Competition Valve Job

Most people have read in their Car Craft and Hot Rod magazines that one of the first steps to improving the performance of their heads is to start with a 3 angle valve job. This statement is 100% correct, and it holds true whether your performing a backyard bowl blend, or porting a set of $ 15,000.00 Pro Stock heads. However, it does not tell the entire story. There are multitudes of different angles that can be put on a 3 angle cutter, and they most certainly do not all flow alike, and some flow way more than others. The hot ticket for one type of cylinder head might be totally wrong for another. The key lies in knowing what valve job to use for a certain application to make it perform its best. Unlike most shops who might have one type of 3 angle cutter ( I have seen plenty that didn't have any) that they put on everything, we have many different types of cutters. We have 3 angle, 4 angle, and 5 angle cutters that we use, along with several multi- angle cutters with a radius. Not only do we have, and use these different cutters, we have done exhaustive flow testing to find out which ones flow the best with each type of head, and know exactly which one to use to make your heads the best they can be.

While the above paragraph has focused on 3 angle valve jobs, there are many instances where a  4 or 5 angle cutter might be used, but bear in mind, just because one valve job has more angles than another, it doesn't make one better than the other. They each have their own application they are geared toward and work best on.

A set of heads does not have to be ported to respond to a competition style valve job, below is an example of a set of heads that we prepped for a competition engine that raced in a class that allowed no port work. We came up with the right valve job, and the proper valve prep that allowed these heads to shine over the typical bolt on set that most racers were using.

Valve Lift                    Stock                RGM Prepped

0.100                          43                          57                    Stock average  -  148 cfm

0.200                        104                        124                    RGM Prepped -   162 cfm

0.300                        150                        168

0.400                        184                        196

0.450                        191                        204

0.500                        200                        206

0.550                        201                        213

An average flow increase across the board was 14 cfm which usually will result in a 20-25 HP gain  .