be powerful but only in the high rpms where the engine will not survive.
One comment on how a car feels… A car with too much carb and camshaft may feel very powerful the first time you try it, because the power comes in when you reach 4-5000 rpm. Suddenly you get a kick in the back. But that’s actually a bad sign, it means that the car has too little power below 4500 rpm. An engine is an airpump that based on parts choice has a certain max HP. As we’ve stated before, the best (=fastest and most fun to live with) car will have that power at all rpms. This car has lost that below 4500 rpm, and it does not have extra power above 4500 rpm, it just has what it should have had at all rpms.