Pictures from the shop a. old head b. working the head c. new valve seats with oversize intake valve d. new intake port (no more 'figure 8') e. finished head Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Depends how far you want to go obviously and widely variable, but with the new valves and some extras about $5K, or 100 quid at the current exchange rate Image Unavailable, Please Login
Fantastic! Ok Russ, put the plane on the side and lets get that Mondial back together. Spring is coming!
As most know, the stock exhaust valve proprtionately is too big to be optimal when compared to the stock intake. We chose to bring the intake flows up to meet a more ideal ratio. In addition to using a larger intake valve, the entire runner was ported, matched and tapered from the top of the intake manifold where it bolts to the larger 44 mm Weber DCNF carb (308 stock is 40mm). This allows more flow while increasing velocity of the charge, which improves drivability. The flow bench shows a 10%+ increase in max flow rates, the amount of time it is flowing at higher velocity is increased ("area under the curve" for flow rate x time) for (hopefully) more than a 10% volumetric flow. We decided NOT to go for max flow possible, as with my chosen carb set up the resulting low velocities the car would not be as low end friendly. The compromise was max flow at max velocity. In case some are wondering, we are shooting for a 36 or 38mm venturi (stock 308 is 32). The pictures show the qv carb manifold, the view from the carb mounting pad, and the manifold pad on the head. You can see the steady taper to promote charge velocity. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Wow, what a hog out! Did you have to do some welding to end up with such a large round bell shaped opening on the entrance of those heads?What is the diameter of the entrance of the port at the flange? What is the width 5mm in, 10mm in 15mms in, what is the width at the splitter and finally at the seat? Thanks a lot for sharing these pics.
And then it looks like a typical 330 or 365 port with 2 valves instead of one. How sad that our 308s were not ported and polished like every model before its production.If Nixon had not ruined the auto industry in the name of envoirmentalism we might have gotten Lucas timed injection and that means throttle response like F1.All The Cars are hand ported,but 308s got little in that way,breaking a long tradition for The Factory.The USA mandated CIS induction was from conception an air pollution device and even the euro Cars didnt escape the grasp of Congress.Thanks for the photos,those ports look vintage Modena to me.
More photos!! Here are some better photos of the intake ports and seats for the larger valves. Even though the intake valves are larger than a 348, the velocities are still higher than the stock 3.2. We will also be installing new guides and feathering them in. I've also enclosed a photo of the port matched intake manifold for the new 44 DCNFs, as well as a comparison shot between a 40 and 44 DCNF carb butterfly. (There is thread on the 40 to 44 DCNF swap). We had always heard a rule of thumb was to take out the "figure of 8" intake port shape and make it more like a 348, and that bears out in practice on the flow bench. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Here's another comparison - here is a photo of the "figure-8" intake port on the stock qv/3.2 head (reddish photo) and the more open 348-ish new ports Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
I would think the black coat on the cams is carbon residue from nitrogen hardening. I would polish the surfaces for the oil seals and clean the threads as well as the oil holes and then blow everything out with air. Regards Harry
