318 Four Barrel Intake
By Roy;
Just remembered::n my '81 Ram 360 I swapped out the original thermoquad and 4bbl intake for a stock 318 intake and 2bbl carb just to get better fuel mileage. Works great:::been on there for 17 years and guess what? "severe port mis-match" again.
Here Roy makes a claim. It is easy to believe. I know this will work. A poor running T-Q is a fuel burner and in a time past, rebuilding them wasn't easy, part wise. There easy carbs to rebuild.
Though the T-Q's primarys are smaller, the 360 is a larger engine and pulled air and fuel accordingly. Through the 318 2bbl and smaller runner intake. The air and fuel was going very fast for atomizing.
The port mismatch he talks about is one that leans to his bennifit. The intake port are smaller than the heads port window. No problems.
The problem (And not a big one) is when a larger window intake (340/360) is used on the smaller windowed head. ( 318 )
The air and fuel crash into the head and tumble into the port. Fuel can reform into droplets and not burn well.
Now yuo all must understand that even in the high speed of this happening, even the smallest things show up and will effect power, mileage and emissions. Sounds crazy, but look at what the auto manufactures are doing today. Big difference from years past.
By Roy again;
I sold my original Ram 4bbl intake/thermoquad to a co-worker with a '73 318 powered motorhome, he simply wanted more power. Again, port mis-match but he was thrilled with the power increase/ He would have spent far more money to get a "proper" intake to match his ports, and would have ended up with less power as well.
Here the engine is seeing a big increase in air and fuel delivery. This is why power jumped. A port matching intake would have made more power.
Price of the proper port sized power vs. cheap bolt on power? Your wallet may be the deciding factor. But you'll get it ethier way.
If you use the 360 sized intake, port match the 318 heads to the 340/360 head.
Who remembers Mr. Tony West's web page?
The kicker of the link is when he dyno'd the engine. You should read through it all so you know the whole deal of what was done and going on. At the end, here is further proof of what happens when parts are matched up. Now it's up to you or your wallet.
Click this!
http://www.geocities.com/alwest_83/318
(Performer intakes can be cheap at swap meets, but factory 4bbl's should be a fraction of the cost. Up-sizing the 318's port isn't going to kill the heads performance. If done right, it will still make more power than a stock port and valve sized 360 head. The important areas to match would be the roof and side walls, center divider on the inner pair.)