![]() ![]() Please Log in or Create an account to join the conversation. You want something that looks like these (this is not a recomendation for the manufactuer or product, just an example of shape) Not sure if any of this helps with the original question, but thought I'd toss in my pennies (better than tossing my cookies, eh?). You want a large smooth flair, so the air can flow smoothly into the carb, if the edge of the mouth is too sharp you don't get a good boundry layer, the air will not flow as smoothly, and you get turbulence. The shape of the mouth of the velocity stack is verry verrrry important. My MGB uses a 1/4" plate with a radius to help smooth the air flow. You need to break that 90° edge where the air goes into the throat, it is possible to use a short stack (and they do have them, so short in fact they look like rounded rings). BUT, you don't necessarily have to have a long stack to get the benefits. Wiredgeorge is right, intake tuning is done by adjusting the length of the velocity stack, or intake runners (cars). more simple actually than the bike carbs, but all the principals apply. British cars use SU carbs (well some of them anyway), which are verrry similar to CV carbs. ![]() I'm no wizard, most of this comes from a book "Tuning BL's (British Leland) A-series engine" by David Vizard. I realize that the stack in a filter is a problem for bikes, just don't have much room. The best, if room is available, is to put a high flow air filter around the velocity stack, this will allow the air in, and allow the velocity stack to work it's magic. The problem with putting anything, including wire mesh to keep the birds out, in the mouth of the velocity stack is it will screw up the airflow, causing turbulence, thus loosing the benifits gained by using the stack. If this was allowed to happen, you could see the performance drop off as the valve job went away. The rider would put the towel in the front of his leathers, then make the pass, kill the motor, and make the turn off, stop get the towel out and wrap the carbs before being towed back the return road.Įven with the motor not running, there was a risk of the rear tire throwing dirt around and some could get in the carbs, only to be sucked thru the motor next time it was started. The seats and valve faces don't last long if you are sucking dirt in the motor.īack before pro stocks had air boxes, they would keep a towel wrapped around the carbs right up until the starter was plugged in. We can tell the heads that come into the shop that have been running no filters. It beats the stuff into the seat and valve face. The trash passing thru the intake port get hammered by the valve everytime it closes. Jay, why would not running filters hurt valve seats? Can you explain your comment? I can understand sucking in dirt/insects/tree branches might not due valve seats any good. Moved the topic to the carb forum where it seems to be more on topic. Our velocity stacks are designed for maximum flow and minimum height. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |