11-29-2002, 10:24 PM
|
 |
Senior Club Cobra Member
|
|
|
Join Date: Jul 2000
Location: Chilliwack,BC,
BC
Cobra Make, Engine: F5 Roadster
Posts: 1,422
|
|
Not Ranked
Rich,
The trick flow heads are mostly for racing. The AFR heads with 185 ports are a hot setup for a 5 liter and the new Roush 200 heads are good for 302's or 351's. I dyno'd my '87 5 liter mustang , it made more hp and torque with the stock cam and heads up to 3,800 rpm.Those big 305's will start haulin from 4,000 to 8,500 on a 347. Carbs work mostly on vaccuum/or lack of it under the carb and how much air[volume ] is going through it. With 305 intakes it is more like a big block chev head[[merlin heads are 320 intake cfm]They work good on 454's and 502's. The webers will have too much volume,not enough velocity, and the gas injested at LOWER rpm with the big ports the gas will 'fall' out of the air stream and puddle in the ports.This is more pronounced in a separate runner manifold like webers as the air will only be moving during the intake stroke with the intake valve open,say 90 degrees plus 60 more for overlap= 150 degrees,maybe more on a big cam. The rest of the time , 720 degrees minus the intake opening of 150 = 570 degrees of sequece ,the air will stop and large amounts of fuel will drop out of the air. The faster the rpm the better the flow of air and gas and it will overcome the puddling effect. So much for theory eh, webers/heads will made awesome power on the top end.
Perry. 
|
More cold weather inspiration!
Linear Mode
